Anatomy of the internal iliac vein around the sacral promontory based on CT three-dimensional (3D) reconstruction

The area around the sacral promontory (SP) is the targeted location of various pelvic operations. We examined the internal iliac vein (IIV) configurations around the SP by computed tomography angiography (CTA) three-dimensional (3D) reconstruction to describe its anatomy and provide accurate anatomical parameters for relevant operations to reduce intraoperative vascular injury. We retrospectively studied 2078 CTA 3D model datasets from Nanfang Hospital patients examined for gynecological diseases from December 2009 to October 2020. The IIVs of the above cases were divided into standard and variant IIVs, and variant IIVs were subdivided into different subtypes. To compare the size of the avascular area around the SP between standard and variant IIVs, we selected the two subtypes with the highest variation rate for comparison with the standard IIV type. The most common types of variant IIVs were 5a (5.15%) and 3a (5.05%). The results showed larger values in the standard group than in the 3a and 5a groups for the confluence of common iliac vein (CCIV) height (37.73±12.05 vs. 28.93±10.17 vs. 27.27±7.58 mm, P < 0.05), distance between the iliac vessels (49.47±9.47 mm vs. 37.08±9.36 vs. 37.73±8.94 mm, P < 0.05), and SP exposure width (44.94±6.39 mm vs. 36.83±8.29 vs. 36.93±7.91, P < 0.05). Variant IIVs may increase the risk of surgery by reducing the avascular area compared with standard IIVs. Therefore, when operating around the SP, special attention should be given to variant IIVs and avoiding vascular injury.