Preoperative diagnosis of the Mirizzi syndrome: limitations of sonography and computed tomography.

Preoperative recognition of the Mirizzi syndrome permits avoidance of several serious pitfalls at surgery. The typical diagnostic signs of the Mirizzi syndrome are (1) dilatation of the common hepatic duct above the level of (2) a gallstone impacted in the cystic duct, with (3) normal duct width below the stone. Since jaundice is the leading clinical symptom, sonography and computed tomography (CT) are now the primary radiologic tests. The syndrome does not regularly have typical features, however, and therefore cannot be detected routinely on sonography or CT. Direct cholangiography is often necessary, especially since a cholecystobiliary fistula secondary to stone penetration into the common bile duct can be demonstrated only by cholangiography. On the other hand, direct cholangiography should follow either sonography or CT because these imaging methods are superior for demonstrating extraluminal signs of malignancy, which is the most important differential diagnosis. The findings at preoperative examinations (sonography, six; CT, four; endoscopic retrograde cholangiography, five) in seven patients with surgically confirmed Mirizzi syndrome are analyzed retrospectively.