This patient most likely has a retained stone in the common bile duct (CBD) that escaped the gallbladder prior to surgery but had not passed into the duodenum. The rise in bilirubin and transaminases are consistent with CBD obstruction. Postoperative infection would not cause jaundice and would be associated with fever. A bile leak would not cause such a high elevation of AST. The patient has a normal lipase level, effectively ruling out pancreatitis. A postoperative ileus is not associated with jaundice or a significant elevation of AST.