Duplicated common bile duct: a recipe for biliary injury. Report of a new variant

A 64-year-old female presented to the surgical emergency unit with a day's history of right upper quadrant pain. Her physical examination revealed right upper quadrant tenderness with no rebound tenderness or muscular guarding. Other systemic findings were normal. Laboratory test showed leukocytosis of 17 × 10³/µL and elevated C-reactive protein of 51 mg/L (0–5 ml/L). Other laboratory values including serum amylase, bilirubin and transaminases were normal. Abdominal ultrasound revealed thickened gallbladder (GB) wall (4.7 mm) with a 25 mm gallstone. A diagnosis of acute calculous cholecystitis was made and intravenous fluid and antibiotic treatment were initiated. Laparoscopic cholecystectomy was considered after 48 h of observation. During surgery a standard 4-port technique was used after pneumoperitoneum using the Veress needle. GB wall was found to be inflamed with omental adhesions. Using the critical view of safety approach, the cystic artery and cystic duct were separately identified, clipped and transected. After careful dissection of the GB from the liver bed small amount of bile was observed oozing from a spot proximal to the ligated cystic duct stump. Irrigation of the spot revealed a small tear at what was thought to be the common hepatic duct. A 5-Fr drainage catheter (50 cm long, 1.4 mm in diameter) was placed into the opened duct and exteriorized through the mid-clavicular 5 mm port site for post-operative drainage. A tube cholangiography done on post-operative Day 7 showed duplication of the common hepatic duct proximal to the cystic duct stump with the injury occurring on the right-sided duct (Fig. 1). A magnetic resonance cholangiopancreatography (MRCP) was taken which confirmed the presence of the duplicated common hepatic duct with the cystic duct stump distal to the duplication (Fig. 2). No PBM was observed. Her post-operative course was uneventful with an average biliary drainage output of about 300 ml. Drainage tube was clamped on post-operative Day 9 and finally removed 4 weeks after surgery. No complication was observed and patient is currently doing well.

The wide variation in morphology of reported cases of DCBD has posed a great challenge in its precise anatomical definition and classification. Goor and Ebert initial classification described seven configurations divided into four groups [2]. Choi et al. proposed modified classification system describes five groups, with subtypes, involving seven variants as depicted in Fig. 3 [4]. In the case presented here-in, the anomaly was discovered post-operatively by tube cholangiography following iatrogenic bile duct injury during laparoscopic cholecystectomy. The double ducts were noted to originate from the hepatic duct confluence separately and rejoined distally with the cystic duct noted to open into the unified duct (Figs 1 and 2). The injury occurred on the right-sided duct. This variant appears to be different from previously reported type V in which the cystic duct opens into the right duct before joining the left duct. Therefore this case appears to be a new variant not previously reported or classified. Literature review showed similar reported cases of inadvertent BDI associated with DBCD during surgery [6, 7] and other configurations that could not be classified with existing classification systems [3, 5, 8] [Fig. 4]. These reports reaffirm and underscore the importance of prior knowledge of the existence of this anomaly and careful dissection within the hepato-gastroduodenal ligament to avoid BDI, particularly during laparoscopic cholecystectomy. The clinical importance of this anomaly lies with its association with conditions such as cholecysto-choledocholithiasis and choledochal cyst, the risk of malignant transformation and the risk of exposing patients to biliary injury during surgery, if not detected pre-operatively. The type of malignant transformation seems to be directly related to the drainage site of the ducts (gastric, duodenal or pancreatic) and the presence of PBM [1]. In a review of 47 cases in the Japanese literature, Yamashita et al. reported an incidence of cholelithiasis in 28%, choledochal cyst in 11%, PBM in 30% and malignancy in 26% of the cases [1]. An earlier review by Kanematsu et al. [9] reported an incidence of 48% calculous formation associated with DCBD anomaly. Review of 24 cases in the Chinese literature also revealed cholelithiasis in 37%, choledocholithiasis in 79%, choledochal cyst in 33% and PBM in 8% of the reported cases [10]. The high incidence of gallstone formation associated with this anomaly is thought be due to bile stasis and repetitive cholangitis resulting from reflux of gastrointestinal content into the anomalous duct.