An accessory double cystic duct with single gallbladder

Introduction
As it is known the congenital abnormalities of the extrahepatic biliary duct system are possibly the most frequent variations of the human body. It is suggested that the normally found anatomy of the biliary tract is found in only 50% of the population (1). These variations achieve their significance given the fact that cholecystectomy is the most frequently performed surgical procedure.
Few of these variations are very rare and the surgeon should be aware of the presence of such variations. In the opposite case he should be confused damaging a possible existent aberrant biliary duct or searching a normal biliary duct in an ectopic location. One of the extremely rare abnormalities of the cystic duct is the duplication of the cystic duct with a single gallbladder. In he reported case there are two cystic ducts, the main duct branched from the common hepatic duct and the aberrant duct branched from either the common hepatic, or the right hepatic duct or an hepatic biliary ductile. The first case of cystic duct duplication was described by C. Steger in 1956 (2). Since then 14 cases have been reported (3). On of them was combined with common bile duct duplication (4). We report on a very rare case of double cystic duct with single gallbladder in a woman cadaver and emphasize the possible complications in case of the second cystic duct damage.

Case report
At the Department of Anatomy of our Medical School during routine dissection of cadavers we prepared the region of the extrahepatic biliary tract in order to study its macroscopic anatomy. To our surprise we found a double ductal system communicating the gallbladder with the common hepatic duct (Fig. 1). Specifically, the two cystic ducts formed with the common hepatic duct a triangular formation. Initially we confused the upper cystic duct with an aberrant hepatic duct connecting the neck of the gallbladder with the common hepatic duct. The upper cystic duct was measured in length 3,2 cm and was directed obliquely superiorly and medially, while the lower cystic duct (the primary duct) was longer (4,4 cm) and was directed medially and inferiorly terminating into the common hepatic duct at the level of superior border of ascending portion of the duodenum. In our case there was only one cystic artery originating from the right hepatic artery and accompanying the lower cystic duct (this artery has been resected in our case).

Discussion
As it has been reported the congenital abnormalities of the extrahepatic biliary ducts are not uncommon. The duplication of the cystic duct is one of the rarest variations of the biliary tract since there are only 14 such cases reported in the literature. The first description of that anomaly was made by Steger in 1956 (2), while the first report of double cystic duct found in laparoscopic cholecystectomy was made by Hirono et al in 1997 (5). According to Dia et al (6) the cystic duct duplication appears in one of the following types: i) The two cystic ducts arise separately from the gallbladder and unite in a single common cystic duct that terminates into the common hepatic duct (type "Y"). ii) The two cystic ducts arise separately from the gallbladder and terminate separately into the common hepatic duct (type "H"). iii)The second (accessory) cystic duct terminates into the right hepatic duct or in an intrahepatic duct (Fig. 2). There is also another type of variation in which an internal longitudinal diaphragm exists; that diaphragm separates the cystic duct in two parallel cystic ducts (6). That diaphragm should be distinguished from the vertical and oblique diaphragms that very rarely develop within the lumen of the cystic duct (7).
In respect to double cystic duct pathogenesis there are two theories. According to the first one an anomaly in recanalisation procedure of the extrahepatic biliary tree occurs resulting he formation of an alternative communication between gallbladder and common hepatic duct. According to the second theory the distal portion of the one bud of the gallbladder disappears, while the proximal one unites with the other bud of gallbladder as second cystic duct (8).
Stremple support that 85% of all variations in the hepatic pedicle are found in Moosman's area that is a circular area 30mm in diameter fitting into the hepatocystic duct angle. The same authors claim that 50% of these variations are a potential hazard during cholecystectomy (9).
The surgical consequences of failure to recognize this rare condition is to injury the biliary tract and especially transaction of the accessory cystic duct with resulted bile leakage or fistula, ligation of the duct or stricture of the secondary cystic duct. In order to avoid misdiagnosis of the real anatomy of the extrahepatic biliary tract somenone should perform preoperative endoscopic retrograde cholangiopancreatography and additionally intraoperative real-time cholangiograms. It is more important to pay attention to that rare congenital anatomy in case of laparoscopic cholecystectomy (10, 11, 12).

References
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2. Steger, C. - A very unusual anomaly of the cystic duct (clinical observation of the duplication of the cystic duct). Ann. Ital. Chir., 1956, 33:980.
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10. Fujikawa, T., Takeda, H., Matsusue, S., Nakamura, Y., Nishimura, S. - Anomalous duplicated cystic duct as a surgical hazard: report of a case. Surg. Today, 1998, 28:313.
11. Lobo, E.J., Herbella, F.A., Goldenberg, A., Kobata, M.H., Trivino, T. - Laparoscopic cholecystectomy in a patient with a duplicated cystic duct. Surg. Laparosc. Endosc. Percutan. Tech., 2000, 10:326.
12. Momiyama, T., Souda, S., Yoshikawa, Y., Kurantani, T., Toda, K., Koma, M. - Injury to a duplicated cystic duct during laparoscopic cholecystectomy. Surg. Laparosc. Endos., 1996, 6:315.

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