Caterpillar hump of right hepatic artery: incidence and surgical significance

Abstract

Background and aims : The right hepatic artery occasionally forms a sinuous tortuousity called as caterpillar hump or Moynihan's hump, which occupies the major portion of Calot's triangle. Due to this variation, inadvertent injury to right hepatic artery may occur during surgical procedures. The aim of the study is to find out the incidence of Caterpillar hump of right hepatic artery in cadavers and to correlate with surgical significance. Materials and methods : Sixty cadavers allotted for the purpose of teaching undergraduate students from the period of 2006 to 2011 were used for this study. Branches of coeliac trunk were traced and right hepatic artery was observed for the presence of caterpillar hump. Results : Caterpillar hump was noted in three out of 60 cadavers (5%). Out of three specimens with caterpillar hump, right hepatic artery passed posterior to common hepatic duct in two specimens and anterior to it in one specimen. The presence of dual loops of right hepatic artery was noted in two specimens and single loop was observed in one specimen. Conclusion: The presence of this variant course of right hepatic artery may lead to the formation of short cystic artery. Thereby, right hepatic artery can be mistaken for cystic artery and may be injured during surgical procedures. The knowledge of caterpillar hump of right hepatic artery is essential for the surgeons to avoid the risk of ischemic necrosis of right lobe of liver.

The unwanted third wheel in the Calot's triangle: Incidence and surgical significance of caterpillar hump of right hepatic artery with a systematic review of the literature

“…Nine studies[131521222324252627] reported data from a total of 498 human cadavers used for anatomical dissection purpose ranging from 1[21] to 90[22] specimens per study; six studies[12028293031] performed the research on a total of 579 patients submitted to cholecystectomy for symptomatic cholelithiasis, ranging from 1[129] to 200[28] patients per study [Table 1]. Only the study by Benson and Page[32] involved 140 patients submitted to cholecystectomy and 65 human cadavers as well.…”

“…Only the study by Benson and Page[32] involved 140 patients submitted to cholecystectomy and 65 human cadavers as well. The majority of studies were conducted in single Eastern centres (188 cholecystectomies, 32.5% and 308 cadavers, 61.8%) (India, Saudi Arabia, Pakistan, Iraq, Japan),[11315202122232426272930] while the five others were performed in the Western and American Countries (391 cholecystectomies, 67.5% and 190 cadavers, 38.2%) (United Kingdom, Yugoslavia, Croatia, USA). [2225283132]…”

“…Only eight articles[113152123242627] reported the relationship between the caterpillar hump and the common bile duct as well as the characteristics of loop configuration. The tortuous artery was found to route anteriorly to the common hepatic duct in 40% of cases and posteriorly in 60%, representing the posterior presentation the more common anatomical route.…”

“…[1112] Although several variations in the origin and branching pattern of hepatobiliary triangle arteries have been reported,[11113] the tortuous right hepatic artery configuring an insidious hump represents one of the most considerable and dangerous anomalies. In this extremely rare configuration called caterpillar hump or Moynihan's hump,[1415] the right hepatic artery runs very close to the gallbladder and cystic duct, forming a U-shaped loop, where the cystic artery starts in exceptionally short fashion. [16] This route consistently predisposes to misidentification as well as vulnerability of vascular structures with inappropriate clipping or uncontrollable bleeding.…”

A Study of Variant Hepatic Arterial Anatomy and Its Relevance in Current Surgical Practice

“…Presence of tortuous right hepatic artery (caterpillar hump) may lead to vascular injuries during surgical procedures in this region as such an artery is closer to the cystic duct and the cystic artery is short. It is important for surgeons to know this variant to avoid inadvertent ligation of right hepatic artery CONCLUSION instead of cystic artery, thereby preventing vascular injuries and the fatal ischaemic necrosis of right lobe of the liver [23].…”