Anorectal sphincter function and rectal barostat study in patients following transanal endoscopic microsurgery

Background and aims: This study evaluated the effect of transanal endoscopi c microsurgery (TEM) on anorectal sphincter functions and determined the ri sk factors for anorectal dysfunctions (including incontinence). Patients an d methods: A study group of 33 patients with small, mobile rectal tumors (a denoma and carcinoma) located up to 12 cm from the anal verge underwent ano rectal motility studies (using pull-through anorectal manometry and rectal barostat) and endoanal ultrasound prior to surgery and 3 weeks and 6 months after TEM; controls were 20 healthy volunteers. Results: Resting and squee ze anal pressures were reduced 3 weeks after TEM. Resting anal pressure rem ained reduced 6 months after surgery; the changes were related to low preop erative levels and to the internal anal sphincter defects rather than to th e procedure duration or the type of surgery. High-pressure zone length and vector volume were decreased 3 weeks after TEM and restored 6 months later. Rectoanal inhibitory reflex, reflex sphincter contraction, rectoanal press ure gradients, threshold and maximal tolerable volume of rectal sensitivity , and compliance were significantly changed 3 weeks after TEM, only rectal wall compliance remained low at 6 months. The rectoanal inhibitory reflex, reflex sphincter contraction, rectal sensitivity, and compliance were relat ed to the extent and type of excision (partial or full thickness). Anal ult rasound revealed internal anal sphincter defects in 29% of patients studied 3 weeks after TEM. Only 76%, of patients were fully continent. Disturbed a norectal function (including partial fecal incontinence) was observed in up to 50% of patients at 3 weeks. Partial and moderate anorectal dysfunction was found in 21% patients 6 months after surgery. The main risk factors of anorectal dysfunctions following TEM included: postoperative internal anal sphincter defects, low preoperative resting anal pressure, disturbed rectoa nal coordination, extent (>50% of wall circumference) and the depth (full t hickness) of tumor excision. Conclusion: TEM has a relevant but temporary e ffect on anorectal motility. As a result of TEM procedures 21% of the patie nts had disturbed anorectal functions, mostly due to the extent or depth of tumor excision (influencing rectal compliance and rectoanal coordination), and to the sphincter defects lowering resting anal pressure. Preoperative anorectal motility studies and anal ultrasound allow the identification of patients with the risk of postoperative anorectal dysfunctions.