Dynamic changes of common bile duct diameter during an episode of biliary colic, documented by ultrasonography

Common bile duct stones frequently accompany gallstones and can be identified by a variety of imaging modalities. Little is known about the time course of dilatation of the common bile duct after acute obstruction or of normalization after spontaneous passage of an obstructing stone. We describe a case showing rapid fluctuations in common bile duct diameter during 72 hours in a patient presenting with epigastric pain and vomiting. Initial emergency bedside ultrasonography revealed a distended gallbladder, a dilated common bile duct (17 mm), and an obstructing stone. Five hours later, ultrasonography performed in the radiology suite showed a normal common bile duct diameter (4 mm) and no obstructing stone. The patient was admitted, and during the course of hospitalization different imaging modalities reported fluctuations in common bile duct measurements, ranging from 4 mm on computed tomography to 14 mm on endoscopic retrograde cholangiopancreatography. This case demonstrates disappearance of an obstructing stone with normalization of a highly distended common bile duct during 5 hours, highlighting that gallstone disease may be highly dynamic, with the possibility of rapid changes of common bile duct diameter. Emergency physicians, who frequently depend on ultrasonography to diagnose biliary disease, should be wary of the potential for rapid changes of sonographic findings in these patients.