Synopsis  

Endoscopic retrograde cholangiopancreatography (ERCP) was first described in 1968 and we have recently celebrated the 30th anniversary of endoscopic sphincterotomy. This diagnostic and therapeutic modality has impacted significantly in the management of patients with many different benign and malignant pancreatico-biliary problems. A successful ERCP requires the coordination and cooperation of a dedicated and committed team of endoscopists, nurses, and assistants, as well as an organized and functioning unit. It takes many years to learn, and repeated practice, in order to master the skill of ERCP and to do it safely. It is important to understand the indications, contraindications, limitations and complications of individual procedures when offering ERCP to our patients. Although successful ERCP has replaced surgery as a treatment option for some difficult pancreatico-biliary diseases, we have also seen problems and complications arising as a result of endoscopic treatment. Prospective collection of data and selected randomized controlled studies with long-term follow-up are necessary to evaluate the true value of this technology in the overall care of our patients.

 Introduction   

Imaging of the pancreatico-biliary system   

Methods for imaging the pancreatic and biliary ductal systems continue to evolve. Correct application of ERCP (and other procedures) requires an up-to-date knowledge of all of these modalities.

ERCP   

ERCP is a direct contrast study of the pancreatico-biliary system. It is useful in the diagnosis and treatment of diseases involving the pancreas and bile ducts such as stones, benign and malignant strictures and developmental anomalies.

It is superior to indirect cholangiography (oral or IV) especially in cases with obstructive jaundice which leads to raised intra-biliary pressure and impaired biliary excretion of contrast.

Moreover, intrahepatic bile duct pathologies can be demonstrated by ERCP using occlusion cholangiography. Pathology in the gallbladder and cystic duct abnormalities can also be visualized, although ERCP is not the best imaging study for gallbladder disease.

ERCP vs. PTC   

Comparative studies of direct cholangiography studies, i.e. ERCP and percutaneous transhepatic cholangiography (PTC), should take into consideration the individual patients and the expertise of the operator; however, ERCP is considered less invasive than PTC.

ERCP has the added advantages of allowing duodenoscopy and pancreatography, which are helpful in the diagnosis of ampullary pathology and pancreatic abnormalities. ERCP can be performed in the presence of ascites and/or malignancies involving the liver, contraindicating PTC. In addition, bile and pancreatic juice can be collected for cytological and microbiological examination during ERCP procedures.

MRCP   

The development and refinement of magnetic resonance cholangiopancreatography (MRCP) has produced excellent quality pictures of the anatomy of the pancreatico-biliary system. It is non-invasive and can give images comparable to ERCP when performed well. Limitations are few and the diagnostic value is high, and it may replace diagnostic ERCP, especially in the investigation of jaundice. MRCP however, lacks therapeutic potential.

EUS   

Endoscopic ultrasonography (EUS) allows good visualization of the distal common bile duct (CBD), with an excellent diagnostic accuracy for ductal stones. It provides superb views of the pancreas, and is useful in defining underlying pancreatic pathology. Fine-needle aspiration cytology further complements the diagnostic capability of EUS in pancreatico-biliary diseases.

 Section I: Preparation for ERCP   

Room set-up and floor plan (Figs 1, 2)   

Correct layout of the ERCP room is easier if it is located in a purpose-built endoscopy suite with in-house fluoroscopy facilities, rather than a shared facility in the radiology department. A purpose-built room with fluoroscopy offers the advantage of a better floor plan, organization, and ready access to stored accessories required for the procedures. Daily activities can be better organized and there is less hassle in moving equipment and endoscopists.

Space   

The ERCP room should be large enough to house the endoscopy equipment, monitors, and the fluoroscopy unit. There should be ample room for the endoscopists and nurse/assistant(s) to manipulate accessories. Additional space is required for trainees and interested observers. Space should be available for anesthestic support and resuscitation equipment when needed. Ideally, there should be no cables or tubing on the floor that may hinder movement of carts or trolleys. Accessories should be organized and stored to facilitate easy retrieval during procedures.

Position of monitors and endoscopy cart (Fig. 2)   

Some units have the endoscopy monitor mounted on the endoscopy cart at the head of the patient, which means the endoscopist has to turn to the right, away from the patient, in order to observe the endoscopy image. This bodily rotation tends to change the position and orientation of the scope and is best avoided. It is better to have the fluoroscopy and endoscopy monitors placed side by side facing the endoscopist, on the opposite side of the X-ray table (Fig. 3).

Because of the position of the fluoroscopy machine, the monitors may need to be placed at a 15–20° angle off to the right of the endoscopist for easy observation. The monitors are best ceiling mounted or supported on a stand placed at eye level. The endoscopist should adopt a comfortable position to avoid twisting and turning of the body, which may predispose to scope displacement or straining of the back and neck . The endoscopy tower is usually placed on the right behind the endoscopist, with sufficient room left in between for the manipulation of accessories.

Essential equipment for ERCP   

Side-viewing duodenoscopes   

Standard 3.2 mm and large 4.2 mm channel video endoscopes are now used routinely for diagnostic and therapeutic procedures. Smaller pediatric duodenoscopes (with a 2.0 mm channel) are available for examination in neonates. The standard adult duodenoscope can be used in children above the age of two. Older non-immersible scopes cannot be properly reprocessed and are therefore not recommended for ERCP because of the risk of cross-contamination. A jumbo-size duodenoscope (5.5 mm channel) can be used as part of the mother and baby scope system, but it is more difficult to manipulate.

Forward-viewing scopes   

Upper GI endoscopes may be used occasionally in patients with altered anatomy such as previous choledochoduodenostomy, Billroth II gastrectomy or in patients with hepaticojejunostomy to facilitate intubation of the afferent loop.

Medication   

A combination of sedatives and analgesics are used to provide conscious sedation during the ERCP procedure. Medications drawn up in syringes should be clearly labeled to avoid making mistakes during drug administration.

Sedatives and analgesics   

Standard medications used for IV conscious sedation include demerol (meperidine) or fentanyl, and valium (Diazemuls) or midazolam (Versed). The dose requirement is titrated according to the patient's response. For an average size adult, we usually start with 25–50 mg of merperidine or 25–50 µg of fentanyl, and 2.5–5 mg of valium or 1–2 mg of midazolam. Additional injections are given during the procedure as needed. IV benadryl 25–50 mg or IV phenergan may be given to enhance the sedative effects.

Anesthesia   

General anesthesia with IV propofol is used increasingly for complex ERCP procedures, especially in anxious patients, those who use chronic narcotics or excessive alcohol and others with a history of poor response to standard sedation.

Smooth muscle relaxants   

Glucagon (0.25–0.5 mg) or buscopan (20–40 mg) are given intravenously in increments to relax the duodenum and to facilitate cannulation.

Reversal agents   

Reversal agents including naloxone (Narcan 0.4 mg) and flumazenil (1 mg) should be readily available to reverse the effects of sedation.

Monitoring during conscious sedation   

A qualified nurse (or anesthetist) should be assigned to administer conscious sedation and to monitor the patient during the ERCP procedure. This nurse should have no other responsibilities. Medications are given in incremental doses based on the patient's response and condition in order to avoid oversedation. Vital signs including blood pressure, pulse, EKG, and oxygen saturation should be monitored continuously.

Supplemental oxygen can be given via a nasal cannula at a flow rate of 2 liters/min; this has been shown to prevent hypoxia. Care must be taken to avoid giving excess oxygen which may lead to respiratory depression in patients with COPD. Measuring the end-expiration CO₂ level using capnography is carried out in some centers.

Contrast agents   

The most commonly used contrast media such as conray 280, urografin, hypaque, and renografin contain iodine. Contrast media used for ERCP include both hyperosmolar ionic medium and isosmolar, non-ionic medium. Isosmolar non-ionic contrast agents are more expensive but should be used in patients allergic to iodine. In addition it is advisable to give these patients steroid prophylaxis and benadryl prior to the procedure to prevent contrast reaction.

Contrast should be drawn up in clearly labelled syringes prior to the procedure and be ready for use. It is preferable to have at least two 20 ml syringes filled with contrast of normal and half normal strength. A 20 ml syringe is used for contrast injection because it is easy to handle, contains sufficient volume of contrast, and permits injection by the endoscopist. Normal strength contrast should be used for initial cannulation for better visualization of the pancreatic duct. Half normal strength contrast is used to identify ductal stones in patients with dilated bile ducts.

Syringes for aspiration and irrigation   

An empty 20 ml syringe is used to aspirate bile for culture and cytology. Sterile water is used to flush the catheters prior to insertion of hydrophilic wires or exchanges.

Organization and storage of accessories (Fig. 4)   

There is a wide range of ERCP accessories. These include cannulas, sphincterotomes, guidewires, baskets, balloons, dilators, nasobiliary catheters, stents, biopsy forceps, injection needles, and more complex devices such as mechanical lithotriptors.

The accessories should be catagorized and organized, and stored to allow easy retrieval as well as stock-keeping. A limited supply of commonly used items should be clearly labeled and displayed on shelves like books in a library.

Similar items are best grouped together and more specialized items kept separately. A detailed catalogue list and location of all accessories should be kept for quick reference. It is helpful to establish a preprocedure 'game plan' so that the necessary accessories can be retrieved and readied for use.

Organization of the worktop (Fig. 5)   

To minimize cross-contamination of unopened accessories it is preferable to separate the clean and soiled items onto different worktops. Long accessories tend to uncoil and they are best organized with a clip.

A small pot of 30% alcohol is useful for cleaning the gloves (finger tips) to remove any sticky contrast or bile. Alcohol also reduces friction at the biopsy valve and facilitates insertion of accessories. Gauze pads are used for cleaning and wiping. Sterile water with simethicone can be flushed down the channel to suppress bubbling in the duodenum to improve visualization.

Fluoroscopy for ERCP   

ERCP is ideally performed with the help of a radiologist, but more commonly done with the help of a trained radiology technician. Endoscopists who personally operate the fluoroscopy unit during the procedure should receive basic fluoroscopy training and appropriate local licensing.

Fluoroscopy units (Fig. 6)   

Conventional X-ray machines as used for barium studies, are adequate for ERCP examinations. High-resolution digital fluoroscopy units produce better pictures but they are also much more expensive. A portable digital C-arm unit can be used but the resolution may be inferior to the full digital unit. It is preferable to use a machine with an under-couch X-ray tube. The X-ray machine should be capable of taking spot films. Digital units can store the images onto a computer for subsequent retrieval and review. Hard copies of selected images can be printed for reporting and filing. It is essential to know the magnification factor of the machine for correct interpretation of X-ray findings, and for measuring the size of stones and the length of strictures.

A high-resolution monitor is necessary as diagnostic interpretation and therapeutic procedures are often performed in real time under fluoroscopic guidance. The X-ray table should have an electrical remote control for fine adjustment in positioning and preferably be able to tilt in two directions. Apart from built-in shielding, additional pieces of lead can be placed over the side and head end of the table to protect staff from scattered radiation.

KV and mA   

These are the settings on the X-ray machine that determine the penetration of the X-ray beam and quality of the image generated. Most digital machines can automatically adjust the setting according to individual patients.

Split screen   

The area of interest seen on fluoroscopy can be reduced to allow fine focus on a smaller area. This gives greater detail and reduces the radiation exposure.

Magnified view   

A magnified view gives an enhanced image of the area of interest, but it also doubles the radiation exposure. It is sometimes necessary for proper localization of the tip of a guidewire or accessories during manipulation in the pancreas or for selective ductal cannulation.

Orientation of fluoroscopic images   

The orientation of the fluoroscopic image on the monitor varies depending on the individual endoscopist's personal preference. Some prefer to orientate the image in the conventional way of viewing X-ray films. Some, however, prefer to orientate the fluoroscopic image according to the anatomical position, i.e. right side of the screen corresponds to right side of the patient lying in a prone position (Fig. 7).

Personnel protection (Fig. 8)   

Individuals working with or around the fluoroscopy machine should be protected from scattered radiation by using standard lead aprons (lead thickness 0.2–0.5 mm). If a one-sided lead apron is used, it is important to keep the apron facing the fluoroscopy unit during screening. Individuals who need to turn around during fluoroscopy should have both front and back protection. To reduce the weight of the lead apron on the shoulder, a skirt and a vest can be used. A lead collar should be worn to protect the thyroid gland, and lead glasses are recommended, especially if a fluoroscopy unit with an over-couch tube is used. Individuals should also wear their X-ray badge on the outside for monitoring purposes. It is necessary to use external lead shielding of the reproductive organs for young or female patients.

Other protective gear   

Apart from radiation protection, standard staff should wear face shield or mask, impervious gowns, gloves, and shoe covers as appropriate.

Positioning of the patient   

ERCP is usually performed with the patient lying prone. It is important however to note that gravity will favor filling of specific parts of the pancreatico-biliary system with the patient in different positions. Turning the patient during ERCP examination may sometimes be necessary to eliminate overlapping shadows from superimposed bowel gas, bony structures, or the duodenoscope. This can also be achieved to some extent by rotation of a C-arm. Head up or down tilting the X-ray table helps gravity drainage to fill the intrahepatic system or the distal common duct.

At the end of the procedure, additional radiographs may be taken with the patient in a supine position. A change of position allows gravity to fill the more dependent portion of the right intrahepatic system and also the tail of the pancreas.

Positioning the patient in the right oblique position moves CBD off the spine and may reveal the cystic duct which sometimes overlaps with the CBD. This position may also allow a better examination of the gallbladder.

In rare circumstances, ERCP may be done with the patient in a supine position. The endoscopist will have to adjust the position by rotating more to the right, or even work facing away from the X-ray table.

Radiological interpretation   

Scout film (Fig. 7)   

A control film of the right upper abdomen should be taken with the scope in place prior to injection of contrast. With the patient lying prone and the scope in a short scope position, radiopacities or calcifications that lie above and to right of the scope represent calcifications either in the gallbladder, liver parenchyma, or proximal bile ducts. Calcifications to the bottom left of the scope generally represent pancreatic calcification or, rarely, stones in the distal CBD. The presence of air within the bile ducts maybe seen as an air cholangiogram and suggests a patent communication between the bile duct and the gut such as a patent stent, a fistula or a bilioenteric anastomosis.

Contrast studies   

Most diagnostic and therapeutic interventions are performed under fluoroscopic control; however, radiographs or stored images should be taken for documentation. Hard copy radiographs give better resolution compared to the fluoroscopic images and may reveal more detailed information.

If common duct stones are suspected early filling films should be taken during injection of contrast. This may demonstrate a "meniscus" sign where the stone is outlined by contrast within the duct. Excess contrast should be avoided as this tends to mask the small stones in a dilated duct.

With the patient lying prone the left hepatic system is more dependent and usually fills more quickly than the right side. If the cystic duct is patent, contrast may preferentially fill the gallbladder. The posterior segments of the right hepatic system are non-dependent in the prone position but may be filled more readily by turning the patient to a supine position.

Drainage films   

Delayed films after removing the duodenoscope are sometimes indicated if there is a clinical suspicion of a drainage problem, e.g. papillary dysfunction or stenosis. Drainage films may be taken with the patient in the right lateral position or in the Trendelenburg position.

The normal rate of drainage is affected by many factors and precise normal limits have not been established. Delayed drainage is however suspected if significant opacification of the bile duct persists after 45 min, and after 10 min for the pancreatic duct.

It is necessary to take hard copy spot films to document any therapeutic interventions. Alternatively serial digital images are stored and retrieved at the end of the procedure for reporting and filing.

The pancreatogram   

Normal anatomy   

The pancreas is a retroperitoneal organ lying across the abdomen at the level of L1 and L2. Pancreatic calcifications on the control film suggest chronic pancreatitis and rarely pancreatic neoplasm. A good quality pancreatogram should demonstrate the main pancreatic duct up to the tail with adequate filling of the second generation branch ducts. Excess contrast injection will result in acinarization or a parenchymogram.

The pancreatic duct normally has a smooth, slightly wavy course from the papilla tapering towards the tail. In the head a branch duct is seen draining the uncinate process. In addition the accessory duct (Santorini's duct) drains through the minor papilla.

In 5% of cases a prominent branch duct runs parallel to the main pancreatic duct giving the appearance of a bifid pancreas. Several branch ducts join the main pancreatic duct at irregular intervals, usually at right angles to the main duct. The branch ducts taper and themselves branch off into smaller ducts.

The diameter of the pancreatic duct varies according to the age and size of the patient. Elderly patients may have a slightly larger duct. The maximum diameter of a normal pancreatic duct is 6 mm in the head, 5 mm in the body, and 3 mm in the tail. Care must be taken to correct for magnification, which is usually 30%.

Pathological changes   

The pancreatic duct may appear normal in mild pancreatitis. In acute pancreatitis the pancreatic duct may appear slightly irregular with changes and irregularities of the side branches. Presence of a cyst or pseudocyst may cause complete obstruction of the pancreatic duct with or without communication with the duct.

The Cambridge Classification is used to document the severity of chronic pancreatitis (Fig. 9) as seen on a pancreatogram:

• Mild pancreatitis: a normal main pancreatic duct with three or more abnormal side branches.
  
• Moderate pancreatitis: an abnormal main duct with irregularities in three or more abnormal side branches.
  
• Severe pancreatitis: irregularity with strictures and dilation of the main duct, with filling defects suggestive of stones or filling of cavities or cysts.
  

There is no direct correlation between the radiological abnormalities and the functional loss in chronic pancreatitis because the pancreas has a good functional reserve. Leakage of contrast from a transected pancreatic duct with non-filling of the upstream duct is diagnostic of traumatic pancreatitis.

Cancer in the head of the pancreas may cause stricturing of the main pancreatic duct with uniform dilation of the side branches and the main duct upstream of the obstruction. In addition, the retropancreatic portion of the CBD may be involved, giving rise to the characteristic 'double duct stricture' sign. Displacement or stretching of the side branches may suggest an underlying tumor in the pancreas.

Congenital anomalies   

In patients with pancreas divisum, there is non-fusion of the dorsal and ventral ducts. The small isolated ventral pancreas drains through the main papilla. The dorsal (Santorini's) duct drains the bulk of the pancreas through the minor papilla.

The cholangiogram   

A good cholangiogram should visualize the entire intra- and extrahepatic bile ducts, the cystic duct and the gallbladder (when present).

Normal anatomy   

The upper limit of normal for diameter of the CBD varies somewhat with age but is approximately 7 mm (corrected for magnification). Contrary to common belief the bile duct does not dilate progressively as a result of cholecystectomy. Variations in ductal caliber can occur particularly in the retropancreatic portion and at the bifurcation.

Examples of normal anatomical variations include a long common channel seen in patients with congenital cystic dilation of the bile ducts, a low insertion of the cystic duct into the CBD and anomalous origins of the intrahepatic ducts.

In cases with biliary obstruction the level of obstruction may be defined by ERCP, with contrast filling the distal CBD. Filling of the proximal ducts depends on the tightness of the stricture but usually can be achieved by performing an occlusion cholangiogram. Contrast is injected under pressure by inflating a balloon below the obstruction to fill the more proximal obstructed system.

Pathological strictures   

Malignant CBD strictures appear as smooth or irregular narrowings with upstream dilatation (Fig. 10). These may be caused by cancers of the head of the pancreas (double duct stricture sign), gallbladder, or bile duct, or by lymphadenopathy at the liver hilum. Malignant bile duct strictures at the liver hilum are classified according to the Bismuth Classification:

• Type I stricture is confined to the common hepatic duct with >2 cm from the bifurcation.
  
• Type II stricture involves the common hepatic duct with <2 cm from the bifurcation.
  
• Type III strictures involve the right and left hepatic ducts.
  
• Type IIIa is involvement of the right side and IIIb is involvement of the left side.
  
• Type IV is multiple intrahepatic segmental involvement.
  

Malignant bile duct strictures can sometimes be difficult to distinguish from primary sclerosing cholangitis, which classically shows multiple strictures and diffuse irregularity of the extra- and intrahepatic biliary system.

In contrast, benign postsurgical strictures usually appear as a smooth short-segment stenoses. An air-filled periampullary diverticulum may compress the distal common duct giving rise to a pseudostricture formation. In these cases, the distal bile duct is seen to 'open up' when air is removed from the diverticulum.

Bile duct stones (Fig. 11)   

Stones within the bile duct may be demonstrated initially as a meniscus sign upon contrast injection and subsequently as filling defects. They are round or faceted depending upon their origin. It may be necessary to change the scope position into a long scope position to expose the mid-/distal CBD, an area otherwise overlapped by the scope. Rarely, parasites such as Clonorchis sinensis or Ascaris lumbricoides may be seen as unique filling defects in the extra- or intrahepatic bile ducts.

Gallbladder   

ERCP is not an ideal examination of the gallbladder. If the gallbladder is filled, a delayed film of the gallbladder should be taken after 30–45 min. This allows time for the contrast to mix with bile for better definition of gallstones (Fig. 12). Failure to fill the gallbladder despite adequate filling of the intrahepatic ducts suggests cystic duct obstruction. Stone impaction in the cystic duct may cause edema and compression of the common hepatic duct giving rise to Mirizzi's syndrome.

Underfilling and delayed drainage   

With an adequate intrahepatic cholangiogram underlying parenchymal liver diseases may be inferred from abnormal appearance of the intrahepatic ducts. Crowding of tortuous intrahepatic ducts may suggest liver cirrhosis. Stretching of a particular intrahepatic duct may be seen around space-occupying lesions such as abscesses, tumors, or cysts in the liver.

Underfilling of the bile ducts or 'streaming effect of contrast' may suggest an apparent narrowing in the distal bile duct. Inadequate filling due to stricture or obstruction may fail to detect intrahepatic pathologies such as stones in patients with hepatolithiasis. Functional obstruction at the papilla is difficult to diagnose, but is suspected if there is delayed drainage of contrast (>45 min).

The clinical diagnosis of papillary stenosis or sphincter of Oddi dysfunction depends on the presence of abnormal liver function tests with or without a dilated bile duct associated with right upper quadrant abdominal pain. Manometric studies are necessary to confirm the diagnosis in patients without obvious duct dilation or liver test abnormalities. Bile leaks and fistulas complicating biliary tract surgery can be readily identified on cholangiography.

 Section II: Diagnostic and therapeutic ERCP   

Diagnostic ERCP   

Scopes   

ERCP is performed using side-viewing duodenoscopes with a 2.8, 3.2, or 4.2 mm channel. All of these scopes readily accept a 5 Fr or 6 Fr catheter and accessories. The larger-channel duodenoscopes accept accessories up to 10–11.5 Fr diameter and are used for both diagnostic and therapeutic purposes. The larger instrument channel allows aspiration of duodenal contents even with an accessory in place, and also permits the manipulation of two guidewires or accessories simultaneously.

Accessories (Fig. 13)   

The cannula or diagnostic catheter is a 6 or 7 Fr Teflon tube which tapers to a 3–5 Fr tip. It is used for injection of contrast into the ductal systems. A variety of cannulas are available with different tip designs. A commonly used example is the bullet tip or fluorotip catheter, which has a small metal or radiopaque tip at the end to facilitate orientation and cannulation on fluoroscopy. Other catheters may have a tapered tip which facilitates cannulation. Some catheters have two lumens, which allow both injection of contrast and manipulation of a guidewire. Most allow the passage of standard (0.035 inch) guidewires.

Preparation of patient   

Most ERCP exams are performed on an outpatient basis provided that the patient is physically fit and recovery facilities are available. Rarely, ERCP is performed as an inpatient procedure for patients with significant comorbidities or those in whom therapeutic procedures or surgery may be necessary.

Informed consent   

ERCP is a complex procedure with significant potential hazards. It is important that the patient understands the potential benefits, risks, limitations and alternatives. Written, informed consent should be obtained in the presence of a witness.

Fasting   

The patient is instructed to fast overnight, or for at least for 4 h prior to the procedure. Outpatient procedures are preferably done in the morning to allow more time for recovery.

Antibiotics   

Antibiotics are given for endocarditis prophylaxis according to local and national guidelines. ERCP can cause clinical infection if the procedure does not relieve the obstruction and if cleaning and disinfection regimens are not ideal. Antibiotics are given prophylactically when difficulty in drainage is anticipated, e.g. in patients with multiple strictures (hilar tumors or sclerosing cholangitis), or pseudocysts. Antibiotics should also be given immediately if obstruction is not relieved.

ERCP procedure   

Intubation and examination of the stomach   

When the patient is adequately sedated a self-retaining mouth guard is placed and the patient is supported in a left lateral/semiprone position. This position facilitates intubation and examination of the upper GI tract with the side-viewing duodenoscope.

With the patient in the prone position, slight left rotation of the scope is required to correct for the change in axis. Gentle downward tip angulation allows examination of the distal esophagus. Once in the stomach, the gastric juice is removed by suction to minimize the risk of aspiration. The stomach is inflated slightly to allow an adequate view of the lumen.

The endoscope is slowly advanced with the tip angled downward looking at the greater curve and distal stomach. With further advancement, the scope will pass the angular incisura. The cardia can be examined by up-angulation and withdrawal of the scope.

Once past the angular incisura the tip of the scope is further angled downwards and the pylorus is visualized. The scope is positioned so that the pylorus lies in the center of the field. The tip of the endoscope is then returned to the neutral position as the pylorus disappears from the endoscopic view, the so-called 'sun-setting sign'.

Gentle pushing will advance the scope into the first part of the duodenum. The scope is angled downwards again and air is insufflated to distend the duodenum. Care must be taken to avoid over inflating the duodenum as this causes patient discomfort and makes the procedure more difficult. Careful examination is performed to rule out any pathologies such as ulcers or duodenitis. The scope is pushed further to the junction of the first and second part of the duodenum.

At this point, the scope is angled to the right and upwards, and by rotating the scope to the right and withdrawing slowly, the tip of the scope is advanced into the second part of the duodenum. This paradoxical movement shortens the scope using the pylorus as a pivot, bringing it into the classical 'short scope position'. The markings on the duodenoscope should indicate 60–65 cm at the incisors.

With the patient prone, and the scope returned to a neutral position, the papilla can be easily visualized, in the middle of the second portion of the duodenum. The landmark for identification of the papilla is the junction where the horizontal folds meet the vertical fold. Duodenal diverticula may cause difficulties with cannulation as the papilla may be located on the edge or rarely inside a diverticulum.

Approaching the main papilla   

A control film of the right upper abdomen is taken to look for calcification and for air in the biliary system, prior to injection of contrast.

Cannulation is performed in the short scope position allowing better control over angulations and tip deflection. In some difficult cases or in attempted minor papilla cannulation, the long scope approach may be adopted. Excess bubbles in the duodenum can be removed by injecting a diluted simethicone solution down the channel. Duodenal contractions may be reduced with the use of antispasmodic medication.

The presence of a periampullary diverticulum does not normally increase the technical difficulty of cannulation, unless the papilla is displaced or located inside the diverticulum (Fig. 14).

The normal papilla appears as a pinkish protruding structure and the size may vary. Abnormalities result from previous stone passage, stone impaction, or tumor.

Cannulation of the papilla   

Cannulation is best performed in an "en face" position. The cannula should be flushed and primed with contrast to remove any air bubbles prior to insertion into the duodenoscope. Air injected into the biliary system could mimic stones. Flushing excess contrast in the duodenum should be avoided since hypertonic contrast stimulates duodenal peristalsis.

A combination of twelve different maneuvres can be used for positioning the tip of the cannula for cannulation. These include up/down and sideways angulation, rotation of the endoscope, use of the elevator, and pushing in and pulling back of the scope. Suction collapses the duodenum and pulls the papilla closer to the endoscope. Air insufflation pushes it away. Most beginners find pancreatography easier to obtain than cholangiography. The pancreatic duct is normally entered by inserting the cannula in a direction perpendicular to the duodenal wall, in the 1–2 o'clock orientation (Fig. 15).

Fine adjustments of the position and axis of the cannula are helpful. Excessive pressure in the papilla is best avoided because pushing may distort the papilla and increase the difficulty with cannulation. Cannulation of the CBD is usually achieved by approaching the papilla from below, in line with the axis of the CBD. It may be helpful to lift the roof of the papilla, and to direct the cannula towards 11 o'clock (Fig. 16).

Full strength contrast should be used initially, and is injected under fluoroscopic control. The pancreatic duct should be filled until the tail and some side branches are visualized. Avoid overfilling and acinarization as this increases the risk of post-ERCP pancreatitis. When filling the CBD, start with full strength contrast and consider switching over to dilute contrast when stones are visualized. If deep cannulation is successful aspirate bile before injecting contrast to avoid excess excess contrast masking small stones in a dilated biliary system.

The left hepatic ducts usually fill before the right because they are dependent with the patient lying prone. The gallbladder is usually filled except in cases with cystic duct obstruction. Multiple spot films are taken during contrast injection. It may be necessary to change the scope position to expose the portion of the common duct hidden behind the scope.

At the end of the procedure the endoscope is withdrawn and air suctioned from the stomach to minimize discomfort. The patient is then turned to a supine position and more radiographs taken in different projections (as previously described).

In patients with a partially filled gallbladder immediate diagnosis of gallstones may be difficult due to inadequate mixing of contrast with bile. Delayed films of the gallbladder (after about 45 min) may reveal small stones after allowing time for the contrast to mix with bile.

Ease and success in cannulation   

Success of diagnostic ERCP depends on the experience of the endoscopist and the presence or absence of pathology. Successful cannulation of both ductal systems is commonly achieved in 85–90% of cases with experts achieving rates of over 95%. The success rate is lower in patients with previous gastric surgery, e.g. Billroth II gastrectomy.

Minor papilla cannulation   

The minor papilla is located proximally and to the right of the main papilla. It can be identified as a small protruding structure. It may not be obvious or may appear as a slightly pinkish nipple between the duodenal folds. When prominent, it can sometimes be mistaken for the main papilla, however, it does not have a distinct longitudinal fold and the small opening usually resists cannulation.

Cannulation of the minor papilla is indicated in patients with suspected or proven pancreas divisum and when cannulation of the pancreatic duct fails at the main papilla. Cannulation of the minor papilla is usually best done in a long scope position using a 3 mm fine metal tip cannula. Bending the tip of the cannula to form an angle facilitates cannulation.

It is important to identify the correct location of the orifice before any attempt is made to inject contrast, as trauma from the cannula may result in edema and bleeding and obscure the opening.

If the papilla or orifice is not obvious, it is useful to give secretin by slow IV infusion and wait 2 minutes to observe the flow of pancreatic juice. During injection, it is important to monitor the contrast filling by fluoroscopy as the tip of the cannula is often hidden by the endoscope in the long scope position.

Complications of diagnostic ERCP   

The complication rate for diagnostic ERCP is very low in experienced hands. In addition to the specific risks related to ERCP, the procedure also carries the risk of any endoscopic procedure including those related to sedation and scope perforation.

Respiratory depression and other complications   

Adverse drug reactions and respiratory depression due to excess medication may occur. . This complication is best prevented by giving sedation slowly in small increments, and by assessing the overall response of the patient. Proper monitoring of blood pressure, pulse, and oxygenation helps to avoid this complication. The use of oxygen at 2 liters/minute given via a nasal catheter helps to prevent hypoxia. Glucagon may increase the blood sugar level in diabetic patients and the anticholinergic effect of buscopan may cause tachyarrhythmia. These unwanted side-effects should be monitored.

Pancreatitis   

Pancreatitis is the commonest serious complication of ERCP. The serum amylase often increases transiently following pancreatography and may be of little clinical significance. The incidence of clinical pancreatitis is 0.7–7%. The risk is higher when the pancreas is overfilled, in patients with sphincter of Oddi dysfunction with manometry and in those with pancreatic manipulation.

Cholangitis   

The risk of cholangitis after ERCP is uncommon but may increase in patients with bile duct obstruction due to stones or stricture, especially when biliary drainage cannot be established. The risk of sepsis is high in patients with acute cholangitis when the intraductal pressure is raised by excess injection of contrast. The risk can be reduced by aspirating bile before injecting contrast.

The most common bacteria causing biliary sepsis include Gram-negative bacteria, i.e. E. coli, Klebsiella, and Enterobacter, and Gram-positive Enterococci. An improperly reprocessed duodenoscope may carry a risk of cross-infection with other bacteria such as Pseudomonas spp.

Failed cannulation and special situations   

What to do with a difficult intubation   

Failure to insert the duodenoscope   

Side-viewing scopes are usually easier to pass into the esophagus than standard forward-viewing scopes because of the rounded tip. Difficulty may be encountered if the patient is anxious or struggling due to inadequate sedation. Careful explanation and reassurance prior to the procedure helps to alleviate the patient's anxiety.

It is sometimes difficult for patients to swallow in the prone position. Supporting the patient in the left lateral position during scope insertion may help to overcome this problem. Check that the scope angulations are appropriate and advance the tip of the scope over the tongue and against the posterior pharyngeal wall, scope insertion is facilitated by asking the patient to swallow.

Do not push if resistance is encountered. It is important to synchronize your push with the patient's swallow. If in doubt, rule out any obstructing factors with a forward-viewing endoscope. In rare cases, it may be necessary to guide the scope with the left index finger in the oropharynx.

Lost in the stomach   

Negotiating the stomach with a side-viewing duodenoscope is sometimes confusing. A side-viewing endoscope can function like a forward-viewing endoscope if the tip is deflected downwards. Orientation is easier if the patient is in the left lateral (rather than the prone) position.

Rotation of the patient into the prone position changes the axis of the stomach, and the tip of the scope often ends up in the fundus. Air is insufflated to distend the stomach until an adequate view of the lumen is obtained and to locate the greater and lesser curves.

Downward angulation facilitates examination of the lumen and further passage of the endoscope. If the tip of the scope catches against the mucosa, upward angulations will lift the tip away. It may be necessary to rotate the scope gently to the right to align it with the axis of the stomach.

Passage of the scope is made by a series of up and down tip deflections and pushing movement. Advance the tip until the distal antrum and pyloric opening is seen.

Position the pyloric opening in the center of the endoscopic view then return the tip of the scope to the neutral position and gently push the scope through into the duodenum. It is important to note any changes in the orientation of the pyloric opening while changing the tip position since sideway angulations/rotation may be necessary to compensate for a change in axis.

In a J-shaped stomach secondary to deformity, it may be necessary to deflate the stomach and even to apply abdominal pressure to assist scope passage. If the pyloric opening is tight or deformed, backing the tip of the scope by downward tip deflection or, rarely sideway angulations may help to 'drive' the scope into the duodenum. Again, intubation of the pylorus is much easier in the left lateral position.

Insufflate small amount of air to distend the duodenum to identify the junction of the first and second part before advancing the endoscope. Passage through a tortuous or deformed duodenum may again require downward tip deflection and checking the axis or orientation before upward tip deflection while pushing to advance the scope.

Once the tip of the scope has passed the D1/D2 junction, return the scope to a 'short scope' position by up and right angulations of the tip and rotation to the right, while pulling back the scope gently. The patient should now be placed to lie in a prone position. The papilla is normally seen when the scope is returned to the neutral position after this shortening maneuver, with the markings of 65–70 cm at the incisor level in the majority of patients. If examination of the stomach is performed with the patient in a prone position, initial rotation of the scope to the left will compensate for a change in the axis and makes the examination easier.

Failure to identify the papilla   

Tip of endoscope is too proximal   

The tip of the scope falls short of the second part of the duodenum. This failure to shorten into a 'short scope' position is usually due to duodenal deformity caused by existing ulceration or scarring, previous ulcer surgery or nearby tumor. The malpositioning of the scope is obvious on fluoroscopy. Advance the scope further by pushing gently with downwards and sideways angulations to negotiate the bends into the third portion of the duodenum before withdrawing the endoscope.

Rotation to the right may be necessary to maintain the scope position and prevent it from slipping back into the stomach. Sometimes cannulation has to be performed in a distorted and long scope position because of duodenal deformity. Care should be taken while pushing the scope through a stenosed duodenum (especially in cases with tumor infiltration) to avoid a perforation.

Tip of scope is too distal   

The tip of the scope is inserted into the third part of the duodenum. This is sometimes encountered in a very short patient or as a result of over-energetic pushing of the endoscope. Fluoroscopy is useful for checking the position of the scope. In this situation relax the angulations and withdraw the scope slowly back into the second part of the duodenum, looking for the landmarks of the papilla. In a short patient (or child), the marking on the scope may read 50 or 55 cm and the scope may appear very straight on fluoroscopy. It may be necessary to push in and angle the tip of the scope upwards to gain a better position for cannulation.

Obscured papilla   

The papilla usually appears as a prominent structure normally located at the junction where the longitudinal mucosal fold meets the horizontal folds in the second part of the duodenum. In rare cases the papilla may appear as a flat and inconspicuous pinkish area. Excess fluid or bubbles in the duodenum sometimes obscure the papilla. Examination can be improved by squirting anti-foam agents such as simethicone solution and aspiration. The papilla may be obscured by an overhanging duodenal fold. Using the cannula to lift up or push away the covering mucosal fold will expose the papilla.

If the papilla cannot be identified, it is useful to look for the presence of a duodenal diverticulum in the second part of the duodenum. The papilla may lie on the edge, or sometimes within it. Pushing on the edge of the diverticulum may move the papilla into a more favorable position for cannulation. Excess air in the duodenum may distend the diverticulum, thus pulling the papilla away. Deflating the duodenum by suction helps to bring the papilla back into the duodenal lumen or into a better axis for cannulation.

In patients with previous sphincter surgery or sphincterotomy the biliary orifice is usually separate from the pancreatic orifice, and is found in a more cephalad position. A suprapapillary fistula may drain the bile duct and cannulation may fail at the main orifice. It is important to check for a fistulous orifice which may be hidden by duodenal folds.

What to do if cannulation is difficult   

Abnormal papilla   

Cannulation may be difficult in pathological situations such as an ampullary tumor or when severe acute pancreatitis results in local edema. Cannulation is still possible if the orifice is seen. For an ampullary tumor the orifice may not be obvious if the tumor replaces the whole papilla. It is important to avoid trauma to the tumor with the cannula since this often precipitates bleeding which makes cannulation more difficult if not impossible. It is worth spending a moment to observe the papilla and to identify the likely opening before attempting cannulation. The orifice may be located in the distal or inferior aspect of the papilla. Sometimes bile seen draining from the papillary orifice helps with localization. Blindly probing the papilla may create a false passage or result in intratumor injection of contrast or even a perforation.

Failed common duct cannulation   

This may result from failure to identify the papilla or a failure to inject contrast due to poor positioning (access) or orientation (axis). Cannulation is best performed in a short scope position, which allows better control over the tip of the duodenoscope. Avoid excess body or left wrist movement since these may affect the scope position. It is useful to insert the cannula and be ready for cannulation before performing fine adjustment of the scope position. Locking the wheel that controls sideway angulations helps to minimize movement.

Cannulation is best performed with the papilla positioned in the center of the endoscopy field. Proper alignment is achieved by a combination of up/down and left/right angulations rotation of the tip of the scope and pulling back or pushing the tip of the scope further into the duodenum. Suction to collapse the duodenum may pull the papilla closer to the scope. These movements, together with lifting the cannula using the elevator will help to align the papilla for cannulation.

If the cannula is seen to approach the papilla from the side, adjust the right or left angulation to put the papilla back into a central position. If the pancreatic duct is repeatedly cannulated the tip of the cannula should be directed upwards towards the 11–12 o'clock position by advancing the scope further into the second part of the duodenum, so that the tip of the cannula approaches the papilla from below and using the elevator to direct the cannula upwards in the axis of the CBD. Use the cannula to lift the roof of the papilla before attempting further insertion.

Putting a curl on the tip of the cannula may facilitate cannulation. In addition looping the cannula gently in the duodenum may help to align its tip with the axis of the CBD. Too much pressure on the cannula may impact the tip amongst the folds in the papilla and impedes the flow of contrast. Forceful injection of contrast may result in a submucosal injection.

A metal tip cannula (bullet tip) is sometimes better than a standard Teflon cannula. The smooth radiopaque metal tip facilitates cannulation under fluoroscopy. Injection of a small amount of contrast during attempted cannulation to outline either ductal system will help in correct orientation or alignment. If cannulation from below proves difficult because the cannula keeps sliding over the surface of the papilla it is useful to first angle the tip of the scope up close to the papilla and impact the tip of the cannula against the roof of the papilla before pushing the scope to change its axis. This so called 'kissing technique' serves to align the cannula in the orifice of the bile duct before repositioning in order to achieve deep cannulation.

If cannulation is still unsuccessful, a bowed double or triple lumen sphincterotome offers additional upward lift for cannulation of the CBD. Most endoscopists bow the sphincterotome in the duodenum before attempting cannulation. In this way, there is less control over the tip and cannulation is similar to fishing for the papilla with a 'hook'. It may be preferable to use the tip of the sphincterotome initially like a standard cannula for cannulation. When a change in axis is desired the wire is then tightened (this is difficult if the wire is still within the channel), lifting the tip of the sphincterotome in the axis of the bile duct. In addition, the sphincterotome is gently pushed out while advancing the tip of the scope further down into the second part of the duodenum. Sometimes sideway angulation is necessary to achieve a correct alignment with the axis of the bile duct. Frequent injection of small amounts of contrast during manipulation helps to guide the sphincterotome.

When conventional methods of deep cannulation fail a guide wire can be used to cannulate the bile duct. It is helpful to have contrast present in the pancreatic duct to guide the direction of the guide wire. We prefer to use a 0.025 or 0.035 inch hydrophilic-coated guidewire (e.g. Metro tracer wire from Wilson Cook). The flexible tip guidewire is inserted through a catheter or a sphincterotome and 5 mm of the tip is pushed gently in the direction of the CBD. It is important that the endoscopist or an experienced assistant perform the initial gentle probing (or exploration) at the papillary orifice with the guidewire as the feel and control of the catheter/guidewire is important.

When the tip of the guidewire is advanced without any resistance the catheter is passed over the guidewire into the ductal system. Passage of the guidewire into the pancreatic duct can be easily identified on fluoroscopy. When the guidewire and catheter (or sphincterotome) is inserted into the bile duct, the wire is then removed and bile aspirated back into the catheter to confirm the position before contrast is injected to outline the biliary system. The use of tapered tip cannulas and precut sphincterotomy increase the risk of submucosal injection and perforation, especially when performed by inexperienced endoscopists.

With a displaced papilla, it may sometimes be difficult to get into a correct axis with the papilla close to the endoscope. A cannula or sphincterotome can be positioned in the correct axis for cannulation even when the tip of the scope is further away from the papilla in a 'long' position. With a bulging papilla due to edema or an impacted stone the orifice of the papilla may be pointing downwards. It is helpful to advance the tip of the scope further into the duodenum and to approach the papilla from below in a long scope position. Using a bowed sphincterotome passed distal to the papilla and hooking the tip into the orifice is another way to achieve cannulation. Suction to decompress the duodenum may also pull the papilla closer to the endoscope.

Failed pancreatic duct cannulation   

The most common cause is an improper axis. The pancreatic duct is best entered by directing the cannula perpendicular to the duodenal wall in the one o'clock position. It is sometimes necessary to withdraw the tip of the scope relaxing the upward angulation together with adjustment of the sideway angulation and lowering the elevator to drop the cannula. Taking a radiograph in cases with an apparent failed cannulation may sometimes reveal a small ventral pancreas.

Pancreas divisum may account for non-visualization of the body and tail of the pancreas which can only be demonstrated by injecting contrast through the minor papilla. Obstruction due to carcinoma of the head of the pancreas may be misinterpreted as a ventral pancreas. Pancreatic stones may obstruct the pancreatic duct and prevent proper filling. Pancreatic cannulation may be facilitated by using a flexible tip guidewire.

Pancreatic duct cannulation may fail in cases with pancreas divisum since there may be no ventral duct.

Failed accessory (minor) papilla cannulation   

Identification of the accessory or minor papilla can sometimes be difficult. The minor papilla is located in the second part of the duodenum, to the right and proximal to the main papilla. It may be prominent in cases with obstruction of the main pancreatic orifice or with underlying pancreatitis. Cannulation of the minor papilla is necessary in patients with suspected pancreas divisum to outline the dorsal pancreatic duct. Cannulation is best performed in a long scope position and with the scope tip angled slightly to the right. This maneuver will put the accessory papilla in the center of the endoscopy field. In most cases, the minor papilla is not obvious and cannulation is difficult.

It is useful to give secretin by slow IV infusion and wait 2 minutes to observe for flow of pancreatic juice from the minor papilla. Once the papilla is identified cannulation is attempted with a fine metal (3 mm) or needle tip cannula. Bending the tip facilitates cannulation. It is important to avoid traumatizing the mucosa with the tip of the cannula, as bleeding may obscure the orifice. In the long scope position, the tip of the cannula may be hidden behind the endoscope on fluoroscopy but contrast is seen flowing across the spine when the dorsal duct is filled.

In difficult cases cannulation can be attempted using an 0.018 flexible tip guidewire contained in a fine tip Teflon cannula, using the tip of the guidewire to explore the orifice. Once the guidewire is inserted into the dorsal pancreatic duct the cannula is advanced over the guidewire and contrast is injected through the cannula after removal of the guidewire.

It is worth remembering that cannulation of the main pancreatic duct via the main papilla may fail even in patients without pancreas divisum. If no obvious flow of pancreatic juice is observed at the minor papilla after injection of secretin it is wise to re-examine the main papilla. A good flow of pancreatic juice at the main papilla suggests that the patient does not have pancreas divisum and further cannulation attempts should be made at the main papilla.

Failure to obtain get deep CBD cannulation   

This usually results from a failure to align with the correct axis of the bile duct. Pushing the tip of the cannula may distort the papilla. The scope is adjusted so that the papilla is in the central position. If the cannula is seen coming from below pointing towards the right or the anterior wall of the CBD, withdraw the cannula and relax the upward angulation of the scope. The direction or axis of the cannula can be altered by pulling back the scope until the curve of the cannula is in line with the axis of the CBD. Slight left angulation of the tip of the scope may help to slide the tip of the cannula into the CBD.

Manipulation is best performed with intermittent injection of contrast to outline the direction/axis of the CBD on fluoroscopy. Using a cannula with a metal or radiopaque tip will help in correct positioning. Care is taken to avoid repeated injection or overfilling of the pancreatic duct. If the bile duct axis cannot be defined, it may be necessary to use a sphincterotome as previously described.

If the bile duct is defined a guidewire can be used to facilitate deep cannulation. The guidewire is inserted initially into the bile duct and the cannula or sphincterotome is advanced over the guidewire. The guidewire is then removed and bile aspirated back into the syringe before contrast is injected to fill the bile duct. Sometimes, stone impaction at the papilla or tumor involvement may prevent deep cannulation of the CBD. A stiffer instrument such as a sphincterotome can be used to dislodge the impacted stone.

Precut sphincterotomy to assist in CBD cannulation   

Precut sphincterotomy can facilitate deep cannulation of the bile duct, and is used when standard cannulation fails in the presence of known bile duct pathology (e.g. impacted stone or tumor). Since precutting carries significant hazards, and other safer techniques are available, it should be used only with great caution. There should be a specific indication and a strong need to gain access into the bile duct, such as palliation of malignant jaundice. Precut sphincterotomy should not be done for a diagnostic ERCP or as an alternative to good biliary cannulation technique.

Needle-knife precut technique   

Precutting with the needle-knife is performed in two ways either by inserting the knife into the papilla and gently moving upwards, or by incising downwards from above the papilla. Prior insertion of a stent into the pancreatic duct protects the pancreatic orifice and may minimize the risk of pancreatitis. Precut needle-knife sphincterotomy over a stent is also used to perform accessory sphincterotomy for pancreas divisum.

Selective cannulation of the intrahepatic system (IHBD)   

In a standard short scope position, the angulation of the scope, curvature of the cannula and shape of the CBD all favor cannulation of the right hepatic system. Selective cannulation of the right hepatic system is facilitated by the use of a J-tipped guidewire or a straight guidewire contained in a curved catheter although a curved cannula may sometimes lodge in the cystic duct.

Cannulation of the left hepatic system is more difficult, especially if there is stricture of the left hepatic duct. A straight tip catheter or a right angle tip nasobiliary (NB) tube can be used to aim the guidewire. Inflating an occlusion balloon in the mid common duct and using it as a fulcrum may help to direct the tip of a guidewire into the respective left and right hepatic ducts.

If the axis of the CBD is straight, the tip of the catheter or NB tube is positioned in the distal CBD pointing towards the left side, and a straight guidewire is inserted and directed towards the origin of the left hepatic duct. Rotation of the tip of the endoscope to the left may help to deflect the guidewire into the left hepatic system.

If the axis of the CBD is curved the guidewire usually ends up in the right hepatic duct. It may be useful to try and direct the tip of the catheter or NB tube against the wall of the common hepatic duct on the right side, using the common hepatic duct to deflect the tip of the guidewire into the left system. Also, unwinding a looped guidewire gently at the bifurcation may deflect the tip, thus flipping the guidewire into the left hepatic duct.

If withdrawal of the loop and tip deflection fails it may be helpful to continue pushing the looped guidewire which may back itself into the left hepatic duct. Once the tip of the guidewire is inside the left system, the guidewire is advanced to gain a more secure position before the catheter or NB tube is advanced over the guidewire into the left hepatic duct. It is important to remember that the distal 3 cm of a guidewire is floppy and advancing a catheter over this portion of the guidewire may be difficult.

Pushing a stiff catheter may deflect the guidewire and thus the catheter into the right hepatic system. It is therefore necessary to pass the guidewire further into the desired portion of the intrahepatic system before advancing the catheter over the stiffer portion of the guidewire. Pushing the tip of the scope further into the duodenum may straighten the axis of the bile duct and increase the chance of directing the guidewire into the left hepatic duct.

Cannulation of the papilla in a Billroth II situation(Fig. 17)   

Previous gastrectomy or gastroenterostomy changes the anatomy of the stomach. The approach to the papilla is not through the usual route via the pylorus. Instead the papilla is approached from below via the afferent loop of the gastroenterostomy.

It is worth remembering that the orifice of the afferent loop is usually located to the right of the anastomosis. Rotating the scope for a proper orientation, and turning the patient to the supine position, may help facilitate passage of the endoscope.

In difficult cases intubation of the gastroenterostomy is done by backing the scope into the correct loop. Sometimes biopsy forceps may help the passage or advancement of the scope into the afferent loop. Passage of the scope down the small intestine is similar to doing a colonoscopy with a side-viewing endoscope.

The presence of bile in the lumen does not always predict the afferent loop. It is helpful to monitor the passage of the endoscope on fluoroscopy to determine the direction and position of the scope. It is unlikely that the scope is in the afferent loop if the tip is down in the pelvis on fluoroscopy. The length of the afferent loop may vary and affect the success of reaching the papilla.

In situations where difficulty is encountered or the relevant segment is not clearly defined, it is worth taking a biopsy close to the gastroenterostomy where the bleeding can serve to identify the jejunal segment that has been explored.

The papilla is inverted in the afferent limb and the closed off duodenum appears as a blind stump. Cannulation of the papilla in the inverted position can be difficult. The pancreatic duct is cannulated more readily than the bile duct which comes down in a cephalic and steep axis. A straight cannula gives a better axis for cannulation. For CBD cannulation it is helpful to pull back the scope so that the tip is further away from the papilla and cannulation is done from a distance. This position tends to align the tip of the cannula in the axis of the bile duct.

In most situations the common duct is cannulated with the help of a straight guidewire. Pushing the tip of the cannula against the duodenal wall may deflect the tip of the guidewire in the axis of the CBD. It is useful to have contrast in the pancreatic duct to guide the direction of the guidewire. If no contrast is present in either system it may be necessary to probe the papilla gently with the tip of a guidewire (with about 1cm of the guide wire protruding from the tip of the catheter).

If the guidewire can be inserted deeply into the papilla without any resistance the catheter is advanced over the guidewire. The guidewire is then removed and a syringe is used to suck back from the catheter to confirm its position before injection of contrast. Bile aspirated in the syringe indicates that the bile duct has been cannulated. Aspirate air from the catheter before injecting contrast. When filling the system, begin with normal contrast and inject very slowly. Part of the residual air within the catheter may be pushed into the ductal system which may pose a problem if injected into the pancreas. Air bubbles injected into the bile duct may mimic stones.

Therapeutic ERCP   

Standard endoscopic sphincterotomy or papillotomy (Fig. 18)   

Endoscopic sphincterotomy is a therapeutic application of ERCP, designed to cut the sphincter muscle and open the terminal part of the CBD using diathermy. It was first described in 1973, and is now widely accepted as a therapeutic alternative to surgical management of CBD stones. Endoscopic sphincterotomy is simple, cheap, and more acceptable to patients than surgery. The procedure involves cutting the papilla and sphincter muscle of the distal CBD, therefore sphincterotomy is an incomplete term and the term sphincterotomy is more appropriate.

Preparation of patients   

The preparation of patients for sphincterotomy is the same as for diagnostic ERCP. It can be performed as an outpatient procedure except for patients who have coexisting cholangitis, pancreatitis or significant coagulopathy. Selected patients may need overnight observation in the hospital after sphincterotomy and stone extraction.

Laboratory tests   

Preliminary laboratory tests including blood counts, liver biochemistry and coagulation profile should be taken prior to the procedure. Coagulopathy is corrected when necessary by IV vitamin K injection or transfusion of fresh frozen plasma. Patients are advised to stop taking aspirin, NSAIDs and anticoagulants are withheld for 5 days prior to elective sphincterotomy to avoid bleeding complications. For the patients who require continued anticoagulation for example those with prosthetic heart valve, admission for conversion to intravenous heparin may be required. . The procedure is performed after withholding heparin for 4 h. Anticoagulation therapy is restarted after the procedure.

Antibiotics may be given to patients with coexisting cholangitis and those with significant biliary stasis.

We prefer to use the larger 4.2 mm channel endoscope for therapeutic procedures because it can accept larger accessories.

The sphincterotome (or papillotome)   

Sphincterotomes are available in different designs with some specially designed for altered anatomy following gastric surgery (e.g. Billroth II). In general the sphincterotome is a single or double-lumen Teflon catheter containing a continuous wire loop with 2–3 cm of exposed wire close to the tip. The other end of the wire is insulated and connected via an adaptor to the diathermy or electrosurgical unit. The diathermy unit provides both cutting and coagulation currents, either separately or in combination ( blended mode). The power setting on the diathermy machine can be adjusted. Early single-lumen sphincterotome allows injection of contrast through a single lumen, but leakage occurred around the side ports for the wire. Double-lumen sphincterotomes allow injection of contrast or passage of a guidewire through a separate lumen and can be used for both diagnostic cannulation and sphincterotomy (Fig. 18).

More recent sphincterotomes (e.g. DASH system, Wilson Cook) have a side-arm adaptor that allows contrast injection and insertion of a (0.025 or 0.035 inch) guidewire at the same time. The adaptor can be tightened to close an O-ring around the guidewire to prevent spillage of contrast. The O-ring can be loosened to allow free passage of a guidewire through the sphincterotome. Triple lumen sphincterotomes allow both injection of contrast and passage of a guide wire independently.

Most sphincterotome wires tend to deviate to the right when bowed or tightened, potentially resulting in a deviated cut with an increased risk of complications (i.e. bleeding, perforation, and pancreatitis). It is often necessary to shape the wire to ensure that it remains in the 12 o'clock position when bowed to minimize the risk of complications. When a double or triple lumen sphincterotome is used, it is helpful to insert a guidewire to stabilize the sphincterotome and maintain access into the ductal system during sphincterotomy.

A diagnostic ERCP is performed to define the anatomy of the biliary system and to confirm the presence of stones. Using standard techniques the sphincterotome is inserted deeply into the CBD and its position confirmed either by injecting contrast or wiggling the sphincterotome under fluoroscopy. This is to prevent inadvertent cannulation and cutting of the pancreatic duct. The sphincterotome is withdrawn until only one-third of the wire lies within the papilla. The wire is then tightened so that it is in contact with the roof of the papilla. Excess tension on the wire should be avoided to prevent an uncontrolled or 'zipper' cut. The position of the wire is adjusted and maintained by the elevator bridge and up/down control of the endoscope.

Electrosurgical unit   

A blended (cutting and coagulation) current is passed in short bursts to cut the roof of the papilla in a stepwise manner in the 11–1 o'clock direction. The power setting on different diathermy units varies depending on the energy output of individual units, and has to be adjusted accordingly. For the Olympus diathermy (UES series), the power is set at 3–3.5 with a blended current; the setting on a Valley-lab diathermy machine is 3 of cutting and 6 of coagulation, or a power setting of 30–40 W with a blended I current. The ERBE unit has a unique design that initially coagulates followed by cutting the papilla, the sphincterotomy can be done in a more controlled fashion.

Whitening of the tissue upon passage of current is indicative of the beginning of the cut. If the tissue does not blanch within a few seconds it is necessary to reduce the length of wire in contact with the papilla. It is important to avoid increasing the power setting of the diathermy unit without adjusting or repositioning the wire.

Adequacy of sphincterotomy   

A gush of bile is usually seen flowing from the bile duct when the sphincter is cut. The sphincterotomy is then completed to its full length which is usually 1–1.5 cm. The safe length of a sphincterotomy depends on the configuration of the distal CBD and shape of the papilla.

However, it should not go beyond the impression of the common duct on the duodenal wall in order to avoid a perforation. The size of a sphincterotomy can be gauged by pulling a fully tightened (bowed) knife from within the distal bile duct to assess resistance to passage. An alternative method is to size the sphincterotomy by pulling an inflated occlusion balloon through the opening. Any deformity of the balloon would suggest resistance to its passage.

Wire-guided sphincterotomes   

An advantage of the double or triple lumen sphincterotome is that it can be inserted over a guidewire especially in cases with difficult cannulation. The guidewire also serves to anchor and stabilize the sphincterotome during sphincterotomy. A properly insulated guidewire should be used to prevent the current from jumping between the diathermy wire and the guidewire, leading to an ineffective cut or injury to the liver. Most of the currently available guidewires with hydrophilic coating such as the JAG wire (Microvasive) or Metro Tracer wire (Wilson Cook) can be used for this purpose.

Periampullary diverticula and sphincterotomy   

Diverticula do not increase the risk of sphincterotomy unless the papilla is located on the edge at or inside a large diverticulum. Cannulation may be technically more difficult and the risk of perforation is increased as a result of a deviated cut.

Distorted anatomy   

A previous Billroth II gastrectomy increases the technical difficulty of ERCP and sphincterotomy. Although a forward-viewing scope may facilitate entry into the afferent loop, most experts prefer to use a side-viewing duodenoscope because of the additional elevator control. The success of sphincterotomy in patients with Billroth II gastrectomy is lower than that for patients with normal anatomy. Since the approach to the papilla is through the afferent loop, the orientation of the papilla on endoscopy is reversed. Special sphincterotomes can be used or a needle-knife may be used to cut the papilla over a biliary stent.

Precut sphincterotomy for impacted stone   

In general, deep cannulation of the CBD may fail in 5% of patients, but could be higher because of stone impaction at the ampulla. The biliary orifice is often displaced more distally because of the bulging papilla. In such cases a precut sphincterotomy can be performed using a needle-knife which is basically a bare wire that protrudes for 4–5 mm at the end of a Teflon catheter. A lower power setting on the diathermy unit is often sufficient for precut sphincterotomy.

It is relatively safe to cut directly onto the bulging intraduodenal portion of the papilla. The needle-knife is either placed right at the orifice and the cut is made upwards by lifting the knife, orthe knife is used to cut down onto the papilla by dropping the elevator. The risk of pancreatitis is minimal because the impacted stone pushes the wall of the bile duct away from the pancreatic duct. Once access to the bile duct is achieved, the sphincterotomy can be extended with the needle-knife or using a standard sphincterotome. The impacted stone sometimes may pass spontaneously into the duodenum after an adequate sphincterotomy. Fine control of the needle-knife is difficult and carries an increased risk of bleeding and perforation. It should not be undertaken lightly by an inexperienced endoscopist or used as an alternative to good ERCP cannulation techniques.

Indications for sphincterotomy and results   

Endoscopic sphincterotomy is useful for the removal of residual or recurrent common duct stones in patients with a prior cholecystectomy. The success rate of removing stones <=1 cm in diameter exceeds 95% in expert hands. Patients with large stones may require special treatment such as mechanical lithotripsy (as discussed in a later section).

In elderly or high-risk patients with the gallbladder in-situ sphincterotomy for CBD stone obstruction is indicated especially in those presenting with acute cholangitis. Interval cholecystectomy may be performed but long-term follow-up suggests that cholecystectomy may not be necessary if gallbladder stones are absent. Even for those with gallbladder stones the majority of patients remained asymptomatic on long-term follow-up. Only about 10% of patients develop subsequent biliary symptoms and required further intervention.

Urgent endoscopic drainage with sphincterotomy and/or insertion of a nasobiliary catheter is effective in reducing the overall mortality of suppurative cholangitis. A prospective randomized controlled study confirmed the benefits of urgent endoscopic drainage over emergency surgery.

Sphincterotomy and removal of an impacted ampullary stone is beneficial in patients with severe acute gallstone pancreatitis. A randomized controlled study demonstrated that urgent ERCP and sphincterotomy resulted in a significant reduction in mortality and complications compared to a control group.

Precut sphincterotomy may be indicated in patients with difficult cannulation to gain access to the bile duct for endoscopic biliary stenting. Sphincterotomy also facilitates easier exchange of accessories and double stent placement. It is less commonly applied to treat patients with documented papillary stenosis or sphincter of Oddi dysfunction.

Complications of sphincterotomy   

The results of sphincterotomy are operator dependent. An endoscopist must have sufficient skill and experience with ERCP before attempting sphincterotomy in order to minimize the risk of complications. Bleeding, pancreatitis, and perforation can have serious consequences.

Post sphincterotomy bleeding   

Some bleeding may be observed at the time of sphincterotomy in 2–5% of cases. Clinically significant bleeding is more likely in cases with a deviated cut, a large sphincterotomy and in patients with coexisting coagulopathy. Active bleeding can be controlled by compressing the sphincterotomy with a balloon inflated inside the distal bile duct against the tip of the duodenoscope. Pure coagulation current may be applied to control the bleeding. Injection therapy with 1:10,000 dilution of epinephrine delivered into the apex and side of the sphincterotomy and adjacent tissue using a sclerotherapy needle is also very effective in controlling the bleeding. Injection therapy may give rise to tissue edema and potential biliary stasis. It is therefore necessary to insert a nasobiliary catheter or a stent to drain the bile duct. There may be a risk of pancreatitis if epinephrine is injected close to the pancreatic orifice.

In rare situations major hemorrhage may result from cutting an aberrant branch of the retroduodenal artery. The resultant massive bleeding is difficult to control with endoscopy and may require emergency surgery or radiological embolization of the bleeding vessel. Surgical treatment for postsphincterotomy bleeding is not straightforward since it may be difficult to identify the exact bleeding site and the coagulated tissue does not hold sutures well. The risk of rebleeding is high in patients with clotting disorders and these should be corrected and monitored for up to 7–10 days after the sphincterotomy. Patients should continue to withhold aspirin or NSAIDs for another 5 days to prevent recurrent bleeding.

Pancreatitis   

Pancreatitis may result from inadvertent cutting of or edema around the pancreatic orifice. It can also occur from repeated injection of contrast into the pancreas or excess coagulation during biliary sphincterotomy. Post-ERCP pancreatitis can be reduced by ensuring drainage of the pancreatic duct using a temporary 3 Fr stent or a 5 Fr nasopancreatic catheter.

Cholangitis   

Acute cholangitis is a rare, but important early complication following sphincterotomy. This may occur when contrast is injected into an obstructed biliary system but drainage cannot be established. The risk can be eliminated by drainage of the biliary system with an indwelling stent or nasobiliary catheter.

Perforation   

Perforation is a rare complication of sphincterotomy and may occur as a result of a deviated cut or excessive cutting of the papilla. Patients complain of pain and retroperitoneal free air may be demonstrated on fluoroscopy. If recognized during ERCP, it may be useful to decompress the bile duct with a nasobiliary catheter or an indwelling stent to reduce leakage and the risk of retroduodenal abscess formation. If perforation is suspected after the procedure, CT scan of the abdomen is the most sensitive test in detecting the presence of retroduodenal air.

The patient should be kept nil by mouth with nasogastric tube decompression. Intravenous fluids and broad spectrum antibiotics are given to prevent infection. Patients often respond to conservative management and bowel rest, and surgical treatment is usually not necessary, however, early surgical consultation is wise and percutaneous drainage of retroduodenal fluid collection may be necessary to prevent abscess formation.

What to do if the sphincterotomy fails to cut   

Before the sphincterotomy, it is important to check that the electrosurgical or diathermy unit is working properly, the patient's grounding plate is connected and the correct adaptor is used for the sphincterotome. Poor contact of the grounding plate can be improved using electroconducting gel or gauze soaked with normal saline (not sterile water) placed between the patient and the grounding plate.

If the electrical connections are correct and functional an apparent failure to cut may be the result of having too much wire in contact with the tissue. Withdraw the sphincterotome until only about one-third of the wire is left inside the bile duct. Too little wire in contact with the tissue also produces an ineffective cut. Too much coagulation current leads to formation of a coagulum adherent to the wire and increases the resistance and difficulty in cutting the papilla. It may be necessary to remove the sphincterotome and clean the wire before further cutting or insert the unbowed sphincterotome into the duct to clear the coagulum. Poor contact between the wire and the tissue may also result in ineffective cutting.

As the sphincterotomy is being performed, it may be necessary to gently tighten the wire and lift the sphincterotome with the elevator to maintain contact with the papilla. Whitening of the tissue indicates the beginning of a cut. A lot of smoke without cutting means that insufficient wire is in contact with the tissue or there is too much coagulation. Gently moving the wire to separate the cut edge of the papilla will facilitate further cutting and ensure proper contact with the tissue. In patients with a thick papilla due to stone impaction or a tumor, it may take some time for the wire to cut through. An impacted stone at the papilla may prevent adequate tissue contact.

Too much tension on the wire may result in a sudden jump when the sphincter muscle is completely severed. This uncontrolled or 'zipper' cut is due to excess tension on the wire cutting the relatively thin-walled distal bile duct and is associated with an increased risk of bleeding and perforation.

The risk of a half cut   

When excess coagulum forms, it may be necessary to remove the sphincterotome and to clean the wire. Tissue edema and charring around the sphincterotomy site may make subsequent cannulation of the CBD more difficult. There is a potential risk of dissection through a false tissue plane or submucosal injection of contrast. Using a wire-guided sphincterotome and exchanging over a guidewire prevents this potential complication. Indeed, inserting a guidewire within the bile duct serves also to stabilize the sphincterotome and facilitates exchanges and positioning the sphincterotome.

What to do with a deviated cut   

The risk of bleeding or perforation is increased if the biliary sphincterotomy is performed outside of the 'safety zone', i.e. in the 11–1 o'clock direction. There is a tendency for most sphincterotomy wires to deviate to the right when being tightened, thus increasing the risk of complications.

It is important to check the wire prior to the sphincterotomy. Some sphincterotome have a stabilizing metal plate or differential catheter thickness that allows the wire to exit in the 12 o'clock position (at least in theory). If the wire comes out in a poor direction or orientation it is necessary to train or shape the wire.

The purpose of training the wire is to ensure that it remains in the central position when being tightened. It is done by turning the tip of the sphincterotome 90° so that the wire is on the left side of the catheter tip, curling the tip of the sphincterotome with the fingers while at the same time tightening the wire. This helps to put a memory on the tip of the sphincterotome which keeps the wire in the central position when tightened.

Sphincterotomes come in different designs and shapes, and have different wire lengths. The longer 3.5 cm wire sphincterotomes are more flexible and can be shaped readily and tend to remain in a more neutral position when being tightened. The drawback is that cutting has to be performed with the papilla positioned further away from the tip of the endoscope to avoid the risk of short-circuiting the wire at the elevator. Sphincterotomes with a shorter wire tend to be stiffer and deflect to the right side more readily. One way to compensate for wire displacement is to use sideways angulation to the left or to lean the body to the left or rotating the left wrist to the left, thus displacing the scope to compensate for the malpositioning of the wire. This maneuvre makes use of the side of the wire to cut. An alternative is to angle the tip of the scope downwards away from the papilla and angle left to align the wire in a better axis.

It is necessary to check the direction of the wire frequently during the sphincterotomy to ensure that it stays within the accepted axis. There is a tendency for the wire to fall back into an existing cut despite manipulation, and continuing a misdirected cut will increase the risk of complications. In a displaced papilla sometimes it may be necessary to over-relax the wire or to push instead of tightening to form a loop on the left side. In this position the wire is more likely to make an acceptable contact with the papilla in the correct axis for the sphincterotomy, although the control over the wire is less. A sphincterotome with a rotatable wire may help in correcting the axis of the cut, especially with a distorted papilla.

In order to maintain a proper position for the sphincterotome during sphincterotomy, some endoscopists prefer to use a long-nose sphincterotome so that the wire can be steadied and maintained within the bile duct to minimize the risk of losing the position during cutting. A long-nose sphincterotome is, however, difficult to use for cannulation since the wire is still within the endoscope and cannot be used to provide tension and tip deflection. The use of a double or triple lumen sphincterotome placed over a special coated guidewire may serve the same purpose. Whilst it is best to perform the sphincterotomy in the short scope position, correct orientation may require pushing the scope into a long position.

Sphincterotomy in Billroth II cases   

Approach to the papilla is different in patients with a prior Billroth II gastrectomy. The papilla is seen upside-down when approached from below through the afferent loop. Most of the conventional accessories, including standard sphincterotomes, tend to point away from the bile duct orifice and axis when tightened. This increases the risk of failure as well as complications. The use of a 'reverse' sphincterotome, in which the tip of the sphincterotome and wire is shaped such that it points in the correct direction of the bile duct axis, may be helpful.

Control of the orientation of the sphincterotome is sometimes difficult. The best technique is to place an indwelling stent into the distal bile duct and to use a needle-knife to cut onto the stent in the axis and direction of the bile duct. This provides a correct orientation for the cut and protects the pancreatic duct from injury.

Stone extraction (Figs 19, 20)   

With an adequate sphincterotomy, most stones <1 cm will pass spontaneously. Howeverthe expectant policy carries a risk of cholangitis due to stone impaction and current practice is to remove the bile duct stones to achieve duct clearance at the time of sphincterotomy.

Equipment   

Accessories useful for stone extraction include double-lumen balloon catheters, wire baskets and mechanical lithotriptors. The large through-the-scope mechanical lithotriptor will require the large (4.2 mm) channel duodenoscope.

Procedure   

The stone extraction balloon catheter is an 8 Fr double-lumen catheter with a balloon (8, 12, or 15 mm diameter) at the tip. It is useful to ensure that the balloon inflates correctly prior to insertion. The tip of the balloon catheter is stiff and cannulation may be difficult. It may be helpful to gently curl the tip of the catheter to facilitate cannulation or insert it over a guidewire. The catheter is inserted deeply into the bile duct and the balloon is inflated above the stones. It is useful to try and remove individual stones separately starting at the distal end of the common duct.

With an adequate sphincterotomy, the stone can be pulled down and expelled from the CBD using downward tip deflection of the scope. Care is taken to avoid pulling the balloon too hard against the stone as this may rupture the balloon. As the balloon can be deformed the balloon may slip past the stones resulting in stone impaction. Stone extraction is best confirmed by observing stone passage from the sphincterotomy. Alternatively an occlusion cholangiogram can be performed to document complete clearance of the bile ducts.

Stones can also be removed using a wire basket. The basket is made of four wires and shaped such that the wires open like a trap to engage the stones. The basket is inserted and opened beyond the stones and withdrawn in a fully opened position. The basket is moved gently up and down or jiggled around the stone to trap it. When the stone is engaged the basket is closed gently and pulled back to the papilla. The tip of the endoscope is angled up against the papillary orifice and tension is applied. The stone is extracted by downward tip deflection and right rotation of the endoscope. If necessary, the maneuvre is repeated to remove the stone.

Mechanical lithotripsy

Large (> 2cm) common duct stones are difficult to remove if considerable discrepancy exists between size of stone and diameter of the exit passage i.e. a narrowed distal bile duct, a small sphincterotomy and in those who had only balloon sphincteroplasty for stone extraction (Fig. 21) Extension of the sphincterotomy is not always possible and may carry an increased risk of bleeding and perforation. Lithotripsy facilitates stone extraction and common duct clearance by crushing the stones with using strong wire baskets before extraction.

There are different designs for lithotripsy baskets - one type requires cutting the handle of the basket and removing the endoscope prior to stone fragmentation, e.g. Soehendra lithotriptor (Wilson Cook Medical, Winston Salem, NC). This consists of a 14 Fr metal sheath and a self-locking crank handle. The lithotriptor can be used with large lithotripsy baskets or standard stone extraction baskets. These are typically four wire hexagonal baskets measuring 2 by 3 cm, or 3 by 5 cm in diameter. (Fig. 22).

Another type is a pre-assembled through-the-scope lithotripsy basket which can be inserted through a therapeutic duodenoscope, e.g. BML lithotripsy baskets (Olympus Co, Tokyo, Japan). The BML lithotriptor has three layers - a strong four wires basket, a Teflon catheter, and an overlying metal sheath. The reusable version requires assembly by inserting the Teflon catheter initially through the metal sheath and then loading the basket retrogradely on to the Teflon catheter. The wires are soldered together on to a shaft which is connected to the crank handle. Contrast is injected via the Teflon catheter. The opening and closing of the basket is controlled with the handle. Stone engagement is performed with the Teflon catheter and basket. The metal sheath is usually advanced over the Teflon catheter up to the level of the stone when lithotripsy is required. Traction is applied to the wires by turning the control wheel in order to crush the stone. As the control does not have a built-in locking mechanism, traction should be applied slowly and continuously to allow time for the wires to cut through the stone.

The reusable system can be taken apart after lithotripsy for cleaning and sterilization. The disposable version comes with the lithotripsy basket, Teflon catheter and metal sheath all built into one. The set-up is designed to break at the connection between the basket and the crank handle. The basket wires are also designed to break at the tip to prevent having a broken basket around an impacted stone in the bile duct. The larger lithotripsy baskets or BML-3Q equivalent have a slightly thicker metal sheath that goes through a 4.2 mm channel scope, contrast injection is possible. The smaller basket or BML-4Q equivalent goes through a 3.2 mm channel scope but contrast injection is difficult because of the small size (Fig. 23).

The Monolith (Microvasive, Boston Scientific, Natick, MA) is a single-piece disposable mechanical lithotriptor with the basket, metal sheath and crank handle all built into one. The basket is inserted to engage the stones in the bile duct. Traction to the wires is applied by a self-locking pistol grip mechanism. Three sizes of baskets are available and the commonly used basket size is 2 cm by 4 cm.

Procedure

The Soehendra lithotriptor is used when unexpected stone and basket impaction occurs during routine stone extraction and that is why it is often called the "life saver". The handle of the basket is cut and the duodenoscope is removed. The metal sheath is then railroaded over the basket wires. It is helpful to retain the Teflon sheath to facilitate insertion of the metal sheath and to prevent the bare wires from being caught at the tip of the sheath. A tape can be used to round off the tip of the sheath to prevent injury to the posterior pharynx. The metal sheath is advanced all the way to the level of the stone under fluoroscopic control. The basket wires are then tied around the shaft of the handle and traction applied slowly. This allows time for the wires to cut through and break up the stone. This device is the best method to salvage a complication of stone and basket impaction. It is important to remember that stone may be trapped in a standard basket which is not designed for lithotripsy. Therefore, traction applied too quickly to the wires may break the basket and not the stone.

The BML lithotripsy basket can be used in anticipation of lithotripsy for large common duct or intrahepatic stones above a strictured bile duct. Initial cannulation of the common duct is performed with the basket after an adequate sphincterotomy or balloon sphincteroplasty. The metal sheath is retracted within the scope channel and only the Teflon catheter and basket are used to engage the stone. The basket is opened beyond the stone and pulled back to engage the stone. Trapping of large stones may be difficult because of lack of space within the bile duct for basket manipulation. Shaking the basket may not work. If necessary, the metal sheath is advanced up the Teflon catheter to provide more stiffness for manipulation of the basket. Gentle twisting or rotation of the scope may facilitate movement of the basket wires around the stone. Advancing the scope further into the duodenum straightens the axis of basket and the bile duct and facilitates stone engagement. When the stone is properly trapped in the basket, the metal sheath is advanced up to the stone by adjusting the control on the shaft of the lithotripsy basket. Traction is applied to the wires by turning the control wheel to crush the stone. In case of a very hard stone, the basket wires are deformed after stone fragmentation. It should be removed and the wires shaped to reform the basket before further stone engagement. As the stone fragments may still be relatively large, repeated stone crushing is necessary to facilitate stone extraction and duct clearance. As discussed above, the disposable system BML-201, 202, 203, and 204 are used in a similar fashion.

The Monolith lithotriptor is inserted through the duodenoscope, the metal sheath is advanced into the bile duct and the basket opened and pulled back to engage the stone. Contrast can be injected to define the position of the stones. Once the stone is engaged, traction is applied to the wires to crush the stone. As the basket wires can become deformed, reshaping the wires is necessary before lithotripsy is repeated. Mechanical problems including failure of proper opening of the basket and damage to the scope elevator have been reported.

Results

The new lithotripsy baskets are strong and successful mechanical lithotripsy depends mostly on effective trapping of the stone. Lithotripsy may fail in the presence of stone impaction or if there is insufficient room in the CBD for manipulation of the basket. Partial fragmentation of a very large stone may be possible although the wires may tend to slip around the stone. Repeated stone crushing is necessary to break up the large fragments. The reported success rate of mechanical lithotripsy for large stones ranged from 85% to 90%, improving the overall common bile duct clearance rate to over 95%.

Complications of lithotripsy

The Soehendra lithotriptor provides effecive crushing of the stone in unexpected cases with stone and basket impaction. However when a standard basket is used for stone extraction, the basket wires may break in the duodenum resulting in stone and a broken basket impacted in the bile duct. Such cases may require surgical common duct exploration to deliver the impacted stone and basket. Special precaution including slow application of traction to the wires may prevent this complication.

With the BML system, the baskets are made to break at the connection of the shaft with the handle. When this happens, Olympus has made a special metal oversheath and a crank handle similar to the design of the Soehendra lithotriptor. The standard metal sheath of the lithotriptor basket is replaced by this special metal sheath before stone fragmentation is continued. We do not recommend adapting the Soehendra lithotriptor handle to the BML basket for lithotripsy.

Perforation is an uncommon event and rarely occurs as a result of the stiff basket perforating the bile duct. Excessive force in removing the impacted basket and stone may result in bruising of the pancreatic orifice and a potential risk of pancreatitis. Incomplete CBD clearance without adequate drainage may result in cholangitis due to retained stone fragments. Forceful extraction of large stones fragments should be avoided to minimize risk of scope trauma to the duodenum.

Endoscopic nasobiliary catheter drainage for bile duct obstruction (Fig. 24)   

There are several ways to decompress an obstructed biliary system. In patients with acute suppurative cholangitis secondary to stone obstruction endoscopic sphincterotomy and insertion of a nasobiliary catheter provides effective decompression with dramatic improvement of the clinical condition. The nasobiliary catheter is relatively easy to insert and is well tolerated for a few days. It allows sequential cholangiography, bile culture and irrigation. Naso-gallbladder drains have been inserted with the help of special guidewires for the drainage of acute cholecystitis.

Procedure   

Following a diagnostic ERCP, deep cannulation of the bile duct is obtained using a 0.035 inch guidewire. A nasobiliary catheter is a 6.5–7 Fr polyethylene tube (260 cm in length) with a preformed tip and multiple side-holes in the distal 10 cm. It can be inserted into the biliary system over the guidewire with or without a prior sphincterotomy. Direct cannulation is sometimes possible using a nasobiliary catheter with a right angle tip. The guidewire helps to bypass the obstructing stones and position the tip of the nasobiliary catheter deep in the bile duct.

Once the nasobiliary catheter is in place the endoscope is withdrawn slowly leaving the catheter and guidewire in the bile duct. This exchange is done under fluoroscopic control to avoid excess looping of the catheter in the duodenum. A nasopharyngeal or nasogastric suction tube (rerouting tube) is inserted through a nostril and brought out through the mouth.

The end of the nasobiliary catheter is inserted through this tube until the proximal end of the catheter appears in the nasopharyngeal tube. The nasobiliary catheter together with the nasopharyngeal tube is pulled back through the nose. Care is taken to avoid looping and kinking of the nasobiliary catheter in the posterior pharynx. The nasobiliary catheter is then connected to a three-way adapter and the bile ducts decompressed by aspirating bile. A bile specimen is sent for culture. The final position of the nasobiliary catheter is checked under fluoroscopy and anchored by taping to the face. The catheter is then connected to a drainage bag.

Temporary stenting may be helpful when large stones cannot be extracted (Fig. 25)

Endoscopic plastic stent insertion for malignant biliary obstruction (Fig. 26)   

The technique of endoscopic insertion of biliary stents was first described in 1979. It is now an established method for the palliation of malignant obstructive jaundice. This is especially useful in patients with carcinoma of the pancreas as fewer than 20% of patients are appropriate for surgical resection, and less than 1% survives for more than 5 years.

Equipment   

Side-viewing duodenoscopes with a 3.2 mm channel are necessary for insertion of 7–8 Fr stents. Larger 4.2 mm channel endoscopes are available for insertion of 10 and 11.5 Fr stents. The most commonly used plastic stents are straight with flap anchorage systems.

The standard applicator system consists of a 0.035 inch guidewire (480 cm) with a 3 cm flexible tip, and a 6 Fr radiopaque Teflon (260 cm in length) guiding catheter with a tapered tip to facilitate cannulation. Some guiding catheters have two metal rings (placed 7 cm apart) at the distal end for ease of identification and for measuring the length of the stricture.

The outer pusher tube is made of Teflon (8, 10, and 11.5 Fr) and used for positioning the stent during deployment. Stents are made of 7, 10, or 11.5 Fr radiopaque polyethylene tubes. They vary in length between the two anchoring flaps (5, 7, 9, 10, 12, 15 cm). There is no inner catheter for the 7 Fr stenting system.

Other stents have double pigtails that serve to anchor the stent to prevent upward or downward migration. However the straight stent with side flaps is preferred because it maintains its position with infrequent dislocation. It provides maximal flow and minimizes the risk of blockage compared with the double-pigtail stents, which have a smaller lumen and side holes.

Preparation of patient   

The resectability of the underlying cancer or lesion and the clinical condition of the patient should be carefully assessed prior to stenting. Initial investigations include liver function tests, abdominal ultrasound and CT scanning to define the nature and level of obstruction. Endoscopic ultrasound and fine-needle aspiration biopsy are also useful for staging and diagnosis of the underlying cancer. MRCP may be necessary in cases of hilar obstruction to outline the obstructed ductal system.

Coagulation defects are corrected by IV Vitamin K₁ and/or fresh frozen plasma. Prophylactic antibiotic may be given before the procedure.

Procedure   

Preparation and sedation of the patient are the same as for standard ERCP procedures. A diagnostic ERCP is performed and the level of obstruction defined. Sphincterotomy is not necessary for placement of a single stent but is useful to facilitate insertion of multiple stents, and may prevent the complication of pancreatitis following stenting for hilar strictures caused by pressure of the stents against the pancreatic orifice.

Initial cannulation and insertion of the guidewire past the stricture can be performed using standard accessories. It is preferable to use a guide wire with a hydrophilic tip for easy passage through the stricture. Brush cytology can be taken by exchanging the cyotology brush over the guide wire. The guiding catheter is then exchanged over the guidewire to bypass the obstruction. The guidewire is then removed and additional bile samples can be aspirated for culture and cytology. The length of the stricture is determined on cholangiography with the help of radiopaque ring markers.

A suitable length stent is chosen so that the proximal flap of the stent lies about 1 cm above the obstruction. The optimal length of the stent can be determined by measuring the separation between the proximal obstruction and the level of the papilla on the radiographs. It can be estimated with reference to the scope diameter or by using the radiopaque markers on the inner catheter. The correct length of the stent is determined by correcting for the magnification factor of the fluoroscopy unit. The stent length can also be determined by retracting the guidewire between the two points and measuring the distance traveled on the outside of the catheter.

The stricture may be dilated (when particularly tight) prior to stent insertion with graded dilators or pneumatic balloon dilators (4, 6, 8 mm) inserted over the guidewire. The stent is loaded onto the catheter or guidewire and then positioned through the obstruction with the help of the pusher tube. The stent is deployed by removing the inner catheter and guidewire. Bile is seen draining through the stent into the duodenum. The pusher is then removed.

One-step introducer system   

A modified introducer system combines the inner catheter and pusher into a single system using a Luer lock mechanism. A suitable length stent is preloaded on to the introducer system and inserted over the guidewire, and positioned through the obstruction. Once the inner catheter is in position, the pusher and inner catheter are unlocked and the stent is pushed and deployed across the obstruction by withdrawing the inner catheter and guidewire.

Bilateral stenting for hilar obstruction   

Hilar tumors pose difficult technical problems. Whether it is necessary or desirable to drain all obstructed ducts remains controversial. When one duct is dominant draining it alone may be sufficient. To drain both the right and left hepatic systems, it is necessary to insert two guidewires separately. Correct anchorage of the guidewires is necessary because of the potential for dislodgement during exchange of accessories. This can be achieved using either a hemostat to clip the wire to the biopsy valve or by using a special anchoring unit that comes with a particular stenting system.

We recommend performing routine balloon dilation of hilar strictures prior to stent insertion as they are often very tight. It is better to start with the left hepatic system due to the more difficult access and axis with stent insertion.

Once the left stent is in place another straight stent is introduced into the right side to drain part or all of the right hepatic ducts. Care is taken not to push the first stent into the bile duct during insertion of the second stent. In general successful drainage of the left hepatic system alone may result in improvement of the liver function. The left hepatic duct branches off after 2 cm in contrast to the right hepatic duct which branches off after 1 cm.

Multiple segment obstruction is more likely to occur on the right side. Successful drainage and recovery of liver function is therefore more difficult due to the limited volume of liver tissue drained by the individual segmental hepatic ducts. Some endoscopists recommend multiple stents in all cases to achieve complete drainage.

Every attempt should be made to avoid overfilling the intrahepatic system to minimize the risk of sepsis. If endoscopic drainage fails percutaneous transhepatic drainage of the obstructed system may be considered and the combined percutaneous and endoscopic approach (or rendezvous approach) may be helpful on rare occasions.

Brushing cytology for bile duct strictures (Fig. 27)   

Single-lumen system   

Brush cytology can be taken after passing a guidewire through the obstruction. The sheath of the cytology brush can be inserted over the guidewire through the stricture. The guidewire is then removed and the cytology brush inserted through the sheath. The sheath is then pulled back to allow the brush to emerge into the dilated proximal system. The brush and catheter are then pulled back through the stricture. An X-ray is taken to document the position of the brush through the stricture. Care is taken to ensure that the guidewire tip remains above the obstruction.

After the brush is pushed and pulled through the stricture several times the catheter sheath is advanced back into the proximal dilated system, the brush is removed and the tip prepared for cytology. The guidewire is then replaced and the cytology sheath exchanged for the inner catheter. The rest of the stenting procedure is completed in the usual manner.

Using the single-lumen cytology system cell loss is inevitable because the brush is pulled back through the whole length of the catheter. It is useful to aspirate bile from the catheter to collect any dislodged cells within the catheter to improve the diagnostic yield.

Double-lumen system   

Double-lumen cytology brush systems allow the guidewire to pass through the central lumen of a tapered tip catheter and the cytology brush exits from the side lumen near the tip. With the brush in the retracted position the catheter is inserted over the guidewire through the obstruction. With the help of radiopaque markers the cytology brush is advanced from the catheter into the dilated proximal system. The entire apparatus is then moved back and forth through the area of the stricture to obtain samples. An X-ray is taken for documentation.

The brush is then withdrawn into the catheter and the whole set-up exchanged over the guidewire without having to pull back the brush completely. This set-up ensures access is maintained across the stricture by the guidewire for the ease of subsequent stenting or drainage and also avoids cell loss. When the brush is withdrawn the tip of the brush is cut off and saved in the cytology solution. It is useful to remove the stylet and flush air or water through the channel of the brush to remove any fluid inside for cytological examination.

Assessment of response to biliary stenting   

The clinical course of the patient is a good guide to the function of the stent. With successful drainage pruritus usually disappears in 1–2 days as jaundice begins to resolve. Serum bilirubin declines by a mean of 2–3 mg/dl per day. With distal bile duct obstruction bilirubin levels may return to normal levels after 1–2 weeks. Incomplete or slow recovery of liver function may be related to prolonged obstruction which affects hepatocyte function or due to inadequate or incomplete drainage because of multiple segment involvement, as in hilar obstruction. Presence of an air cholangiogram suggests stent patency which can also be assessed by an EHIDA scan. Delayed appearance of the radioisotope in the biliary system and intestine with appearance of radioisotope in urine, suggests stent blockage.

Results of biliary stenting   

The success rates for biliary stenting vary depending on the level of obstruction. It is high for mid- or distal CBD obstruction and lower for hilar obstruction. The success rates for draining both the right and left hepatic systems are low in patients with bifurcation lesions. Failure of endoscopic stenting may be due to tumor compression and/or distortion of the duodenum, marked displacement of the papilla or failure of insertion of the guidewire through a very tight stricture.

Complications of stenting   

Early complications   

Early complications of stenting include pancreatitis, bleeding if a sphincterotomy is performed, cholangitis in patients with bifurcation tumors and early stent blockage by blood clots. Guidewire perforation through a soft and necrotic tumor has been reported.

Late complications   

Late complications are largely due to stent blockage by bacterial biofilm and biliary sludge, resulting in recurrent jaundice and cholangitis. Stent dislocation and traumatic ulceration of the duodenum by the distal tip of the stent may occur. Acute cholecystitis secondary to stenting is a rare complication.

Recurrent jaundice is a major late complication of endoscopic stenting. Tumor extension may account for a small proportion of cases. The most important cause is clogging of the lumen of the stent by biliary sludge. Sludge consists largely of calcium bilirubinate and small amounts of calcium palmitate, cholesterol, mucoprotein, and bacteria. Bacterial infection is important in initiating sludge formation through adherence and formation of a bacterial biofilm. The likely source of bacteria is ascending infection from the duodenum via the stent or descending infection through the portal system. The bacteria are mostly large bowel flora.

Different methods have been tested to prevent stent blockage. Larger-lumen stents delay the onset of clogging. Stent exchange at regular intervals also prevents the clinical risk of blockage. Antibacterial plastics and prophylactic antibiotics have not produced any clinically significant benefits. An alternative solution to the blockage of plastic stents is to use self-expandable metal mesh stents.

Self-expandable metal stents   

Self-expandable metal stents (SEMS) were introduced as a means of prolonging stent patency. SEMS expand to 1 cm diameter and do not become obstructed by bacterial biofilm. However metal stent occlusion does occur, but mostly as a result of tumor/tissue ingrowth or overgrowth.

Stent configurations   

The commonly used SEMS have an open mesh design. Variations include the Wallstent, the Diamond Stent, the Spiral Z-Stent, the Za-Stent and the more recently introduced Zilver stent. SEMS are made of surgical-grade stainless steel or nitinol, a nickel–titanium alloy that provides a high degree of flexibility and is kink resistant. However nitinol is less radiopaque than stainless steel and additional radiopaque (gold or platinum) markers are put on the stents to improve radiopacity to facilitate proper positioning during deployment. Covered SEMS are now available. One example is the Wallstent (Microvasive) which has a polymer (Permalune) coating on the inside of the stent except for the proximal and distal 1 cm. This membrane is designed to prevent tumor ingrowth and prolong stent patency.

Lengths of stents   

SEMS usually come in 2–3 different expanded lengths (e.g. 4.8, 6.8, and 8.0 cm for the Wallstents, 5.7 and 7.5 cm for the Spiral Z-Stents). The Wallstent foreshortens after deployment to about two-thirds of its collapsed length when it is fully expanded. The Spiral Z and Zilver stents do not shorten after deployment.

Introducer system for SEMS   

In general the wire mesh metal stents are collapsed and restrained on a 6–6.5 Fr introducer catheter by an 8–8.5 Fr overlying plastic sheath. Smaller 7/7.5 Fr introducer systems are now available. Sterile water or saline is initially injected to flush the system to minimize friction between the stent and the restraining sheath and to facilitate stent deployment. The whole system is placed over the guidewire and advanced through the obstruction.

With the stent correctly positioned across the stricture the overlying sheath is pulled back while the handle is held steadily to hold the introducer catheter and guidewire in position. The stent is deployed slowly in a stepwise manner. Stent deployment can be monitored under fluoroscopic control using the radiopaque markers. Adjustment of the stent position may be necessary before complete deployment, especially for stents that foreshorten, e.g. the Wallstent. It is also easier to pull back than to advance a partially deployed stent through the stricture or obstruction.

Metal stents are usually placed with the distal tip in the duodenum for distal bile duct obstruction. Due to the limited lengths available the stent can be placed completely inside the CBD for proximal or mid-duct strictures. It is important to avoid leaving the distal tip of the stent just at the level of the papilla as this can cause discomfort and dysfunction.

Balloon dilation of biliary strictures (Fig. 28)   

Both malignant and benign bile duct strictures may present with obstructive symptoms. Patients with dominant extrahepatic strictures complicating primary sclerosing cholangitis (and some with chronic pancreatitis) may respond to balloon dilation of the strictures with or without use of biliary stents. A stenosed choledochoduodenostomy may be safely and effectively dilated using a pneumatic balloon dilator. Similarly, balloon sphincteroplasty using a pneumatic balloon has been used to facilitate removal of small CBD stones without a sphincterotomy.

Equipment   

Balloon dilation is best performed with a large channel endoscope. Additional accessories include the pneumatic balloons. These are made of non-compliant polyethylene with two types available. One type goes over a guidewire while the other type the TTS (through the scope) balloons does not require a guidewire. Balloons come in different sizes and lengths: 4, 6, or 8 mm in diameter and 2–6 cm long.

Procedure   

A prior sphincterotomy is not necessary but may facilitate the introduction of large balloon catheters and exchange of accessories. A flexible tip guidewire is inserted with the help of a catheter and negotiated through the stricture. The catheter is removed and the dilation balloon is railroaded over the guidewire across the stricture. The balloon is positioned so that the stricture lies at the midpoint of the balloon. The presence of radiopaque markers helps in positioning the balloon.

The balloon is then inflated with dilute (10%) contrast and the pressure adjusted according to the type of balloon and manufacturer's recommendation. The dilation is performed under fluoroscopy and a waist is seen at the midpoint of the balloon upon inflating the balloon. Effective dilation is achieved when the waist disappears.

The patient may experience pain during insufflation of the balloon. The balloon is usually kept inflated for 30–60 sec and then deflated. It is helpful to reinflate the balloon and note the opening pressure when the waist disappears on the balloon. With successful dilation the opening pressure should be lower with repeat dilation. The balloon is then completely deflated, the guidewire removed and contrast injected while the balloon catheter is pulled back to assess the effect of dilation.

Balloon dilation facilitates stent insertion in patients with malignant biliary strictures. The short-term effects of balloon dilation for benign biliary strictures are good but long-term follow-up shows some restenosis. Repeat dilation at regular intervals may be necessary to keep the stricture open. Some endoscopists advocate the use of temporary stenting (with multiple stents) to keep the stricture open and repeat dilation and stent exchange every 3 months for up to a year. Intrahepatic bile duct stones have been successful removed following balloon dilation of intrahepatic strictures.

Endoscopic management of bile leaks   

Bile leaks may arise from the cystic duct stump after a cholecystectomy or from injury to the CBD during surgery. Patients usually present with persistent bile drainage or formation of a biloma. As bile tends to flow in the path of least resistance an intact papilla maintains a positive intrabiliary pressure and may perpetuate the leak. Eliminating or bypassing the sphincter mechanism may reduce the intrabiliary pressure.

Alternatively an indwelling nasobiliary catheter or stent which bypasses the sphincter may serve to decompress the biliary system and promote healing of the leak. A small leak can be closed off easily by nasobiliary catheter drainage for a few days. Bile leak associated with CBD damage may require placement of an indwelling stent across the leak for up to 4–6 weeks. It is important to check for residual damage or stricture of the CBD after removal of the stent.

 Outstanding issues and future trends   

ERCP now plays a very important role in the imaging and therapy of different pancreatico-biliary problems. Many different technologies are being developed to shorten the time of the procedure by improving access and success with selective deep cannulation thus minimizing manipulation within the ductal systems.

ERCP is however not without risk and serious complications have been reported. Acute pancreatitis remains an important complication of this procedure and can occur even after a simple diagnostic cannulation. Although we are able to identify individuals who are at increased risk, currently available methods are not very effective in preventing this complication. Prophylactic pancreatic stenting to improve drainage is promising but this procedure itself requires considerable skill and experience.

MRCP with improved resolution may well replace diagnostic ERCP. However ERCP will continue to play a role in management of pancreatico-biliary diseases because of its therapeutic applications. There is a potential concern that with the limited number of cases and the high skill level required of a biliary endoscopist, we may see a significant reduction in the number of trained endoscopists in the future. We are already seeing a reduction in the number of training positions and expectation of additional (third-tier) training before one becomes qualified to perform these procedures. The question of whether training with simulators may improve the skill of the biliary endoscopist remains to be addressed.

 References  

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