Growing interest of surgeons in anterior approach to lumbar spine has demonstrated its vascular complications. A clear delineation of vascular working window for operating lumbar spine, formed by inferior vena cava formation and Aortic bifurcation is important to avoid dangerous complication. This study determines common level of Aortic bifurcation at the body of L4, with average distance of 34mm from lower border of L5-S1 disc. Variable level of iliocava junction (formation of inferior vena cava) was noted from body of L4 to L5-S1 disc, with average distance of 17mm from lower border of L5-S1 disc. Average width of inferior vena cava measured maximum at its formation i.e. 28mm. Width of right and left common iliac vein found almost equal. Angle made by left common iliac vein with inferior vena cava found most variable whereas that with right common iliac vein was constant. Average interiliac angle was 72.5 degrees. Left common iliac vein showed average 3 tributaries while right showed none or 1.

Key words: Iliocava junction; Aortic bifurcation; Lumbosacral spine.