When is pancreatitis considered to be of biliary origin and what are the implications for management?

Acute pancreatitis is a disease caused by gallstones in 40-60% of patients. Identification of these patients is extremely important, since there are specific therapeutic interventions by endoscopic sphincterotomy and/or cholecystectomy. The combination of trans-abdominal ultrasound (stones in the gallbladder and/or main bile duct) and elevated serum alanine transaminase (circa >60 IU/l within 48 h of presentation) indicates gallstones as the cause in the majority of patients with acute pancreatitis. In the presence of a severe attack this is a strong indication for intervention by endoscopic sphincterotomy. The presence of a significant main bile duct dilatation is also strongly indicative of gallstones and should prompt the use of endoluminal ultrasonography: >8 mm diameter with gallbladder in situ, or >10 mm following cholecystectomy if aged <70 years and >12 mm, respectively, if > or = 70 years. In mild pancreatitis surgically fit patients should be treated by cholecystectomy, and intra-operative cholangiography, as pre-operative biliary imaging is not efficient in this setting. Patients who are not fit for cholecystectomy should undergo prophylactic endoscopic sphincterotomy to prevent further attacks. In the post-acute-phase, pancreatitis patients in whom the aetiology is uncertain should undergo endoluminal ultrasonography. Thisis the most sensitive method for the detection of cholelithiasis and choledocholithiasis and may reveal alternative aetiological factors such as a small ampullary or pancreatic cancer. A number of recent studies have shown that bile crystal analysis, a marker for microlithiasis, increases the yield of positive results over and above endoluminal ultrasonography, and should be considered as part of the modern investigative algorithm.