The Heald classification of mesorectal planes describes three planes of dissection in rectal surgery. What defines the 'intramesorectal' plane, and why is it surgically undesirable?
- A Dissection within the mesorectal fat, producing an irregular surface and exposing cancer cells ✓
- B Dissection outside the mesorectal fascia; disrupts autonomic nerves
- C Dissection along the mesorectal fascia; optimal for total mesorectal excision
- D Dissection between the endopelvic fascia and the presacral fascia
Correct answer: A. Dissection within the mesorectal fat, producing an irregular surface and exposing cancer cells
Explanation
Heald described three planes: the mesorectal (ideal TME plane along the mesorectal fascia), the intramesorectal (suboptimal; dissection through the mesorectal fat creating an irregular 'coning' surface), and the muscularis propria plane (worst; dissection directly on the bowel wall). The intramesorectal plane is undesirable because it disrupts the mesorectal envelope, risks transecting tumour deposits or involved lymph nodes, and is associated with higher local recurrence rates compared to proper TME.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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