A prospective evaluation of anorectal function after total mesorectal excision in patients with a rectal carcinoma.

Background: Rectum resection with total mesorectal excision (TME) and neorectal anastomosis often compromises anorectal function. Insight into the underlying mechanisms is lacking. Therefore, a prospective study was designed to investigate the relationship between clinical and functional outcomes preoperatively and postoperatively.

Methods: Eleven patients with rectal cancer were examined before and 4 and 12 months after surgery and compared with 11 healthy volunteers (HVs). Anorectal (neorectal) function was examined by clinical outcome questionnaire, anal manometry, rectal compliance, and sensation. Six HVs also underwent barostat measurements in the sigmoid colon.

Results: Clinical parameters of soiling and passive incontinence (loss of stool without sensation) increased significantly until 12 months postoperatively, whereas urgency and tenesmus increased temporarily, returning to preoperative values at 12 months. In anorectal measurements, anal sphincter function was grossly preserved; however, rectal-anal inhibitory reflex (RAIR) was decreased at 4 months but recovered after 1 year. Neorectal compliance was similar to that of HV sigmoid, increasing slightly after 12 months but still significantly lower than that of normal rectum. Neorectal sensation to pressure distention was similar to that of normal rectum, however accompanied by smaller volumes. Neorectal distention induced contractions of large amplitude at 4 months, returning to normal after 12 months.

Conclusions: Our results suggest that the transient increase in urgency and tenesmus after surgery results from a temporary increase in neorectal "irritability" accompanied by some adaptation of compliance in time. In contrast, episodes of incontinence and soiling are increased after 1 year most likely because of reduced neorectal capacity and RAIR recovery in the presence of a low basal anal sphincter pressure.