Anal sphincter injuries from stapling instruments introduced transanally -Randomized, controlled study with endoanal ultrasound and anorectal manometry

PURPOSE: Injury sustained from the transanally introduced stapling techniqu e was assessed by comparison with biofragmentable anastomotic ring anastomo sis, which excluded anal manipulation. METHODS: A randomized, controlled tr ial was conducted on consecutive patients undergoing sigmoid colectomy (whe re pelvic nerve injury was avoided). A bowel function questionnaire was adm inistered six months after surgery. Anorectal manometry and endoanal ultras onography were performed preoperatively and at six months postoperatively. The observers were blinded to the randomization. RESULTS: There were 18 pat ients in the transanally introduced stapling technique group and 17 patient s in the biofragmentable anastomotic ring group, with no differences in age , gender, Dukes staging, and follow-up. Three of the transanally introduced stapling technique patients had occasional liquid soiling, which was absen t in biofragmentable anastomotic ring patients. Mean change in resting anal pressures was also significantly impaired when compared with patients with biofragmentable anastomotic ring (P = 0.007). Endosonographic internal sph incter fragmentation was found in five transanally introduced stapling tech nique patients but none after biofragmentable anastomotic ring anastomosis (P = 0.046). Internal sphincter fragmentation was associated with the impai red resting pressures (P = 0.007). External sphincter deficiencies were fou nd after transanally introduced stapling technique in two patients (biofrag mentable anastomotic ring = 0), and these were associated with the soiling (P = 0.005). CONCLUSIONS: The transanally introduced stapling technique may result in anal sphincter defects and impaired anal pressures when assessed at six months of follow-up.