Endoscopic therapy of recurrent acute pancreatitis
ABSTRACTEndoscopic therapy has emerged as an alternative to surgery for the subset of patients with acute recurrent pancreatitis whose disease is due to gallstones or other mechanical processes that obstruct the outflow of the pancreas. In this article, the authors review the specific situations in which endoscopic therapy might be useful in patients with acute recurrent pancreatitis.
KEY POINTS
- Recurrent attacks of acute pancreatitis can be prevented only by determining and treating the underlying cause.
- Endoscopic procedures can cause anxiety and carry a risk of bleeding, perforation, and pancreatitis. The risks, benefits, and other treatment options should be discussed with the patient.
- Endoscopic therapy is now the preferred treatment of sphincter of Oddi dysfunction at centers that have experience with this technique.
- In patients with pancreas divisum and recurrent acute pancreatitis, surgical and endoscopic minor sphincterotomy are equally effective.
STONES AFTER CHOLECYSTECTOMY
Bile duct stones can be classified as primary or secondary. A primary stone is one that remains where it was formed, whereas a secondary stone is one that has migrated from its site of formation.21
Some suggest that bile duct stones that are detected within 2 years of cholecystectomy originated in the gallbladder and were missed when the gallbladder was removed (and therefore are considered secondary stones), and that stones that present more than 2 years after cholecystectomy are de novo (ie, primary) stones.22,23
In any event, stones have been found in the common bile duct in 4% to 24% of patients up to 15 years after cholecystectomy.24–26 A fair number of these patients have no symptoms.27 Risk factors for stone recurrence are lithogenic bile (ie, high concentration of cholesterol, low concentration of bile salts), biliary stasis, strictures, dilated bile ducts, and advanced age.28–30
No role for crystal analysis after cholecystectomy
Biliary crystal analysis does not seem to have diagnostic value in patients with recurrent acute pancreatitis after cholecystectomy,31 because removing the gallbladder eliminates the crystals and sludge. Imaging studies are therefore the cornerstone of diagnosis.
Transabdominal ultrasonography is the most commonly used initial imaging test. However, abdominal fat and gas in the duodenum can obscure the distal common bile duct and decrease the sensitivity of this test.32
Endoscopic ultrasonography involves positioning the transducer in the second part of the duodenum, where it can show the adjacent biliary tree without interference from digestive gas or abdominal fat.
Magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasonography are both highly sensitive for detecting common bile duct stones and are recommended if they can be done without delay.
Endoscopic retrograde cholangiopancreatography (ERCP). As a rule, patients who are very likely to have gallstones are best served by proceeding directly to ERCP, a procedure that enables both imaging and treatment. However, ERCP exposes the patient to radiation and the risk of pancreatitis, so in some patients (eg, pregnant women, people who recently had acute pancreatitis), one may want to do ultrasonography first.
ERCP is the treatment of choice after cholecystectomy
The treatment of choice in patients with choledocholithiasis is ERCP with biliary sphincterotomy and stone extraction. Success at clearing the biliary tree of all stones depends on the size, number, and location of the stones, the anatomy of the digestive tract and the bile duct, and the experience of the endoscopist. At specialized centers, the rate of successful clearance with subsequent procedures is close to 100%. Large stones may require fragmentation inside the bile duct to aid their removal.33
SPHINCTER OF ODDI DYSFUNCTION
The sphincter of Oddi, located where the bile and pancreatic ducts penetrate the wall of the duodenum, actually consists of three sphincters: the common, the biliary, and the pancreatic. Its physiologic role is to regulate the flow of bile and pancreatic juice into the duodenum and to prevent reflux into the ducts from the duodenum.34 Its basal pressure is the main regulating mechanism for pancreatic and biliary secretions into the intestine, and its phasic contractile activity is closely associated with duodenal motility.
Sphincter dysfunction: Stenosis, dyskinesia
The sphincter of Oddi can obstruct the flow of bile and pancreatic juice owing either to stenosis or to dyskinesia.35,36 Stenosis refers to structural alteration of the sphincter, probably from inflammation and subsequent fibrosis. In contrast, dyskinesia refers to a motor abnormality of the sphincter that makes it hypertonic.
Stenosis or dyskinesia can occur in the biliary sphincter, the pancreatic sphincter, the common sphincter, or any combination of the three. For example, dysfunction of the biliary sphincter can cause abnormalities in liver-associated enzyme levels and biliary-type pain, whereas pancreatic sphincter dysfunction can cause recurrent attacks of pancreatitis and pancreatic-type pain.37 Elevated pancreatic sphincter pressure has been shown to correlate with increased pancreatic ductal pressure, suggesting that the sphincter plays a role in the pathogenesis of acute pancreatitis.23,38
Sphincter pressure can be measured during ERCP, but ERCP is risky
The gold standard for the diagnosis of sphincter of Oddi dysfunction is manometry,23,35 ie, direct measurement of sphincter pressure via a thin catheter placed inside the pancreatic or biliary sphincter during ERCP (Figure 1).
However, in patients with suspected sphincter of Oddi dysfunction, ERCP with or without manometry is associated with a high rate of complications, with pancreatitis occurring in up to 25% of cases.39–41 Therefore, several noninvasive and provocative tests have been designed in an attempt to identify patients with this disorder. Unfortunately, none of them seems to be as sensitive and specific as manometry for diagnosing sphincter of Oddi dysfunction, and so they have not gained widespread use.
Opening the sphincter of Oddi with drugs, endoscopy, or surgery
Drug treatment of sphincter of Oddi dysfunction is based on drugs that relax smooth muscle, such as calcium channel blockers and nitrates. The treatment must be lifelong. Also, it does not improve sphincter stenosis, and only half of patients with sphincter dyskinesia respond to it. For these reasons, drug treatment of sphincter of Oddi dysfunction has not gained widespread acceptance.36,42
Endoscopic sphincterotomy is the current standard endoscopic therapy for sphincter of Oddi dysfunction. This procedure is performed during ERCP and involves cutting the sphincter with electrocautery.
Endoscopic pancreatic sphincterotomy prevents recurrent attacks of pancreatitis in patients with pancreatic sphincter dysfunction in more than 60% of cases.23,43–46 A potential complication is pancreatitis, which occurs more often in patients with pancreatic sphincter dyskinesia. Placing a stent in the pancreatic duct after pancreatic sphincterotomy reduces the risk of pancreatitis after ERCP.37,47,48
Surgery. Pancreatic sphincterotomy can also be done surgically, most commonly via transduodenal pancreatic sphincteroplasty. Surgical sphincteroplasty is as effective as endoscopic sphincterotomy for preventing recurrent attacks of pancreatitis in patients with pancreatic sphincter dysfunction.49 However, endoscopic therapy is much less invasive and remains the preferred treatment for sphincter of Oddi dysfunction in most centers with experience in this technique.50
