Anatomical variations of the iliolumbar vein with application to the anterior retroperitoneal approach to the lumbar spine: a cadaver study.

Objectives of this study include identification of lumbosacral venous variations, designation of a critical area of dissection for surgical exposure, and comparison between both male/female and right/left-sided anatomy. Attempts were made to provide anatomic nomenclature that accurately describes these structures. Thirty-eight iliolumbar venous systems in 20 cadavers (11 females/9 males) were dissected. Each system was identified as one of three patterns of variation: common venous trunk (combining ascending lumbar and iliolumbar venous systems) with distal veins, common venous trunk without distal veins, and venous systems without a common venous trunk. Dimensions including distances to the inferior vena cava (IVC) confluence, the obturator nerve, and the lumbosacral trunk, and venous stem length were obtained to aid surgical dissection. Differences between males and females and those between right and left sides were compared. Anterior lumbosacral venous variations could be organized into three groups. A Type 1 venous system (common venous trunk with distal veins) was most common (53% of systems). The anatomical name "lateral lumbosacral veins" adequately describes the anatomical location of these veins and does not assume a direction of venous flow or the lack of individual distal veins. A critical area bordered by the obturator nerve anteriorly, the psoas muscle laterally, the spinal column medially, and sacrum posteriorly within 8.2 cm of the IVC confluence should be defined to adequately dissect the lateral lumbosacral veins. Differences in male and female lateral lumbosacral venous anatomy do not alter surgeon's approach to the anterior lumbar spine. (c) 2008 Wiley-Liss, Inc.