The Middle Rectal Artery: Revisited Anatomy and Surgical Implications of a Neglected Blood Vessel.

BACKGROUND

Although the middle rectal artery is a relevant anatomical landmark for rectal resection and lateral lymph node dissection, descriptions of this entity are highly divergent.

OBJECTIVE

Dissection, visualization, morphometry, and 3-dimensional reconstruction of the middle rectal artery to facilitate its management in surgery.

DESIGN

Macroscopic dissection, histologic study, morphometric measurements, and virtual modeling.

SETTING

University laboratory of applied surgical anatomy.

PATIENTS: This study includes formalin-fixed hemipelvis specimens (n=37) obtained from body donors (age, 67-97 y).

MAIN OUTCOME MEASURES: The main outcome measures are photo documentation of origin, trajectory, diameter, and branching pattern; immunolabeling of lymphatics; and 3-dimensional reconstruction of the middle rectal artery.

RESULTS

The middle rectal artery was present in 71.4% of body donors (21.4% bilateral, 50% unilateral), originated from the anterior division of the internal iliac artery, and branched either from the internal pudendal artery (45.5%), the inferior gluteal artery (22.7%), the gluteal-pudendal trunk (22.7%), or a trifurcation (9.1%). One to 3 branches of varying diameters (0.5-3.5 mm) entered the mesorectum from the ventrolateral (35.7%), lateral (42.9%), or dorsolateral (21.4%) aspect. The middle rectal artery was accompanied by podoplanin-immunoreactive lymphatic vessels and gave off additional branches (81.8%) to the urogenital pelvic organs. Three-dimensional reconstruction revealed the complex course of the middle rectal artery from the pelvic sidewall through the pelvic nerve plexus and parietal pelvic fascia into the mesorectum.

LIMITATIONS: Findings retrieved from body donors may be prone to age- and fixation-related processes.

CONCLUSIONS

The investigation disclosed the rather high prevalence of the middle rectal artery, its 3-dimensional topographic anatomy, and its proximity to the autonomic pelvic nerves. These features play a role in the surgical management of this blood vessel. The data provide the anatomical rationale for the lateral lymphatic spread of rectal cancer and an anatomical basis for nerve-preserving lateral lymph node dissection.