Laparoscopic cholecystectomy is a well-established surgical procedure, and strategies to prevent BDI have been well-determined [3]. Although the critical view of safety is globally accepted as a standardized concept [4], the current cystic duct anomalies require exceptional strategies to prevent BDIs. In this case, a rare RHD anomaly entering the cystic duct was confirmed preoperatively, and the patient was successfully treated with endoscopic surgery using an ENBD that was preoperatively placed as a biliary guide. CT images during the first presentation showed a dilated RHD and a distended gall bladder. This finding implies the possibility of cystic duct anomalies that combined the right biliary branch draining together into the common hepatic duct (CHD), unless the gallbladder compressed the RHD, which is diagnosed as Mirrizi syndrome.
A well-known anomalous cystic duct requiring attention to prevent BDI during a laparoscopic cholecystectomy is characterized by the combination of the right posterior segmental duct (RPSD) draining into the CHD and cystic duct entering into RPSD. A previous investigation of cholangiograms on donors revealed that the rarity of RPSD draining directly into CHD was 6%, of which the anomalous posterior branch is close to cystic duct based on the anatomical positioning. Conversely, the rarity of RPSD or RHD entering cystic duct, as in the current case, is 2% or < 1%, respectively [5]. The real percentage of the cystic duct anomaly, as in the current case, is unclear due to its high rarity. Ten cases have been reported till date to be similar to the current case showing RHD entering cystic duct [2]. Intriguingly, one out of four cases (25%) showed RHD entering the proximal side of the cystic duct, causing a wide range of safe cut lengths of the cystic duct, implying that critical complications are less likely to occur intraoperatively. In contrast, three out of four cases (75%) showed RHD entering the distal side of the cystic duct, causing a very short range of safe cut length of the cystic duct, implying that unintended division of the bile flow in RHD is likely to occur intraoperatively (Fig. 4). In such cases, cutting cystic duct purposing to insert a catheter for intraoperative cholangiogram may cause serious complications even under laparotomy, because the cystic duct almost functions as the RHD and cannot be cut. Therefore, these cases, including our case, required subtotal cholecystectomy. Among the ten cases of anomalous RHD on the cystic duct, laparoscopic surgery was successfully performed in four [6,7,8]. The anomaly was confirmed by cholangiography using the percutaneous transhepatic gallbladder drainage catheter in two cases. Details of the intraoperative cholangiography procedure were not available in the other two reports. Based on these observations, intraoperative cholangiography should be carefully performed depending on the confluence position of the RHD on the cystic duct. We successfully performed laparoscopic cholecystectomy using an ENBD catheter placed during ERCP, which was aimed to diagnose an anomalous cystic duct preoperatively. This strategy decreases stress levels and prevents performance of technically difficult procedures intraoperatively [9].