Congenital absence of the common bile duct: A rare anomaly of extrahepatic biliary tract.

Congenital absence of the common bile duct (CBD) is an extremely rare developmental anomaly with right and left hepatic ducts draining directly into the gallbladder (GB). Other synonyms for this clinical condition are "cholecystohepatic ducts", "transverse lie of the GB" or "interposition of the GB". The potential for iatrogenic injury is high, because of either inadvertent division or ligation of the ducts. Diagnosis is mostly made intraoperatively, and needs some form of biliary reconstruction. Herein, we are reporting a case of congenital absence of the CBD in a 36-year-old lady that was detected intraoperatively.

INTRODUCTION

The reported incidence of congenital extrahepatic biliary anomalies ranges from 0.58-47.2%.[1] The aberrant anatomy has been reported in up to 17% of cases with bile duct injury.[2] One such rare anomaly is congenital absence of the common bile duct (CBD). In our case, the CBD was absent and the common hepatic duct (CHD) was opening into the gallbladder (GB) through which bile was draining into the duodenum through the cystic duct (CD).

CASE REPORT

A 36-year-old lady was presented to us with symptoms of abdominal pain; ultrasonography (USG) of the upper abdomen suggested cholelithiasis and the CBD was reported as normal. Preoperative investigations including liver function tests were within normal limits. We proceeded with laparoscopic cholecystectomy via 4-port technique. The GB was thin-walled, distended and the CD appeared mildly dilated. Dissection was performed posterior to the CD and the CBD could not be seen in the porta. In view of the unclear structural anatomy, we started mobilizing the GB by fundus-first method. During dissection, the clear bile started draining from the liver bed. At this stage, laparoscopic surgery was terminated and converted to open, and it was found that a duct was opening into the GB wall through the bed and no CBD was present. Intraoperative cholangiogram was performed through the ductal opening in the GB fossa that revealed both right and left biliary ductal systems; the anomaly was confirmed as congenital absence of the CBD, with bile draining into the GB through the CHD and GB draining into the duodenum by the CD. Cholecystectomy was performed and Roux-en-Y hepaticojejunostomy (HJ) was performed with CHD [Figure 1]. Postoperative course of the patient was uneventful, and she was discharged on the 4th postoperative day. The histopathology of resected GB revealed chronic cholecystitis.

Figure 1

Pictorial description depicting intraoperative gallbladder anatomy, cholangiogram and Roux-en-Y hepaticojejunostomy

DISCUSSION

Congenital absence of the CBD is a rare anomaly of the extrahepatic biliary tract with right and left biliary radicals directly opening into the GB. In this situation, CD is the sole pathway for the biliary drainage. The possible explanation for this condition could be the presence of persistent connections between the foetal hepatic ducts and the GB with failure of complete recanalization of the extrahepatic biliary tract. Four variants have been proposed in literature[3] [Figure 2].

Figure 2

Variants of interposition of the gallbladder

The differential diagnosis for this clinical condition could be Mirizzi's syndrome type III/IV and Choledochal cyst. Mirizzi's syndrome can be distinguished by the presence of signs of inflammation in the Calot's and the presence of large impacted stone in the GB neck. Awareness of this anomaly and performing cholangiogram at the slightest suspicion are the possible intraoperative methods of the diagnosis.

If detected intraoperatively, GB resection with Roux-en-Y HJ (most preferred), partial cholecystectomy with closure of residual GB over T-tube (cholecysto-choledochoplasty)[4] or end-to-end CHD–CD anastomosis could be the management options. Cholecysto-choledochoplasty could be a preferred option in type III B but there is always a risk of recurrent stone formation in the residual GB leading to biliary obstruction and end-to-end CHD–CD anastomosis can lead to a high incidence of strictures. If the diagnosis is known preoperatively, cholecystojejunostomy can be a possible option as well.

Financial Support and Sponsorship

Nil.

Conflicts of Interest

There are no conflicts of interest.