EP109 - CT Findings of Larger Perirectal Abscesses Predict Operating Room Incision and Drainage

Image or Table (Do Not add text here):

Purpose/Background: In contrast to operative drainage, bedside incision and drainage (I&D) of anorectal abscesses in the emergency department (ED) may lead to prompt treatment and avoidance of hospital admission. However, it may be associated with increased discomfort or inadequate drainage. In a prior study, we found that bedside I&D was comparable to operative I&D for patients presenting to the ED with anorectal abscess. The objective of this follow-up study is to investigate if size of abscess on computed tomography (CT) imaging is a predictor of bedside versus operative management of perirectal abscesses.

Methods/Interventions: We conducted a retrospective observational study of patients who underwent bedside or operating room (OR) I&D of a perirectal abscess at a community teaching hospital from January 2015 to December 2023. We included patients who had a preprocedure or preoperative CT scan. Patients were identified by ICD-10 codes for perirectal abscess and the electronic medical record queried for appropriate variables. These included demographics, body mass index, systemic inflammatory response syndrome (SIRS) criteria, and greatest dimension of abscess reported on CT scan (mm). SIRS criteria were temperature > 38 or < 36 C, respiratory rate > 20, heart rate > 90, and WBC > 12 or < 4. Procedural variables included specialty, initial bedside versus operative drainage, resident involvement, and time to intervention. Patients with a history of prior abscess within one year, IBD, anorectal malignancy, NSTI, or supralevator or horseshoe abscesses were excluded. Comparisons were made using Chi squared analysis, Mann Whitney test where appropriate. Variables found to be significantly associated with procedure location were then included in a logistic regression model.

Results/Outcomes: 137 patients were included in the final analysis. Thirty five (26%) underwent OR I&D. Patients undergoing OR I&D had larger abscesses as measured by greatest dimension (46 mm vs 33 mm; p< 0.01). Univariate analysis identified greatest dimension by CT, temperature, mean arterial pressure, smoking status, and physician specialty to be associated with OR vs bedside I&D. In a logistic regression model, larger abscess size (p < 0.01), and higher temperature (p=0.03) were associated with OR I&D. Overall 30 day reintervention was statistically similar in both groups (15% bedside vs 3% OR; p=0.07). The abscess size was not associated with 30 day reintervention (29 mm for reintervention vs 36 mm for no reintervention; p=0.15).

Conclusion/Discussion: At our institution, patients with larger perirectal abscesses were more likely to undergo operative I&D as opposed to bedside I&D. There was no statistically significant difference in 30 day reintervention for the two groups. Additionally, abscess size (greatest dimension on CT) did not predict 30-day reintervention rates. Foregoing CT scan in select patients and relying on the clinical situation can improve resource utilization.