Risk of Bleeding from the Internal Iliac Artery and Its Branches in Pelvic Fractures: Cadaver Study

PURPOSE OF THE STUDY The study was designed to investigate whether anatomical variations of the anterior and posterior divisions of the internal iliac artery and their branches are associated with different risks of bleeding resulting from injury to the posterior pelvic segment. MATERIAL AND METHODS The study was carried out on 19 cadavers. The dissected area included the internal iliac artery from the common iliac artery bifurcation to the origins of the superior gluteal artery, the inferior gluteal artery and the internal pudendal artery. Using an electronic slide rule, distances between the bifurcation and the origin of each branch from either the anterior or the posterior division were measured. The diameter of each vessel was also determined. Findings of the study were compared with variations described in the literature. The degree of risk for bleeding related to different anatomical variations of the internal iliac artery and its branches was evaluated based on the proximity to the bone. RESULTS There are six anatomical variations of internal iliac artery branches. Four of them were found: type A1 was recorded in 10 specimens, type A2 in six, type B1 in two and type C in one specimen. Types B2 and D were not seen. DISCUSSION The type B2 and C anatomical variations were considered to carry higher risks of bleeding due to injury to the posterior pelvic segment. These variations are characterized by vessels larger in diameter and a longer course of the posterior division along the posterior part of the greater sciatic notch (area often involved in unstable pelvic ring fractures). On the other hand, the type C variation showed a longer internal iliac artery separated from the bone with a thick layer of soft tissue, which suggested lower risk than was attributed to the dominant type A1 variation. It was not possible to evaluate type B2 variation because it is very rare and was not found in study material. In type A2 and B1 variations, the branches were separated from bony structures similarly to the dominant type A1 variation. CONCLUSIONS The cadaver study designed to assess the risk of bleeding associated with different morphological variations of the branching pattern of the internal iliac artery did not identify any anatomical arrangement that might carry a higher risk of injury to the vessels by free bone fragments of the posterior segment in unstable pelvic fractures. It can be concluded that less common branching patterns of the internal iliac artery are not associated with higher risk of bleeding than the dominant type A1 variation.