Risk factors for developing intra-abdominal abscess following appendicectomy for acute appendicitis: a retrospective cohort study.

Background: Laparoscopic appendicectomy is commonly performed in Australia for treatment of acute appendicitis. Intra-abdominal abscess (IAA) is a potential complication following appendicectomy for acute appendicitis. Risk factors for developing post-operative IAA remain controversial and poorly defined. Laparoscopic washout may be performed for patients who develop complication(s) including IAA. The aim of this study was to define risk factors for both the development of IAA and identify patients who may require laparoscopic washout following appendicectomy.

Methods: Data were obtained from 423 patients who underwent laparoscopic appendicectomy over a five-year period (2012-2017). Clinical (fever, haemodynamics, examination findings), biochemical (white cell count, neutrophil count, C-reactive protein, bilirubin, albumin), radiological (CT free fluid), and operative factors (inflammation, suppuration, free-fluid, perforation, histopathology) collected in the pre-, peri-, and post-operative period(s) were analysed.

Results: 23 (5.4%) patients developed post-operative IAA. Duration of intravenous antibiotics was significantly longer in patients who developed IAA and in those who required laparoscopic washout (p < 0.0001). C-reactive protein (CRP) on admission (p < 0.05) and appendiceal perforation (p = 0.0005) were significantly higher in patients who either developed IAA or needed laparoscopic washout. No clinical or radiological finding predicted either the development of IAA or need for laparoscopic washout.

Conclusion: Elevated CRP on admission may predict the development of post-operative IAA formation or the need for laparoscopic washout post-appendicectomy. Prolonged post-operative antibiotic use appears independent of the development of IAA as well as the need for laparoscopic washout. These data highlight the need for clear guidelines on peri-operative antibiotic use following appendicectomy.