33rd Annual Scientific Meeting proceedings

Introduction
Surgical approaches to the equine rectum can be challenging. Although well described in humans, the anatomy and the surgical access to the presacral space is lacking in horses. Our objectives were to describe the surgical anatomy of the presacral space and to investigate a surgical approach to the rectum using an endoscopic retroperitoneal approach.

Materials and methods
First, two equine cadavers were dissected to define the boundaries of the presacral space and optimal portal locations for the surgical approach. Then, eight cadavers were used for the retroperitoneoscopic procedure in a standing position, followed by dissection of the presacral space. Anatomical landmarks, portal locations and surgical anatomy were evaluated.

Results
The presacral space was bordered by the vertebral column from the lumbosacral promontorium to the first coccygeal vertebra dorsally, and by the presacral fascia and peritoneum ventrally. Lateral limits were composed of the sacrosciatic ligament and transversalis fascia. Cranial and caudal borders were composed of the peritoneum, and coccygeal and levator ani muscles respectively.

Optimal portal placements were located at 10 and 2 o’clock between the external anal sphincter and semimembranosus muscles and at 12 o’clock between the base of the tail and the external anal sphincter muscle. This allowed for complete exploration of the presacral space and adequate manipulation of the dorsal and lateral aspects of the rectum with standard laparoscopic instrumentation.

Discussion
Retroperitoneoscopic approach to the presacral space could offer new surgical possibilities in the treatment of affections of the dorsal and lateral aspects of the rectum.