The passage of gallstones (macro- or microlithiasis) is theorized to play a role in inducing sphincter of Oddi dysfunction. This study examined the frequency at which biliary crystals are found in patients with suspected type II and type III sphincter of Oddi dysfunction.

A total of 85 patients (66 women, 19 men; mean age 38 years) with unexplained abdominal pain of suspected pancreatobiliary origin and no prior episode of pancreatitis underwent ERCP with sphincter of Oddi manometry and bile collection for crystal analysis. Eighty-one patients had a gallbladder in situ. No patient had evidence of stones or sludge on prior abdominal imaging. Sphincter of Oddi manometry was performed in standard retrograde fashion by using an aspirating catheter. Patients were classified by sphincter of Oddi dysfunction type by using a modified Hogan-Geenen classification system. Patients with type I sphincter of Oddi dysfunction were excluded. Bile was collected directly from the gallbladder (n=23) or common bile duct (n=62) after an infusion of 3.5 μg of cholecystokinin and was examined by light and polarizing microscopy for cholesterol crystals or calcium bilirubinate granules.

The proportion of patients with crystals was 3.5% (3/85). Thirty-five patients (41%) had elevated biliary and/or pancreatic sphincter pressure (type II, 16; type III, 19), of whom one (3%) had cholesterol crystals. Fifty patients had normal sphincter pressure, of whom two (4%) had cholesterol crystals (p=0.6). All 3 patients with cholesterol crystals had a gallbladder in situ. Calcium bilirubinate granules were not found in any patient.

Microlithiasis appears to be rare in patients suspected to have type II or type III sphincter of Oddi dysfunction. Evaluation of bile for crystals appears unproductive in this group of patients.