EP342 - Outcomes of Intramural Abscesses in the Setting of Left-sided Diverticular Disease

Purpose/Background: A significant complication of diverticulitis is the formation of diverticular abscesses, which occur in approximately 15-20% of cases. Of these patients, around 20-30% of patients will ultimately require surgery. While most diverticular abscesses are classically described in the pericolonic region or within the pelvis, intramural abscesses are relatively rare and thus the natural history and outcomes of such are poorly understood. This study aims to evaluate the clinical course and outcomes of patients with intramural abscesses, specifically pertaining to the incidence of surgical intervention.

Methods/Interventions: We conducted a retrospective analysis of patients with intramural diverticular abscesses identified on computed tomography (CT) scans across six hospitals from January 1, 2023, to June 30, 2023. Those who had pneumoperitoneum or other abscesses present, had purulent or feculent peritonitis, or were ultimately diagnosed with colon cancer on subsequent colonoscopy or surgical pathology specimens were excluded. The primary measure of this study was colectomy-free survival. A secondary objective was to assess whether any patient-related factors affected the likelihood of requiring surgery.

Results/Outcomes: A total of 87 patient charts were individually analyzed, of which 60 met the inclusion. The mean average age of included patients was 55 years old, with females comprising 55% of the study group while 43% of patients were white. The average BMI was 29.8, and 31% of patients were smokers. The mean abscess size was 3.66 cm.

With regards to the primary outcome measure, fifteen patients (25 %) required surgical intervention. Specifically, 11 required surgery due to smoldering symptoms, 3 required surgery due to development of fistulae (two colovesical fistulae and one with colovaginal fistula), while one patient underwent surgery for a symptomatic stricture. Of the 15 patients who underwent colectomy, 13 were done robotically and 2 were done open. Nine patients had a primary anastomosis without an ostomy, 2 patients had a primary anastomosis with a proximal diverting loop ileostomy, and 4 patients had a resection with an end colostomy. Of those who had primary anastomosis, 1 developed an anastomotic leak which required operative intervention. Of the 4 patients who had a resection with end colostomy, 3 had their colostomies reversed. Both patients with diverting loop ileostomies had their ileostomies reversed.

Among the variables analyzed, including age, sex, race, BMI, smoking status, and abscess size, the only variable significantly associated with the need for surgery was abscess size, with abscesses greater than 5 cm being more likely to require surgery ( < 3 cm 16.1%; 3-5 cm 20%; > 5 cm 67%; p=0.006.) The mean time to surgery was 38 days (range 4-150 days.)

Conclusion/Discussion: This study represents the only known case series in the literature that investigated intramural diverticular abscesses. Interestingly, it was found that the clinical course of intramural abscesses closely resembled that of diverticular abscesses in general. Approximately one-quarter of patients required surgery. While abscess size was a strong predictor of surgical intervention, even abscesses smaller than 3 cm had a one-in-six likelihood of requiring colectomy.

Colectomy-free Survival According to Abscess Size