Optimal Duration of Antibiotics Following Appendectomy for Patients With Complicated Appendicitis

Am Surg. 2021 Mar;87(3):480-485. doi: 10.1177/0003134820947372. Epub 2020 Oct 13.


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%) (P = .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 (P < .001) and increasing operative grade (P < .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.

Keywords: antibiotic duration; complicated appendicitis; deep space infection; readmission rate.

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / administration & dosage*
  • Anti-Bacterial Agents / therapeutic use
  • Appendectomy*
  • Appendicitis / surgery*
  • Drug Administration Schedule
  • Female
  • Humans
  • Male
  • Middle Aged
  • Postoperative Care / methods*
  • Retrospective Studies
  • Surgical Wound Infection / epidemiology
  • Surgical Wound Infection / prevention & control*
  • Treatment Outcome


  • Anti-Bacterial Agents