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Background: Anatomical variations of the human body including the extra hepatic
biliary system exist across various individuals. Understanding the variant anatomy of
the extrahepatic biliary system and its blood supply should aid surgeons in avoiding
iatrogenic injuries. This is important in resource limited settings where it is not
possible to perform adequate radiological investigations of the hepatobiliary system
prior to surgery. Local studies have only focused on cystic artery variations; however,
this study aims to assess variations in both the extrahepatic biliary system and its
blood supply.
Objective: The study described the anatomic variation of the extrahepatic biliary
system and its blood supply among Kenyans.
Methods: This was a cross-sectional study conducted at Moi University‟s Anatomy
Laboratories among 42 adult cadaveric specimens. Specimen dissections were
conducted as per the fifteenth edition of Cunningham‟s manual of Practical Anatomy.
The variant anatomy data collected were filled in a structured data collection form,
analyzed and presented using descriptive statistics.
Study Findings: Of the 42 cadavers sampled, 62% (n=26) were male while 38%
(n=16) were female. All the cadavers had a gall bladder being drained by the cystic
duct. The length of the cystic duct ranged between 7mm to 35 mm with a median
value of 17mm, and it joined the common hepatic duct to form the common bile duct
in 98% (n=41) of all the cadavers sampled. This confluence was to the left in 7.1%
(n=3), right 42.9% (n=18), anteriorly in 14.3% (n=6) and posteriorly 35.7% (n=14). A
single cadaver (2%) had the cystic duct drain into the right hepatic duct. Two thirds
(66.7%; n=28) of the cadavers sampled had the confluence of the right and the left
hepatic duct outside the liver. There were no cholecystohepatic ducts in this study. Of
the study subjects, 71.4% (n=30) had a normal pattern of the extrahepatic supply
(Type 1). The normal origin of the right hepatic artery from the proper hepatic artery
or common hepatic artery was seen in 81% (n=34) a while 19% (n=8) had an aberrant
origin (Type 3 and 4) from the superior mesenteric artery. The course of the right
hepatic artery was anterior to common hepatic duct and common bile duct in 26.2%
(n=11) of all the cadavers. Less than half of the cadavers 43% (n=18) had a caterpillar
hump of the right hepatic artery occupy the Calot‟s triangle. All cystic arteries were
within the Calot‟s triangle; however, 45.2% (n=19) of the cystic arteries arose from
the right hepatic artery outside the Calot‟s triangle anterior to the common hepatic
duct.
Conclusion: The study determined the existence of surgically important variant
anatomy of the extrahepatic biliary system and its blood supply among black
Kenyans. The caterpillar hump of the right hepatic artery occupying the Calot‟s
triangle was the most frequent variation.
Recommendation: There is need for greater appreciation of the extrahepatic biliary
system variant anatomy by both surgeons and radiologists so as to decrease morbidity
and improve on surgical outcomes. |
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