Rectal Anatomical Divisions for Cytoreductive Surgery Planning
The rectum is divided into three clinically relevant segments: upper, middle (or mid), and lower rectum. These divisions guide the choice of dissection plane, extent of mesorectal excision, and assessment of tumor involvement during cytoreductive procedures for advanced ovarian cancer [1][2].
Upper Rectum
- Extends from the rectosigmoid junction to the upper border of the sacral promontory.
- Located above the peritoneal reflection; peritoneal coverage facilitates mobilization.
Middle (Mid) Rectum
- Extends from the upper border of the sacral promontory to the lower border of the sacrum (approximately S3–S4 vertebral level).
- Lies within the mesorectal fat envelope; mesorectal fascia is well‑developed, allowing total mesorectal excision.
Lower Rectum
- Extends from the lower border of the sacrum to the anorectal ring.
- Mesorectum is thin or absent, making precise assessment of tumor‑mesorectal relationships critical [3].
- Dissection must respect the interface between the rectovaginal septum and mesorectal fascia to avoid injury to adjacent structures [4].
Surgical Implications
- Upper rectal involvement may be addressed via mobilization of the sigmoid colon and division of the peritoneal reflections.
- Middle rectal disease requires complete mesorectal excision within the well‑defined fascia.
- Lower rectal disease mandates careful identification of the thin mesorectal layer and preservation of the autonomic nerves within the rectovaginal septum.
These anatomical divisions provide a framework for planning the extent of rectal resection and for selecting appropriate dissection planes during cytoreductive surgery in advanced ovarian cancer.