Clinical Anatomy of the Presacral Space

Objectives: To characterize the anatomy of the presacral space, including the boundaries and relevant vascular, neural, and skeletal contents. We aim to correlate anatomic knowledge with clinical applications including avoidance of complications during gynecologic surgery with a focus on sacrocolpopexy.

Methods: Photos of cadaveric dissections and surgical video footage are used to demonstrate critical anatomy.

Clinical Relevance: The presacral space is a complex extraperitoneal surgical space accessed for a variety of gynecologic procedures including sacrocolpopexy and presacral neurectomy. The clinical presacral space extends from the aortic bifurcation superiorly to the pelvic floor muscles inferiorly. The anterior surfaces of the fifth lumbar vertebra, L5-S1 disc, and sacrum together form the posterior boundary. Anteriorly, the space is bounded by the rectosigmoid and the posterior peritoneum of the abdominal cavity and encompasses the ureters laterally. The lateral boundaries are defined by the common and internal iliac vessels.
The sacral promontory is the upper anterior surface of the first sacral vertebra and can be appreciated by the acute 60 degree angle of descent between the L5 and S1 vertebra. These vertebrae are connected by the L5-S1 disc, which is the most visually prominent structure within the space and extends 1.8 cm cephalad from the sacral promontory. The anterior longitudinal ligament attaches to the anterior surface of each vertebra and ranges in thickness from 1-2 mm. The left common iliac vein is the closest cephalad and left lateral vessel from the midsacral promontory, located on average 2.7 cm superiorly but can be as close as 9 mm. A complex makeup of vasculature sits atop the anterior sacral surface, including the middle sacral artery and veins, the lateral sacral veins, and the sacral venous plexus, which pose significant bleeding risk due to their highly variable nature. The superior hypogastric plexus, containing sympathetic and visceral afferent fibers, forms below the aortic bifurcation to the left of midline then divides into the bilateral hypogastric nerves at the level of the first sacral vertebra. The right sacral sympathetic trunk, which sits atop the anterior sacrum, and the right S1 nerve root are 2.3 and 2.6 cm lateral from the midsacral promontory, respectively.
Anatomy pertaining to presacral space surgical entry and complications is detailed. Relevant risks include hemorrhage of the vulnerable left common iliac vein or sacral venous plexus, nerve entrapment of the adjacent S1 nerve root or sympathetic trunk, and spondylodiscitis from deep placement of graft fixation sutures or bone tacks. We review the rationale for sacrocolpopexy graft placement below the sacral promontory on the surface of the S1 vertebra. In conclusion, this video demonstrates the complex presacral space anatomy relevant to gynecologic surgery and illustrates key anatomic principles to avoid neurovascular and skeletal complications.