Anatomic Zone of Safety of the Presacral Space

As the trend toward minimally invasive sacrocolpopexy grows, the effect of reduced haptic feedback on facilitating safe dissection and suture placement has become more apparent. Knowledge of neurovascular anatomy and how the anterior longitudinal ligament (ALL) thickness varies in the presacral space may help guide suture and mesh placement as well as depth of tissue purchase.

The objectives of this observational study were to characterize the key vascular anatomy of the presacral space, assess variations in ALL thickness in the mediolateral direction and seek a "safe zone" for suture placement.

The key vascular anatomy of the presacral space, below the aortic bifurcation to the S2 vertebra level, was examined in unembalmed female cadavers. Distances of key vascular structures from the midline were also determined. After histologic processing, ALL thickness was measured, and its variation in the mediolateral axis evaluated.

Fourteen cadavers were dissected. Descending craniocaudally, iliac arteries and veins diverged from midline. The iliac vessels, aorta, and inferior vena cava did not cross a zone in the presacral space 1 cm above and below, 1 cm right, and 1.2 cm left of the midsacral promontory. The middle sacral artery , confined to a 1.5 cm wide vertical channel, was the most common vascular structure traversing the midline. The ALL appeared to gradually attenuate in the mediolateral axis, although not statistically significant.

An approximate 1 cm radius around the midsacral promontory may be a safer and potentially more substantive location for suture placement when compared with the lateral aspects of the ALL.