V93 - Transanal Minimally Invasive (TAMIS) Submucosal Dissection for Large Near-Circumferential Rectal Polyp

Purpose/Background: Transanal Minimally Invasive Surgery (TAMIS) is a well-established technique for treatment of benign and selected early-stage invasive lesions of the rectum. The approach extends the range of traditional transanal excision to the proximal rectum, is associated with low recurrence rates, and allows patients to avoid the morbidity of a radical proctectomy. While frequently employed for full-thickness excision, TAMIS is also an efficient technique for partial thickness removal of benign appearing lesions not amenable to standard endoscopic removal. We present a didactic video featuring the case of a patient with an extensive, near-circumferential spreading rectal polyp treated with TAMIS submucosal dissection.

Methods/Interventions: The patient is a 69 year old male referred for surgical management of a large spreading rectal mass discovered on cross-sectional imaging obtained to identify a source for MSSA bacteremia and sepsis. He reported no obstructive symptoms or pain but did admit to a history of bright red blood per rectum. He underwent a colonoscopy during this admission which demonstrated a near-circumferential, fungating, rectal mass extending to the anus. Biopsy demonstrated a tubulovillous adenoma. He recovered from his infection and a follow up sigmoidoscopy was performed 4 months later which re-demonstrated the mass extending roughly 15cm from the anal verge and repeat biopsy was concordant with previous results. The patient was offered treatment options including a proctectomy, but ultimate recommendation was made for en-bloc removal of the lesion by TAMIS to confirm the absence of invasive cancer. This was planned as a partial thickness resection to avoid violating perirectal dissection planes should a subsequent proctectomy be required. In addition to discussion of the usual procedural risks, the patient was counseled that additional surgery may be required if the lesion was found to contain invasive carcinoma or could not ultimately be removed by the transanal approach. The patient completed a combined mechanical and oral antibiotic bowel prep. For the procedure, the patient was placed in the lithotomy position and the transanal access port was placed. Submucosal injection lift aided in identification and initial dissection of the correct plane. En-bloc removal of the specimen was achieved using laparoscopic instruments for retraction and tension to expose the dissection plane and diathermy for dissection and hemostasis. There was no violation of the muscular layer of the rectal wall. Given the extent of the resection, the mucosal defect was left open to heal by secondary intention.

Results/Outcomes: The patient tolerated the procedure well and there were no complications. The patient was discharged the following day. The resected specimen measured 17cm (length) x 11cm (width) x 2.1cm (depth). Final pathology revealed villous adenoma with foci of high grade dysplasia, without invasive carcinoma. A small well-differentiated neuroendocrine tumor, grade 1, was also identified within the specimen. Surveillance endoscopy 6 months post procedure demonstrated two recurrent polyps in the mid-rectum which were removed by EMR and well-healed post-surgical site without evidence of stenosis. Pathology from the recurrent polyps revealed tubulovillous adenoma negative for high grade dysplasia.

Conclusion/Discussion: Submucosal dissection using TAMIS technique is effective for treating benign rectal polyps, including large expansive spreading lesions, and avoids the morbidity associated with proctectomy.