The mesocolon: a prospective observational study

The aim of this study was to characterize formally the mesocolic anatomy during and following total mesocolic excision. Total mesocolic excision may improve survival in patients with colon cancer. Although this requires a detailed knowledge of normal and variant mesocolic anatomy, the latter is poorly characterized. No studies have prospectively characterized the anatomy of the entire mesocolon.

Total mesocolic excision was performed in 109 patients undergoing total abdominal colectomy. The mesocolon was maintained intact thereby permitting a precise anatomical characterization from ileocaecal to mesorectal levels. Two- and three-dimensional schematic reconstructions were generated to illustrate in situ conformation.

Several previously undocumented findings emerged, including: (i) the mesocolon was continuous from ileocaecal to rectosigmoid level; (ii) a mesenteric confluence occurred at the ileocaecal and rectosigmoid junction as well as at the hepatic and splenic flexures; (iii) each flexure (and ileocaecal junction) was a complex of peritoneal and omental attachments to the colon centred on a mesenteric confluence; (iv) the proximal rectum originated at the confluence of the mesorectum and mesosigmoid; and (v) a plane occupied by Toldt's fascia separated the entire apposed mesocolon from the retroperitoneum.

When the mesocolon is fully mobilized during a total mesocolic excision of the colon, several anatomical findings that have not been previously documented emerge. These findings provide a rationalization of the surgical, embryological and anatomical approaches to the mesocolon. This has implications for all related sciences.