Transanal Excision
What the Examiner Expects
Local full-thickness excision of rectal lesions performed transanally, either directly (for distal rectal lesions within reach of retractors) or using a transanal platform (TAMIS — transanal minimally invasive surgery, or TEO — transanal endoscopic operation) for mid-rectal lesions. The examiner expects you to know the criteria for local excision of early rectal cancer: T1 tumor, well to moderately differentiated, no lymphovascular invasion, < 3 cm, involves < 30% of the rectal circumference, and limited to sm1 submucosal invasion. Full-thickness excision with a 1 cm margin must be achieved. If final pathology shows unfavorable features (poor differentiation, LVI, sm2-3 invasion, positive margins), the patient should undergo completion radical resection (LAR or APR).
Key Examiner Focus Points
- Indicated for benign polyps and selected T1 rectal cancers with favorable features
- Favorable T1 features: well-differentiated, no lymphovascular invasion, < 3 cm, < 30% circumference, sm1 invasion
- Full-thickness excision with 1 cm margins
- TAMIS (transanal minimally invasive surgery) or TEO platforms for mid-rectal lesions
- If pathology shows unfavorable T1 or T2: recommend radical resection (TME)
Common Curveballs
Final pathology shows T1 with lymphovascular invasion
This is an unfavorable T1. The lymph node metastasis rate is approximately 10–15%. Recommend completion radical resection with TME (LAR or APR depending on tumor location). Local excision alone is inadequate for unfavorable T1 tumors.
The lesion is at 10 cm from the anal verge — too high for standard transanal approach
Use a transanal platform (TAMIS with a GelPOINT Path or TEO) which provides insufflation and visualization for mid-rectal lesions up to 12–15 cm. This allows full-thickness excision of lesions out of reach of standard retractors.
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