Study objective: To determine the cephalocaudal relationship among the umbilicus, aortic bifurcation, and iliac vessels by direct measurement during laparoscopy.
Design: Prospective, consecutive study (Canadian Task Force classification II-1).
Setting: Tertiary referral center.
Patients: Ninety-seven women undergoing operative laparoscopy.
Interventions: The distance from the aortic bifurcation relative to the umbilicus was measured in both the supine and Trendelenburg positions with a marked suction-irrigator probe. Patients were stratified into three groups based on body mass index (kg/m2). The anatomic location of the common iliac vessels and course of the left common iliac vein were identified in 68 women.
Measurements and main results: The position of the aortic bifurcation ranged from 5 cm cephalad to 3 cm caudal to the umbilicus in the supine position, and from 3 cm cephalad to 3 cm caudal in the Trendelenburg position. In the supine position, the aortic bifurcation was located caudal to the umbilicus in only 11% of patients compared with 33% in the Trendelenburg position. This difference was statistically significant for the total study population (p <0.0001) and for the nonoverweight group (p <0.01). In both positions no significant correlation was found between the distance from the aortic bifurcation to the umbilicus and body mass index. Mean +/- SD distance of the aortic bifurcation from the umbilicus in the supine position was 0.1 +/- 1.2 cm for the nonoverweight group, 0.7 +/- 1.5 cm for the overweight group, and 1. 2 +/- 1.5 cm for the very overweight group. Respective values in Trendelenburg position were 1.0 +/- 1.1, -0.4 +/- 1.2, and -0.2 +/- 1.3 cm. The common iliac artery was caudal to the umbilicus in four women. The space between common iliac arteries was always at least partly occupied by the left common iliac vein, and was completely filled in 19 women (28%).
Conclusions: The cephalocaudal relationship between the aortic bifurcation and umbilicus varies widely and is not related to body mass index in anesthetized patients. Regardless of body mass index, the aortic bifurcation is more likely to be located caudal to the umbilicus in the Trendelenburg compared with the supine position. Its presumed location can be misleading during Veress needle or primary cannula insertion, and a more reliable guide is necessary for this procedure to avoid major retroperitoneal vascular injury.