—NORMAL ANATOMY: Anomalies are so common in the biliary tract that this sketch illustrates a composite of conditions most commonly observed.
—ANOMALY: Unusually mobile common duct covered with filmy adhesions (very common). DANGER: If the surgeon is careless and in a hurry, he may clamp the common duct and obstruct it with the ligature, as shown in the insert.
—ANOMALY: The right hepatic artery proceeds anteriorly from its position under the common duct, coursing forward adjacent to the cystic duct, and enters the liver a few millimeters anteriorly; thus it may resemble the cystic artery (10% to 15% of cases). DANGER: If the surgeon does not recognize this anomaly, he may ligate the right hepatic artery, thinking it is the cystic artery.
—ANOMALY: The right hepatic artery crosses anterior to the common duct (present in about 16% of cases). DANGER: If the