Hepatobiliary and Pancreatic: Agenesis of the gallbladder

Abstract

Aman, aged 41, was seen in the Emergency Service because of the acute onset of pain in the right upper quadrant of the abdomen that was associated with nausea. He described similar episodes on two previous occasions. On examination of the abdomen, the only abnormality was mild tenderness on palpation over the right upper quadrant. Screening blood tests including liver function tests and serum amylase were within the reference range. His pain settled with analgesia and he was given an outpatient appointment for an upper abdominal ultrasound scan. The gallbladder was poorly seen but the possibility was raised of a contracted gallbladder with multiple stones. Because of continuing minor symptoms, he was advised to proceed with elective laparoscopic cholecystectomy.At operation, it was not possible to identify the gallbladder. The appearance of the gallbladder fossa is shown in Figure 1. Magnetic resonance cholangiopancreatography (MRCP) was performed after surgery and showed congenital absence of the cystic duct and gallbladder (Figure 2). An incidental finding was that of pancreas divisum. Agenesis of the gallbladder is a rare congenital anomaly with an estimated prevalence of between 1 and 10 per 10,000 people in the general population. The anomaly is usually sporadic although there are occasional reports of two affected members within families. Embryologically, the anomaly is presumed to arise because of a defect in the development of the gallbladder bud that arises from the caudal portion of the hepatic bud. Most patients do not have a cystic duct stump. At surgery, gallbladder agenesis should only be diagnosed after a careful search of ectopic locations, particularly an intrahepatic or left-sided gallbladder. Intraoperative cholangiography may also be helpful if the bile duct can be readily identified. However, extensive surgical dissection of the area should be avoided as this may result in injury to hilar structures. MRCP either before or after surgery may also be helpful in those patients with uncertain results from ultrasound or computed tomography scans. In the above patient, possible causes for pain include an atypical irritable bowel syndrome, a motility disorder of the sphincter of Oddi and perhaps pancreas divisum. There are also rare reports of agenesis of the gallbladder with primary bile duct stones.