Case report of a duplicated cystic duct: A unique challenge for the laparoscopic surgeon

Highlights • Double cystic ducts with a single gallbladder is exceedingly rare.• Diagnosis of this anatomic variant is most commonly made intraoperatively.• Knowledge of biliary aberancies is crucial to preventing bile duct injury.• IOC should be utilized to elucidate biliary anatomy when unclear.


Introduction
Biliary tree anomalies have been detected in up to 47% of the population based on operative, cholangiographic and autopsy studies [1]. The basis of bile duct injury is failure to identify biliary anatomy especially in the cases aberrancies. Thus, Identification of these anomalies in biliary anatomy is crucial to avoid the morbidity and mortality associated with bile duct injuries. Unlike the more common variant in which two cystic ducts drain two distinct gallbladders or cavities [2], duplicated cystic ducts draining a single, unilocular gallbladder is extraordinarily rare, with fewer than 20 cases reported in the English literature. We report our experience with laparoscopic cholecystectomy in the setting of double cystic ducts identified intraoperatively. The case report has been reported in line with the surgical case report (SCARE) criteria [3].

Presentation of case
We report a case of a 34-year-old female who presented to the emergency department with three days of constant right upper quadrant and epigastric abdominal pain with associated nausea. The patient had similar pain two months ago that resolved and did not seek medical attention. On presentation she had normal vital signs. Physical examination demonstrated right upper quadrant tenderness without peritoneal signs with negative clinical Murphy's sign. Her blood work revealed a white blood cell count of 13,500 /microliter, alanine aminotransferase of 318 U/L, aspartate aminotransferase of 259 U/L, alkaline phosphatase of 120 U/L, and total bilirubin of 1.7 mg/dL. Ultrasonography demonstrated new mild gallbladder wall thickening and negative sonographic Murphy's sign with equivocal suggestions of acute cholecystitis. Hepatobiliary iminodiacetic acid scan was subsequently performed and showed non-visualization of the gallbladder consistent with acute cholecystitis.
The patient was taken to the operating room and the cystic duct and artery were dissected free from the cystic triangle laparoscopically. Both structures were secured proximally and distally and divided sharply. The gallbladder was dissected from the bed using electrocautery. Due to the contracted and intrahepatic nature of   the gallbladder, approach was switched to a top-down technique. Just prior to removal of the gallbladder from the liver bed, another structure entering the gallbladder was encountered ( Fig. 1). At this point due to abnormal anatomy and inadequate visualization, the decision was made to convert to an open procedure. On further evaluation, the structure appeared to be a bile duct. Intraopera-tive cholangiogram was performed through the cystic duct that had been clipped earlier, which showed correct ductal anatomy with intact CBD, common hepatic, as well as right and left hepatic ducts (Fig. 2). An attempt was made to cannulate the second duct for cholangiogram and bile return was noted from the duct. How-ever, during cholangiography contrast extravasated outside rather than filling the bile duct, due to impacted stones blocking proximal aspect of the duct (Fig. 3). The second accessory duct was clipped and transected and the gallbladder was removed. The gallbladder was evaluated and showed the two cystic ducts with distal open lumens that communicated to the gallbladder. Postoperatively, the patient's liver function tests normalized. Patient was discharged home on postoperative day 3 and was tolerating diet. She was seen in the surgical clinic 2 weeks postoperatively and was doing well. The pathology report showed acute on chronic cholecystitis with mucosal ulceration and cholelithiasis.

Discussion
Intrigue with anomalous gallbladder anatomy and associated extrahepatic biliary duct aberrancy originates as far back as 1926 with Edward Boyden's comparative report and classification of the various congenital anomalies of the gallbladder [4]. Thirty years later, Caster and Flannery categorized cystic duct duplication into 3 types: (1)Ÿẗype, wherein 2 cystic ducts join to form a single cystic duct that then enters the CBD, (2)Ḧẗype, in which each cystic duct independently joins the bile duct system at the CBD, right hepatic duct, left hepatic duct or common hepatic duct, and (3) trabecular type, in which one cystic duct enters the CBD while the other directly enters the liver parenchyma [5].
Double cystic duct was identified intraoperatively in 16 out of the 19 patients (84%) who were operated on. Despite the completion of a preoperative endoscopic retrograde cholangiopancreatography (ERCP) in 7 patients, the cystic duct anomaly was only identified in 3 cases (43%) [1,2,[8][9][10]12,20]. This emphasizes the importance of being aware of this anatomic variant as even with invasive preoperative testing, the accessory duct was only identified intraoperatively. Cholecystectomy was performed and completed laparoscopically in 12 cases and intraoperative cholangiogram (IOC) was performed in 8 of these cases to delineate the anatomy when a second cystic duct was encountered [8][9][10][11][12]14,[16][17][18][19][20][21]. Three other cases required conversion to laparotomy, one of which was our case, and was due to inability to clearly define biliary anatomy laparoscopically [2,13]. One case required reoperative laparotomy due to delayed recognition of the duplicated cystic duct, resulting in bile leak [9]. An IOC and preoperative ERCP was performed in that case but did not prevent the complication of a biliary leak.

Conclusion
The limited success of preoperative biliary tract imaging in demonstrating anatomic aberrancies prior to cholecystectomy clearly highlights the importance of maintaining constant vigilance for even the slightest anatomic abnormality at operation. Any uncertainty or concern for ductal injury mandates immediate operative cholangiogram with cannulation of all structures in question. Although laparoscopic cholecystectomy is safe in experienced hands, a low threshold for conversion to laparotomy should be had when the anatomy cannot be deciphered.

Conflicts of interest
No conflicts of interest to be declared.

Funding
No source to be stated.

Ethical approval
The study is exempt from ethical approval in our institution.

Consent
Written informed consent was obtained for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.