Fig. 8
From: MRI anatomy of the rectum: key concepts important for rectal cancer staging and treatment planning
Schematic drawing and total mesorectal excision (TME) resection specimen showing the mesorectal fascia (inked in green in TME specimen) extending up until the level of the peritoneal reflection (black arrow) anteriorly. From this level upwards, the mesorectum is covered by peritoneum anteriorly in the mid-rectum, and anterolaterally in the high rectum. Invasion of the peritoneum including the anterior peritoneal reflection entails cT4a disease (a, b). Invasion of the MRF is classified as cT3 MRF + disease. Note that invasion of the MRF may co-occur with invasion of the peritoneum, in which case the tumour stage is cT4a MRF + (a)