Anatomical variations of the internal iliac veins in the presacral area: Clinical implications during sacral colpopepxy or extended pelvic lymphadenectomy.

The purpose of this study was to classify anatomical variations of the internal iliac vein (IIV) in relation to robotic or laparoscopic extended lymphadenectomy. Between March 2011 and July 2012, 60 consecutive patients underwent robotic or laparoscopic extended lymphadenectomy. We retrospectively reviewed surgical video clips and analyzed the pattern of the IIVs in the presacral area. IIV variations were classified into seven types: Type A, normal (n = 39, 65.0%); Type A with a dilated middle sacral vein (n = 5, 8.3%); Type B, left IIV connecting centrally to the left external iliac vein (n = 5, 8.3%); Type C, a separated trunk of the left IIV draining into the left central common iliac vein (CIV; n = 1, 1.7%); Type D, a separated trunk of the right IIV draining into the left central CIV (n = 8, 13.3%); Type E, a separated trunk of the right IIV draining into the right central CIV (n = 0, 0%); and Type F, separated trunks of the bilateral IIV connecting with each other before draining into the left central CIV (n = 2, 3.3%). The prevalence of IIV anomalies was 26.7%; the incidence of separated IIV trunks was 18.3%. To prevent life-threatening IIV injury during extended lymphadenectomy or sacral colpopexy, the anatomical variations of the IIVs should be known exactly.