Endoscopic Retrograde Cholangiopancreatography

Anatomy and Physiology

The main pancreatic duct connects to the common bile duct and drains at the ampulla of Vater (hepato-pancreatic ampulla), controlled by the sphincter of Oddi. The major duodenal papilla is the opening of the ampulla of Vater into the second part of the duodenum. The common bile duct and the pancreatic duct may remain separate or merge at the end of the papilla, or they may form a common duct.

In 10% of the population, a normal anatomic variant happens, called pancreas divisum, where the major pancreatic duct (duct of Wirsung) and the lesser pancreatic duct (duct of Santorini) do not fuse, and the minor duodenal papilla would be the main way for drainage of the pancreas. The minor duodenal papilla is about 2 cm proximal to the ampulla of Vater and may have a sphincter, known as the sphincter of Helly.

Indications

ERCP uses endoscopy to find the major and minor papillae. Cannulation is done, and contrast material is injected to identify the biliary and pancreatic ductal systems. During ERCP, diagnostic procedures can be done, namely cholangiopancreatoscopy, biopsy, or brush cytology. An intraductal ultrasound may also be done. Therapeutic uses include sphincterotomy, stent placement, and stone removal.[4][5][6]

ERCP indications include obstructive jaundice, biliary or pancreatic ductal system disease treatment or tissue sampling, suspicion for pancreatic cancer, pancreatitis of unknown cause, manometry for sphincter of Oddi, nasobiliary drainage, biliary stenting for strictures and leakage, drainage of pancreatic pseudocysts, and balloon dilation of the duodenal papilla and ductal strictures. Sphincterotomy is indicated in cases of the sphincter of Oddi dysfunction or stenosis, difficulty with biliary stenting or accessing the pancreatic duct, biliary strictures, bile duct stones, bile sump syndrome following choledochoduodenostomy, choledochocele, and in poor surgical candidates with ampullary carcinoma.

Contraindications

ERCP is contraindicated when there is a lack of evidence for biliary or pancreatic disease, when safer diagnostic tools are available, in cases of abdominal pain of unknown cause, and when ERCP would not change the plan of action.[7][8][9]

Equipment

The side-viewing duodenoscope is considered the standard for ERCP procedure as it allows a better view of the major duodenal papilla, rendering cannulation easier. In patients with reconstructed gastrointestinal anatomy, as in patients with Billroth II gastrectomy or Roux-en-Y operation, the afferent loop entrance is hidden, and at a sharp angle, the afferent loop is elongated, and the papillary position is reversed. In these situations, the traditional side-viewing endoscope provides a limited visual field and makes afferent loop intubation challenging, thus increasing the risk for intestinal injuries. A forward-viewing endoscope may be a reasonable alternative in these circumstances, where afferent loop intubation would be easier, but papillary cannulation would be more challenging. The reversed papillary position makes it difficult for both side-viewing and forward-viewing endoscopes. The double-balloon enteroscopy technique uses two balloons to advance the forward-viewing endoscope through the intestine by alternating inflating and deflating balloons.

The dual lumen forward-viewing endoscope would allow the use of other surgical tools as an Allis forceps to hold the papilla, and using a stiffer endoscope with manual compression or instruments like polypectomy snare may be considered to make cannulation easier.

Personnel

One or 2 skilled endoscopists are needed for the procedure along with personnel for anesthesia.

Preparation

The American Society for Gastrointestinal Endoscopy (ASGE) issued a guideline for routine laboratory testing before endoscopic procedures. They recommend against routine radiographic, cardiac, or laboratory testing before endoscopy for otherwise healthy patients, but recommend selective testing based on patient's and procedure's risk factors. They recommend a pregnancy test when appropriate, hemoglobin/hematocrit, and blood typing and screening in patients with anemia, bleeding, or when blood loss is expected during the procedure. Coagulation studies are also indicated in patients with bleeding or bleeding disorders, biliary diseases, or poor nutrition. A chest radiograph is only indicated if the patient has respiratory or cardiac symptoms. Other laboratory testing should be ordered based on the patient's medical history. As with other procedures that require sedation, patients need to be fasting before the procedure.

Antibiotic prophylaxis is not routinely recommended prior to ERCP. However, it is recommended in patients with a liver transplant or biliary obstruction. Biliary flora, including enterococci and gram-negative organisms, should be covered, and antibiotics should be continued after ERCP if biliary drainage is incomplete.

Technique or Treatment

Techniques used in ERCP include endoscopic papillectomy, sphincter of Oddi manometry, sphincterotomy, endoscopic papillary balloon dilation, stone removal, tissue sampling, placement of biliary and pancreatic stents, cholangiopancreatoscopy, and biliary and pancreatic drainage. 

The procedure starts with passing the duodenoscope through a mouthguard. Duodenoscope is then advanced through stomach pylorus into the duodenal bulb. The scope should be advanced to the second part of the duodenum to visualize the major duodenal papilla, a protuberance at the junction of the horizontal and vertical duodenal folds. Cannulation of the major duodenal papilla is then done. The recommended wire-guided technique is done through a guidewire that passes under fluoroscopy into the common bile duct or pancreatic duct before contrast injection.

On the other hand, the standard contrast-assisted method involves contrast material injection after introducing the cannulation device tip into the major duodenal papillary orifice to assure proper positioning. Difficult cannulation may be due to periampullary diverticulum, impacted biliary stone, bile duct stenosis, or tumor of the bile duct or pancreatic head. Infrequently, cannulation of the minor papilla with sphincterotomy may be done in cases of idiopathic recurrent acute pancreatitis or patients with pancreas divisum.

Ways to perform per-oral cholangiopancreatoscopy include a mother-baby system (dual operator), SpyGlass technique (single operator), and direct per-oral cholangioscopy (DPOC).

Dual operator system, which is also known as a mother-baby system, requires two endoscopists to operate, where one endoscopist controls the mother duodenoscope, and the other endoscopist controls the baby cholangiopancreatoscope, with a tip that is deflectable in one plane which is up and down only.

Single operator SpyGlass technique, is catheter-based, where the optical probe is passed through a 4-lumen catheter, with a tip that is deflectable up-down and right-left.

In the dual operator and single operator techniques, the cholangioscope is passed through the 1.2 mm working channel of the therapeutic duodenoscope, over a guidewire into the biliary duct.

DPOC uses ultraslim and transnasal endoscopes, with digital imaging. They are used in cases of dilated common bile duct as their shaft diameters range from 4.9 to 5.9 mm. Insufflation in these situations should be done using water or carbon dioxide to prevent air embolism from happening.

Cholangioscopes’ distal diameters range from 3.1 to 3.5 mm. ERCPs working lengths range from 187 to 220 cm. Ultraslim endoscopes have a wide range of angulation, working length ranging from 65 to 110 cm, and working channel diameter ranging from 2 to 2.2 mm, allowing for accessories for cholangioscopy including biopsy forceps, electrohydraulic lithotripsy, and laser lithotripsy.

Complications

Complications directly attributed to ERCP are as high as 6.8%. A quarter of these are severe and most commonly require intervention, blood transfusion more than 4 units, or hospitalization over 10 days. Mortality rates are about 0.3%. The incidence of post-ERCP pancreatitis (PEP) is 3.5%, making it the most frequent complication following the procedure. In 90% of cases, pancreatitis is mild-to-moderate in severity. Infections, as cholangitis and cholecystitis, occur at a rate of 1.4%. Gastrointestinal (GI) bleeding happens 1.3% of the time. Although duodenal and biliary perforations occur at a lower rate of 0.6%, mostly related to sphincterotomy, they carry the highest mortality rates among ERCP complications.

Other complications account for 1.3% of total complications. These include cardiovascular and analgesia-related events, pneumothorax, retroperitoneal, mediastinal and subcutaneous emphysema, hepatic hematoma, portal venous air embolism, splenic injury, post-sphincterotomy papillary or ampullary restenosis, duodenal obstruction, and impaction of the basket catheter while removing biliary stones.

Definite risk factors that increase the incidence of PEP include increased cannulation attempts duration (more than 10 minutes and possibly more than 5 minutes), pancreatic guidewire passage more than once, pancreatic injection of high-osmolality contrast material, previous pancreatitis, suspected sphincter of Oddi dysfunction, and female gender. Likely risk factors include intraductal ultrasound, failure to remove bile duct stones, endoscopic papillary balloon dilation, and pancreatic sphincterotomy. Precut sphincterotomy is not a certain risk factor as increased PEP risk may be related to increased cannulation attempts associated with this procedure. Needle-knife fistulotomy is recommended to other precut techniques, as it carries fewer complications, including PEP. Other likely risk factors that are patient-related include previous PEP, younger age, absence of chronic pancreatitis, and normal serum bilirubin levels. Serum amylase levels obtained 2-6 hours post-ERCP are considered normal if less than 1.5 times the upper limit of normal. Similarly, serum lipase levels obtained at the same time are considered normal if less than 4 times the upper limit of normal. When indicated, endoscopic papillary balloon dilation should be longer than 1 minute.

Nonsteroid anti-inflammatory drugs (NSAIDs) decrease the incidence of PEP. Hence it is recommended that patients undergoing ERCP get routine rectal diclofenac or indomethacin immediately before or after the procedure. Aggressive hydration using lactated Ringer's solution help decrease the incidence of PEP. Sublingual nitroglycerin or bolus injection of 250 micrograms of somatostatin should be considered an alternative in high-risk patients, if NSAIDs are contraindicated and if prophylactic pancreatic stenting is not feasible. Topical epinephrine should not be used routinely. Other possibly effective drugs include somatostatin, octreotide, ceftazidime, and anti-protease drugs as nafamostat, gabexate, and ulinastatin. They are still not recommended for PEP. Drugs proven ineffective include drugs reducing sphincter of Oddi pressure other than nitroglycerin (lidocaine, nifedipine, and botulinum toxin), glucocorticoids and other anti-inflammatory drugs (recombinant platelet-activating factor acetylhydrolase, pentoxifylline, and semapimod), heparin, interleukin-10, and antioxidant drugs (N-acetylcysteine, natural beta-carotene, and allopurinol). Routine use of low-osmolality contrast materials is not recommended. The number of cannulation attempts and volume of contrast material injected should be as low as possible. Patient positioning does not affect the incidence of PEP. The use of carbon dioxide for insufflation decreases post-procedure abdominal pain and is therefore recommended. The wire-guided technique used for cannulation is recommended. European Society of Gastrointestinal Endoscopy (ESGE) recommends the use of short 5-Fr pancreatic stents rather than 3-Fr stents in high-risk patients, which would decrease the risk of severe PEP to almost nil. Retained stents should be removed within 10 days of placement. It is recommended that manometry for sphincter of Oddi be done using a modified triple-lumen perfusion catheter with immediate aspiration or a non-water-perfused micro transducer catheter.

Clinical Significance

Although ERCP initially started as a diagnostic procedure, it has evolved over the years to be a predominantly therapeutic tool. Given the invasiveness of the procedure, it does have a significant rate of complications.

Enhancing Healthcare Team Outcomes

ERCP is an invaluable technique for many bile duct disorders but healthcare workers including the nurse practitioner must be aware that this technique is also associated with high morbidity. Patients with cardiac risk factors should undergo preoperative screen to minimize these risks. An interprofessional team consisting of the endoscopist, gastroenterology nurse, and anesthesiologist can improve outcomes. [Level 5]

The outcomes for most patients are good and in some cases, life saving.[2][10][11]