EP479 - A Rare Case of a Colorectal Fistula with Abscess from Diverticular Disease

Image or Table (Do Not add text here):

Purpose/Background: Diverticular disease complicated by colorectal fistula is rare. Common fistulas that can develop in diverticular disease are colovesical, colovaginal, colouterine, colocutaneous, and coloenteric fistulas. Colovesical fistulas are more common in males than females as the uterus tends to prevent development of fistulas. We present the case of a colorectal fistula with abscess in a 57-year-old diabetic male with a two year history of abdominal discomfort, bloating, constipation and known kidney stones. Computed tomography (CT) scan demonstrated right sided hydronephrosis with ureteral calculus and small 2 cm abscess near the proximal rectum with fistulous connection to the sigmoid colon. Labs showed a leukocytosis of 12.7. A preoperative colonoscopy revealed sigmoid diverticulosis without evidence of malignancy and no obvious fistula.

Methods/Interventions: The patient underwent a robotic low anterior resection with a primary anastomosis between the descending colon and mid-rectum without the need for a diverting loop ileostomy. Intraoperatively, he was found to have an inflamed loop of sigmoid colon adherent to the proximal rectum. Separating the sigmoid colon from the proximal rectum demonstrated the associated abscess and a defect in the wall of the proximal rectum consistent with a fistula.

Results/Outcomes: Pathology was consistent with diverticulitis. He did not require postoperative antibiotics. His urinary catheter was removed immediately after surgery and he was started on low fiber diet POD0. The patient met criteria for discharge on POD1 and had an uneventful recovery at home.

Conclusion/Discussion: Formation of colorectal fistula due to diverticulitis is extremely rare and is attributed to the intraperitoneal mobility of the sigmoid colon allowing it to fold into the anterior peritoneal reflexion in close proximity of the rectum. CT is a sensitive test for diagnosing diverticular disease complicated by fistula formation. It is recommended to perform additional screening of underlying pathology or malignancy via proctoscopy, colonoscopy, or cystoscopy. When complicated by intra-abdominal abscess, priority should be taken to first drain the abscess and treat conservatively with antibiotics. Definitive treatment entails resection of the diseased sigmoid colon with takedown of the fistula (colovesical, colovaginal, colouterine, coloenteric, colocolonic) and primary repair of the hole on the involved organ. However, given the relatively short distance between the affected sigmoid colon and fistula to the proximal rectum, it is more advantageous to resect both and perform a single anastomosis.