Level of the anastomosis does not influence functional outcome after anterior rectal resection for rectal cancer

Anorectal function was studied in 55 patients undergoing low anterior resection for rectal adenocarcinoma. Patients were examined preoperatively and 3 months postoperatively by anorectal manometry and standardized interview. Postoperatively, the patients showed, in general, an impairment of anorectal functions. After 3 months, continence for flatus was defective, the ability to discriminate flatus from feces, and the ability to defer defecation were compromised. Stool frequency was elevated, and anal resting pressure, squeeze pressure, and rectal compliance were decreased. The rectoanal inhibitory reflex was abolished in all patients. However, the two groups with the level of the anastomosis less than or equal to 6 cm (n = 27, range 3 to 6) and more than 6 cm (n = 28, range 7 to 10) above the anal verge showed no differences in manometric values, stool frequency, or fecal continence assessed by the interview. No correlation was found between the level of the anastomosis and manometric values and between the level of the anastomosis and stool frequency (regression analysis = not significant). We concluded that anorectal function after anterior resection and low colorectal anastomosis are not influenced by the remaining length of the rectum but by the surgical trauma to the sphincter and its innervation.