الفهرس 
Embryology of the biliary systemOnly 14 pages are availabe for public view
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Abstract
Over the past decade, a critical shortage of cadaveric organs for adults in need of liver transplants has developed. The current mortality for patients awaiting liver transplantation (LT) ranges from 20% to 30%. During this decade , the waiting period for LT and the mortality among patients on waiting lists have increased by a factor of more than 10 while the donor pool has expanded only marginally. (Broering et al., 2003)
The use of adult-to-adult right lobe living donor liver transplantation (LDLT) provides an alternative technique to reduce the waiting list mortality. In this technique, the transplant candidate gains survival time and better quality of life while the proven healthy donor undergoes liver resection for living donation of right or left lobe. (Broering et al., 2003)
Besides augmenting the transplant organ pool, LDLT provides the advantages of performing an elective operation, having access to a graft in best condition, and lowering the likelihood of recipient death, while waiting for a suitable organ. Supported by improved surgical technique and immunosuppression, LDLT results in recipient survival rates comparable with those obtained after conventional liver transplantation with full-sized cadaveric organs. (Settmacher et al., 2004)
The greatest risk in LDLT is the death of the donor which is estimated to range between 0.1% to 0.5%. ( Brown et al., 2003)
Furthermore, a potentially uneventful outcome of the recipient is a psychological threat for the donor. Therefore, donor safety has the highest priority when LDLTx is performed, and selection criteria and management of living donors requires continuous refinement.( Brown et al., 2003)
One reason for this drawback is seen in a high number of either unrecognized or, during the operation, extemporaneously handled biliary and vascular variants. To reduce such risk to a minimum, and also to ensure optimal surgical results in the recipient, the donation candidates have to undergo an extensive stepwise-fashioned evaluation process before being admitted for donation. After overcoming the psychological barriers of agreeing to donate part of an organ, the thorough anatomic study of the donor’s liver is of major importance. Special attention is given to the determination of the liver volumes and the recognition of vascular and biliary anomalies. In fact, a majority of the candidates are eliminated mostly because of unfavorable hepatic parenchymal, biliary, or vascular morphology. (Brandhagen et al., 2003)
Bile duct leak and stenosis impact morbidity and mortality in the early and late phase after LT. After LDLT, only few studies focused on anatomical variations of the biliary tree, which is the rule rather than the exception in liver surgery. In LDLT, anatomic variations of intra-hepatic bile ducts can complicate both, the donor and the recipient operation. Full hepatic lobectomy is required for adult-to-adult LDLT, and the postoperative risk is greater after right lobe resection. Peroperative delineation of the biliary system appears important to achieve a successful outcome. (Ohkubo et al., 2004)
In conventional anatomy, the right posterior duct (which drains Couinaud segments VI and VII) joins the right anterior duct (which drains Couinaud segments V and VIII) to form the right hepatic duct, which then joins the left hepatic duct (which is formed by ducts draining Couinaud segments II, III, and IV). All other anatomic configurations are considered variant. (Pan and Yan, 2006)
Accurate assessment of the biliary anatomy is known to have a major effect on the postoperative results. Failure to recognize even minor intra-hepatic branches crossing the dissection line can result in severe postoperative leaks and other complications. Even though the preoperative information rarely leads to exclusion of the donation process or a dramatic change of the surgical approach, awareness of biliary variations may prompt thorough exploration to localize the critical structures. (Malago et al., 2004)
The preoperative assessment of living liver donor candidates includes evaluation of second-order biliary tract anatomy because variant anatomy is seen in up to 45% of the population. Variant second-order biliary tract anatomy affects the surgical approach and biliary anastomotic technique and may preclude liver donation. Although Endoscopic Retrograde Cholangiography (ERC) is the standard test for defining biliary anatomy, it is invasive and has a complication rate of 1.4% to 3.2%.(Lee et al., 2001) The noninvasive evaluation of the biliary tract with Magnetic resonance cholangiography (MRCP) or computed tomographic (CT) cholangiography has shown promising results in small series. (Lee et al., 2001)
Although biliary variants can be readily depicted by means of intra-operative cholangiography, this procedure results in time delays and does not permit the surgeon to freely adjust the surgical strategy. (Lee et al., 2004)