CHD was first reported by Neuhof et al. [1] in 1945 as an anomaly that caused the hepatic ducts to drain a certain area of the liver into the gallbladder. Some authors use the term of “Cystohepatic duct” for this anomaly [4], but the cystohepatic duct is defined as those draining variable portion of the right lobe into the cystic duct [5]. Thus, CHD is considered as optimal terminology for this case. CHD is thought to arise as a result of abnormal biliary tract embryology, and its incidence is much lower than that of other aberrant hepatic ducts. A large case series based on operative and cholangiographic findings demonstrated an overall incidence of CHD as 0.07% (only 1 case in a total of 1410 cholecystectomies) [4, 5].
As a cause of bile duct injury during cholecystectomy, anatomical anomalies of the bile duct are common, as well as a surgical difficulty due to severe inflammation and adhesion. Anomalous drainage of the right posterior hepatic duct joining into the common hepatic duct is the most frequent cause of bile duct injury [6,7,8,9]. However, several cases of bile duct injury have been reported in CHD [10,11,12,13]. In all these cases, CHD was not recognized either pre- or intraoperatively, but was confirmed postoperatively because of bile leakage. Thus, preoperative detection of CHD seems to be difficult but important for avoiding a bile duct injury. We routinely perform MRCP or DIC-CT before cholecystectomy to evaluate biliary anomaly. MRCP is preferable to avoid radiation exposure but it is difficult to perform rapidly unless emergency in our hospital. Thus, we often perform DIC-CT as in this case. In the present case, the preoperative DIC-CT revealed the CHD as a small bile duct branch with no communication between intra- and extrabiliary systems. However, it was missed due to a lack of awareness of the surgeons. If we had been experienced such a case before, we might be noticed it. Therefore, we consider that the most important tips to detect a CHD is to recognize and suspect its existence. When a bile duct branch with unclear confluence near the gallbladder was described by preoperative image, we should suspect it as a CHD.
To avoid bile duct injury, as well as preoperative detection of bile duct anomalies, safety surgical procedure is extremely important. The critical view of safety has been established as a safety procedure of laparoscopic cholecystectomy [14], and also the dissection by exposing the inner layer of the subserosal layer has been known as an effective surgical procedure [15]. However, differ from the aberrant hepatic ducts joining into the extrahepatic bile duct, even if CHD was detected before surgery and safety surgical procedures were completely performed, it must be divided in order to resect the gallbladder. Three surgical options are available for managing CHD that is detected before or during cholecystectomy. First, in case the drainage area of CHD is large, biliary reconstruction is necessary. Kurata et al. [16] reported reconstruction of posterior sectional bile duct using Roux-en-Y choledochojejunostomy and Hamada et al. [17] described an anastomosis of the anterior inferior segmental bile duct to the remnant cystic duct. Secondly, if the drainage area of CHD is small, closure of CHD is permissible. As the initial management of a bile duct injury, Longmire et al. [18] described the ligation of small segmental ducts (i.e., < 1 mm), and recommended bile duct reconstruction for ducts with a diameter of ≥ 2 mm. In our presenting case, the CHD was rather thin with a drainage area comprising only a part of the right posterior inferior segment. Therefore, we considered that biliary reconstruction was unnecessary. No clinical problems were observed over 4 years following the surgery. However, dilatation of the ligated CHD remains without liver atrophy, requiring a long-term follow-up, focused on the elevation of liver enzymes and the occurrence of obstructive cholangitis. Thirdly, the remaining surgical option is CHD preservation. In cases where the CHD connects to the cystic duct (i.e., cystohepatic duct) or the neck of the gallbladder, it is possible to preserve it through gallbladder dissection on the right side of the CHD confluence (i.e., subtotal cholecystectomy). Kurata et al. [16] and Hirai et al. [19] reported the case of subtotal cholecystectomy, preserving the CHD or cystohepatic duct.
When the CHD was noticed after surgery by bile leakage from the drain or bile peritonitis, strategy for the management of resected CHD had not been established. Rathore et al. [11] experienced a case of bile leakage from the drain on a postoperative day 1. The CHD injury was confirmed by drainage tubography on postoperative day 11 and the bile leakage stopped 27 days after the operation. Uemura et al. [13] reported that bile leakage from the resected posterior sectional bile duct improved following percutaneous abdominal drainage, without percutaneous transhepatic biliary drainage or reoperation. However, Zrin et al. [20] performed a reoperation and ligated the CHD for bile peritonitis.
