Bile duct diverticula and webs: nonspecific cholangiographic features of primary sclerosing cholangitis.

Biliary tree diverticula and webs are considered by several authors to be specific cholangiographic features of primary sclerosing cholangitis (PSC). Our experience suggested that these findings can be seen in patients without PSC. The purpose of this study was twofold: to establish whether diverticula and webs are indeed specific for PSC and to assess whether PSC can be accurately diagnosed without reference to diverticula or webs. We retrospectively reviewed 861 consecutive ERCP studies and found 32 cases of webs and/or diverticula. Using accepted cholangiographic, clinical, and histologic criteria, we diagnosed PSC in nine patients and excluded it in 21, with two instances of uncertain diagnoses. Webs and diverticula seen in PSC were cholangiographically indistinguishable from those in the group without PSC. All 21 patients without PSC had other biliary abnormalities, and were grouped by the predominant abnormality or finding believed to be associated with diverticulum or web formation: common duct stones or cholangitis (n = 11 patients), postoperative stricture (n = 4), bile duct stent and balloon dilatation (n = 3), malignant stricture (n = 2), and choledochoduodenostomy (n = 1). To assess cholangiographic diagnosis of PSC in these patients, a blinded reviewer studied the radiographs of the 30 patients with diverticula and/or webs who had confirmed diagnoses. By using established radiologic criteria alone (ignoring diverticula and webs), the correct diagnosis was made in 27, yielding a sensitivity of 89% and specificity of 91%. We conclude that the presence of diverticula and/or webs on a cholangiogram is a nonspecific finding and may be due to inflammation or trauma to the bile duct wall. Further, PSC can be distinguished from other abnormalities on the basis of findings other than diverticula and webs.