Long-term assessment of anorectal function after extensive resection of the internal anal sphincter for treatment of low-lying rectal cancer near the anus

Objectives: Intersphincteric resection (ISR) for low-lying rectal cancer (LRC) may induce major problems associated with anorectal function. In this study, we assessed the severity of ISR-induced impairment in anorectal function. Methods: In total, 45 patients followed up regularly ≥2 years after diverting ileostoma closure were eligible. The patients underwent ISR (n=35) or conventional coloanal anastomosis without resection of the internal anal sphincter (IAS) (n=10) for treatment of LRC from January 2000 to December 2011. We retrospectively compared anorectal function [stool frequency, urgency, Wexner incontinence scale (WIS) score, and patient satisfaction with bowel movement habits on a visual analog scale (VAS) score] for ≥2 years after stoma closure between the two groups. Results: The median follow-up period was 4.0 years (range, 2.0-6.5 years). Of the total, 17 (48.6%) patients who underwent ISR had poor anorectal function, including two with complete incontinence. Significant differences were found between the groups in the incidence of urgency (p=0.042), WIS score (p=0.024), and defecation disorder with a WIS score of ≥10 (p=0.034) but not in stool frequency. Based on the VAS score, 45.7% of patients who underwent ISR were dissatisfied with their bowel movement habits (p=0.041). Conclusions: Extensive resection of the IAS has negative short- and long-term effects on anorectal function.