Annular pancreas: etiology and diagnosis using endoscopic retrograde cholangiopancreatography.

A case of annular pancreas diagnosed by endoscopic retrograde cholangiopancreatography (ERCP) is described and the etiology of the abnormality considered. Annular pancreas is an anomaly of the ventral pancreas, and probably due to the persistence of the left ventral bud; the dorsal pancreas plays no apparent role in its development. In the diagnosis of annular pancreas, it appears that ERCP provides unequivocal evidence in some, quite possibly all, cases.