Synonyms Endoscopic Retrograde Cannulation of Ampulla of Vater; Endoscopic Retrograde Cannulation of Pancreas; Endoscopic Retrograde Cannulation of Papilla of Vater; ERCP

Applies to Esophagogastroduodenoscopy (EGD); Percutaneous Transhepatic Cholangiogram (PTC)

Procedure Commonly Includes Endoscopic visualization of the duodenum and papilla of vater, followed by radiologic assessment of the pancreatic duct and biliary tree. Procedure is performed on a conscious, but sedated patient. A specialized fiberoptic endoscope is introduced by mouth and advanced through the upper GI tract until the second portion of the duodenum is reached. Under direct visualization the papilla of vater is located and inspected. A small catheter is then advanced through the papilla of vater and into the pancreatic and biliary duct systems, all under fluoroscopic guidance. Contrast material is injected through the catheter, outlining the pancreatic duct (pancreatogram) and biliary ducts (cholangiogram). Forceps biopsies or cytologic brushings of the periampullary region and ducts may be taken. Endoscopically-guided therapeutic procedures are also possible, including endoscopic sphincterotomy and dissolution of stones. ERCP is a safe, nonsurgical means of assessing the anatomy of the ductal system and is successful in 80% to 90% of attempts.

Indications ERCP has emerged as a widely accepted, standard technique for diagnosing a variety of pancreaticobiliary tract disorders. However, several noninvasive radiologic procedures are also effective in diagnosing these disorders, including percutaneous transhepatic cholangiography (PTC), CT scan of the abdomen, ultrasound of the abdomen, and the radionuclide liver-spleen scan. These imaging techniques should be considered complementary (not competitive) with ERCP. The precise sequencing of studies must be individualized in each case, but generally the high-risk procedures (ERCP, PTC) are reserved for last. With these considerations in mind, the American Society for Gastroenterology (1986) published suggested guidelines for ERCP as follows:¹

ERCP may also be useful in:

ERCP is less useful in the following situations:²

Therapeutic application of ERCP includes:

Contraindications

Relative contraindications include:

Patient Preparation Technique and potential complications of the procedure are discussed with the patient. Informed consent is obtained for ERCP, including likely therapeutic interventions. Formal consultation with gastroenterology staff is required prior to approval and scheduling. Patient is informed whether overnight hospitalization is necessary (most cases) or whether "same day" outpatient ERCP is feasible. On the day prior to the procedure, inpatient candidates are routinely seen by the endoscopist (or his representative) to briefly examine the patient, review details of the case, write orders, and answer remaining patient questions. Patient is made NPO after midnight (or at least 8 hours prior to study). Daily oral medications are permitted on the morning of ERCP with physician approval. Exceptions include antacids and CarafateŽ which may interfere with visualization of the mucosa. Aspirin products and nonsteroidal agents must be discontinued well in advance (at least 5 days for aspirin), especially if biopsy or sphincterotomy/papillotomy is anticipated. For hospital inpatients, dentures are removed and patient is transported to endoscopy suite on cart, accompanied by medical chart and relevant x-rays. For outpatients, procedure is the same except that transportation home must be arranged in advance if a "same day" procedure (driving not permitted due to sedative effects). Once patient is in the procedure room, baseline vital signs are recorded and an intravenous line started. Antibiotic prophylaxis may be given at this time (see Special Instructions). Premedications are routinely given including parenteral meperidine, diazepam, and often atropine (0.4 mg). A topical anesthetic agent such as CetacaineŽ spray is applied to the pharynx.

Aftercare The patient is placed at strict bedrest and observed carefully in the recovery area. Vital signs are monitored frequently and physician contacted if any complications arise. If the patient has tolerated the procedure well, he may be discharged from the testing area once sedatives have worn off. NPO until gag reflux has returned, then clear liquids for 24 hours. Any patient undergoing a therapeutic procedure should be observed overnight in the hospital. If a "same day" outpatient procedure (not allowed in all institutions), patient must have ready access to the hospital emergency room should complications develop.

Special Instructions Prior to ERCP, if bile duct obstruction is suspected, antibiotic coverage is usually indicated. If high grade bile duct or pancreatic duct obstruction is confirmed during ERCP, antibiotics should be continued (or begun). Individuals at risk for infective endocarditis are often given antibiotic prophylaxis prior to ERCP, particularly if a therapeutic maneuver such as sphincterotomy is planned. High risk cardiac lesions include rheumatic valvular disease, prosthetic valves, and prior endocarditis. However, ERCP is considered a relatively low risk procedure for the development of endocarditis, in comparison with invasive dental procedures and genitourinary tract instrumentation. Some authorities feel that prophylactic antibiotics are not warranted. A controlled clinical trial to answer this question is unlikely and liberal use of prophylactic antibiotics will probably continue.

Complications In the hands of a skilled endoscopist, diagnostic ERCP is associated with a 3% incidence of morbidity and 0.2% mortality, based on nationwide statistics.³ Complication rate is considerably higher with an inexperienced endoscopist. If endoscopic sphincterotomy or papillotomy is performed, overall morbidity rate increases to 8% and mortality 1% to 1.5%. Emergent surgical repair is necessary in 2%; it should be noted that these figures are superior to those documented for elective surgical exploration of the common bile duct.

Complications of ERCP may be classified as follows.

Equipment The duodenoscope used for ERCP is similar to the fiberoptic endoscope used for EGD with several modifications. The viewing lens and light window at the instrument tip are arranged for side viewing. Within the duodenoscope is a channel which can accommodate a polyethylene contrast-filled catheter, which can be advanced past the tip of the instrument; this separate catheter is used for cannulating the papilla of vater. Other devices may be passed through the endoscope including biopsy forceps, electrocautery devices, sphincterotome, cytology brush, etc. A teaching head may be used for additional viewing or the endoscopic images may be videotaped on a television monitor.

Technique ERCP is performed with the patient on an x-ray table with radiologic equipment and fluoroscopy at hand. Following premedication the patient is placed in the left lateral decubitus position. The duodenoscope is passed by mouth through the anesthetized pharynx, and into the esophagus, stomach, and duodenum. A rapid visual examination of these segments may be made. Once the instrument has reached the second (descending) portion of the duodenum, the ampulla of vater is located, often on the medial wall. The periampullary region is carefully inspected. Often glucagon is given (0.2 mL doses) to decrease duodenal motility and facilitate visualization. The inner catheter (containing contrast dye) is then advanced from the lateral port of the endoscope and guided into the orifice. Once the ampulla has been engaged, the catheter is advanced several millimeters into the duct and a small volume of contrast injected. The dye filling pattern is observed under fluoroscopy ("the test shot") to determine orientation. In this manner the pancreatic duct and the bile duct may be selectively cannulated and imaged separately with contrast. Fluoroscopy is used as needed to assure proper catheter orientation. Formal spot radiographs are taken of contrast-filled ducts for the permanent record. At times x-ray table adjustments and patient repositioning may be necessary particularly if the gallbladder is imaged. Delayed films are also obtained following removal of the duodenoscope since contrast material normally remains in the ductal system for minutes. In addition, suspicious periampullary or ductal lesions may be biopsied and cytologic brush samples obtained. "Blind" biopsies of the ducts and/or pancreas may be taken at physician discretion. A variety of therapeutic procedures, mentioned earlier, may be performed.

Specimen Biopsy specimens and cytologic brushings are placed in appropriate containers and fixatives and sent to pathology laboratory without delay. Tissue for Gram's stain and culture is placed in a sterile jar without fixative and hand carried to the Microbiology Laboratory. Details of specimen collection, fixative, and transportation are handled by the gastroenterology team.

Turnaround Time Final report on biopsy and cytology specimen histology is given within 2-3 days (or longer in some cases).

Normal Findings Preliminary written report on endoscopic and radiologic findings immediately completed by gastroenterology staff. Final typewritten report is added to the chart in several days. A "normal cholangiogram" implies a normal radiographic appearance of the following structures: common bile duct (CBD), common hepatic duct, left and right hepatic duct (and subdivisions), cystic duct, and gallbladder. Maximum diameter of the normal CBD is approximately 9 mm (range 4-9 mm) providing the gallbladder is present. If the patient has had prior cholecystectomy, diameters may be somewhat increased. The CBD normally will have a tapered appearance at its distal end, the so-called "vaterian segment" where it is surrounded by the papilla and sphincter of Oddi. A "normal pancreatogram" implies a smooth, patent main pancreatic duct which gradually tapers from the body (diameter 3.4 mm) to the tail (1.7 mm). With optimal filling of the pancreatic duct, approximately 15-30 secondary branches will be outlined with contrast. These are straight in appearance and of fine caliber. There is variability in the anatomy of the pancreatic ducts. For example, the duct of Santorini is present in 80% of normal individuals and its communication with the duodenum or main pancreatic duct is variable.

Critical Values In formulating the diagnostic impression, information is obtained from three sources: direct visual examination, radiologic imaging, and biopsy specimens. Endoscopic examination of the papilla of vater may reveal a mucosal mass if carcinoma of the pancreatic head is present. Other malignancies may involve this region including ampullary carcinoma, cholangiocarcinoma, and rarely duodenal cancers. The endoscopic appearance of the papilla may be highly suggestive in other disease states, such as papilla "bulging" (possible impacted stone), edema, erythema, and patency (recently passed stone), visible purulent drainage (suppurative cholangitis), bright red blood through the orifice (hemobilia). Radiologic abnormalities in the cholangiogram may be specific and diagnostic. Certainly, retained stones in the common bile duct are easily recognized by discrete filling defects. Other deviations include biliary strictures, irregular filling defects or mass lesions beyond endoscopic visualization (carcinoma), ductal dilatation (obstruction of any cause), irregular intrahepatic ducts with strictures and ectasia (sclerosing cholangitis), cystic duct narrowing with cholelithiasis (acute cholecystitis). The pancreatogram may reveal congenital abnormalities (such as pancreas divisum), small pancreatic pseudocysts (not seen on CT scan), and pancreatic duct calculi. The radiologic appearance of carcinoma of the pancreas includes:

The radiologic appearance of chronic pancreatitis may closely resemble pancreatic cancer. However, the main pancreatic duct in chronic pancreatitis is classically irregular, tortuous, and with multiple stenoses - the "chain of lakes" appearance. Single smooth stenosis is also more consistent with chronic pancreatitis.⁴ The yield of biopsy in pancreatic cancer is >90% in most large series. Nearly all pancreatic malignancies are ductal carcinomas; thus even small lesions are likely to cause stenosis or occlusion of the main pancreatic duct. In cases where tumor invades the pancreatic duct region or ampulla without entering the lumen, cytology specimens of pancreatic juice may be diagnostic.

Limitations ERCP is relatively expensive and hazardous in comparison with other endoscopic procedures. Results are highly operator dependent, as demonstrated in large series. For both physician and patient there may be nontrivial radiation exposure if fluoroscopy time is prolonged. This procedure is technically difficult, particularly in patients who have had a Billroth II gastrectomy and gastrojejunostomy.

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