Optimal Duration of Antibiotics Following Appendectomy for Patients With Complicated Appendicitis.

Background: Complicated appendicitis patients typically undergo appendectomy followed by antibiotics. The optimal course of antibiotics for complicated appendicitis is poorly defined.

Methods: Data were collected from patients presenting with acute appendicitis and underwent appendectomy at the index hospitalization (2015-2017). Primary outcomes were readmission rate, superficial surgical site infection (SSI), deep space infection (DSI), which includes abscess. Length of post-operative antibiotic use was recorded and an average intent-to-treat (ITT) by operative grade was calculated.

Results: Two hundred seventy-two patients (23%) were diagnosed with complicated appendicitis. SSI occurred in 4% of patients (n = 11); SSI rates ranged from 0% to 14.6% by ITT group with 3-4 days being the lowest (0%) and <3 days the highest (14.6%) ( = .008). DSI including abscesses occurred in 27 (9.9%) patients; least frequently in the 5-6 day ITT group (7.4%). Length of stay (LOS) was significantly related to longer antibiotic use ( < .001) and increasing operative grade ( < .01).

Conclusions: Given the lower incidence of postoperative complications between 3 and 6 days and no added benefit for ITT >6 days, we recommend limiting antibiotic treatment to 3-6 days for all complicated appendicitis cases with additional workup warranted if infectious symptoms persist.