Drawing blood in vain? Reassessing routine preoperative blood cultures for acute appendicitis

Although sepsis is uncommon in acute appendicitis, emergency physicians frequently obtain preoperative blood cultures to comply with the Centers for Medicare and Medicaid Services' Sepsis and Septic Shock: Management Bundle quality measure. This practice may lead to unnecessary testing and antibiotic exposure. Data on the incidence and management of bloodstream infection in acute appendicitis remain limited. We evaluated the incidence, microbiology, and treatment patterns of preoperative bloodstream infections in patients with acute appendicitis at a large tertiary care center.

A retrospective cohort study was conducted on patients ≥16 years of age diagnosed with acute appendicitis who underwent appendectomy at an urban medical center between January 2011 and December 2023. Among patients in whom preoperative blood cultures were obtained, positive cultures were identified to determine the prevalence of bloodstream infection. Microbiologic profiles were reviewed, and postoperative antibiotic management strategies (none, oral, intravenous, or intravenous, followed by oral therapy) were analyzed using SPSS, version 24 (IBM, International Business Machines Corporation).

Of 8,241 patients with acute appendicitis, 1,741 (21.1%) had preoperative blood cultures obtained. Sixty-six cultures yielded pathogenic organisms (3.7%). The mean age of patients with bloodstream infection was 48 years; 28.7% were female. The most common isolates were Bacteroides spp. (34.8%) and Escherichia coli (22.7%). Among culture-positive patients undergoing surgery, intraoperative findings included uncomplicated appendicitis (45.4%), suppurative (3.0%), perforated (37.8%), and gangrenous (13.6%) disease. Postoperatively, 33.3% received no antibiotics, 27.2% received oral therapy, 19.7% received intravenous therapy, and 19.7% received intravenous therapy followed by oral therapy. Two patients treated with intravenous antibiotics required 30-day readmission for abscess drainage.

Bloodstream infection in acute appendicitis is rare and does not correlate with adverse outcomes in our analysis. Most cases involve expected enteric organisms and resolve with surgical source control alone. Restricting blood cultures to patients with hemodynamic instability or septic shock may promote diagnostic stewardship and reduce unnecessary antibiotic use.