Is Biliary Microlithiasis a Significant Cause of Idiopathic Recurrent Acute Pancreatitis? A Long-term Follow-up Study

Background & Aims: The cause of recurrent acute pancreatitis (RAP) is not known in 10%-30% of patients. The aim of the present study was to determine the cause of idiopathic RAP in a long-term follow-up study. Methods: All consecutive patients with idiopathic RAP underwent detailed evaluations and investigations to find out the cause. The pancreatitis was considered to be idiopathic when no cause could be found after standard investigations that included serum biochemistry, transabdominal ultrasonography, and computerized tomography scan of the abdomen. The detailed work-up included repeat serum biochemistry and transabdominal ultrasonography, an endoscopic retrograde cholangiopancreatography, duodenal bile microscopy to diagnose biliary microlithiasis, and endoscopic ultrasonography. Results: Seventy-five patients were studied from June 1995 to May 2003. Their mean age was 31.9 years and 80% were male. The mean number of attacks of acute pancreatitis was 4.82 (range, 2-10). The cause of RAP was attributed to biliary microlithiasis in only 10 (13%) of 75 patients. Two additional patients developed gallstones during the follow-up period. Thirty-five (47%) patients developed chronic pancreatitis during the follow-up period. Ten of these 35 patients with chronic pancreatitis had biliary microlithiasis; 8 of these 10 patients had undergone cholecystectomy/endoscopic sphincterotomy yet continued to have recurrent pancreatitis and developed chronic pancreatitis. Miscellaneous causes were found in 10 (13%) patients. No cause was found in the remaining 18 (24%) patients. Conclusions: Microlithiasis was not a significant cause of idiopathic RAP in our patients. About one half of the patients with RAP developed chronic pancreatitis during the follow-up period.