Anatomical variations of the position of the aortic bifurcation, iliocava junction and iliac veins in relation to the lumbar vertebra.

OBJECTIVE To determine the position of the aortic bifurcation and the iliocava junction in relation to the lumbar vertebra, aortic bifurcation angle, interiliac angle, and anatomical variation of the iliac veins anterior to the lumbar vertebra of Thai people. MATERIAL AND METHOD The present study was done on 65 cadavers. The mean ages of the cadavers were 73 +/- 10 years (range from 50 to 90 years). The dissections were performed by anterior approach to the lumbar vertebra. The position of the aortic bifurcation and the iliocava junction, aortic bifurcation angle and interiliac angle were measured in relation to the lumbar vertebra. Anatomical variations of the iliac veins were observed anterior to the lumbar vertebra. RESULTS The aortic bifurcation was between L3 and L5, most often at the L4 vertebral body level (63%), at the middle third in vertical plane of vertebra (31%) and at the median third in horizontal plane of vertebra (57%). The iliocava junction was between L4 and L5-S1 disc, most often at the L5 vertebral body level (69%), at the upper third of vertebra (28%) and at the right lateral third in horizontal plane of vertebra (60%). The mean aortic bifurcation angle was 54 degrees (male 55 degrees, female 53 degrees. No significant difference in the mean aortic bifurcation angle was observed between male and female at p > 0.05 and the mean interiliac angle was 71 degrees (male 73 degrees, female 68 degrees). A significant difference in the mean interiliac angle was observed between male and female at p < 0.05. In the abdomen, variation of common iliac vein was found on the left side connecting IVC with left external iliac vein. CONCLUSION The anatomical variations of the position of the aortic bifurcation, iliocava junction, and common iliac veins at the anterior of lumbar vertebra can be found in a normal population and cause trouble to vertebral surgery during the operation. Therefore, precaution and full investigation of the anatomical position of the vessels might be required before surgery is performed.