Venovertebral vein: Morphometric analysis and significance for the transabdominal spine surgeon

Study Design: Prospective intraoperative findings review. Objectives: To describe the surgical anatomy of the innominate vessel, venovertebral vein, and consider its significance for transabdominal surgery. Background Data: It has not described in any anatomy textbook or reported papers. Materials and Methods: In 50 patients who underwent anterior lumbar interbody fusion or total disc replacement, we found venovertebral vein in 37 patients (74%). The connection between venovertebral vein and the left common iliac vein was studied to determine where the venovertebral vein drained, and its relationship to the iliolumbar vein and middle sacral vein. All parameters were measured with vernier caliper and divider. Results: All of the veins studied drained into the posterior margin of the left common iliac vein from the L5 vertebral body and were located between the iliolumbar vein and the middle sacral vein. The diagonal-vertical direction to the vertebral endplate was 64.8% (n = 24). The mean diameter of venovertebral veins was 2.24 +/- 0.74 mm (range 1.0 to 3.8 mm). The mean length was 12.71 +/- 5.71 mm (range 5.45 to 35.10 mm). The distance from the L5 vertebral upper endplate to its origin ranged from 6.05 to 21.25 mm, with a mean of 12.51 +/- 3.36 mm. The distance of the 37 venovertebral veins studied from the middle sacral vein ranged from 0 to 10.6 mm, with a mean of 5.75 +/- 2.90 mm. The distance from the iliolumbar vein ranged from 14 to 38 mm, with a mean of 22.65 +/- 5.44 mm. The venovertebral vein was found to be closer to the middle sacral vein than to the iliolumbar vein statistically (P < 0.05). Conclusions: The surgeon performing transabdominal spine surgery especially at the L4-5 level must remain alert to the existence of this innominate vein.