A case of delayed anastomotic fistula occurred nine years after adjuvant radiotherapy following rectal cancer surgery

The patient was a 72-year-old man who underwent a low anterior resection for rectal cancer in 2007 (RbRa, pT4a, pN1, cM0, pStage 3a). With the surgically stripped surface testing positive, the pelvic cavity was subjected to 50 Gy of radiation as part of adjuvant radiotherapy. In December 2015, the patient presented with anal pain and bloody stool.A CT scan revealed a pelvic abscess accompanied by gas patterns around the anastomotic site, and a colonoscopy detected formation of a fistula at the anastomotic site. Although CT-guided drainage was performed in response, a new abscess was formed promptly. In April 2016, laparoscopic colostomy with double orifices was performed on the transverse colon. Thereafter the abscesses in the buttocks required four sessions of incision and drainage. The condition improved with no purulent discharge after December 2016. As of 11 months after the colostomy, the pelvic abscess is gradually contracting, though some fistulas have remained. The patient has been followed up on an ambulatory basis.This case is considered to be of an intrapelvic abscess associated with the delayed anastomotic fistula occurred after a lapse of 9 years following irradiation. (author)