Antibiotic treatment after appendicectomy for complicated appendicitis aims to reduce postoperative infections. However, available data on the duration of treatment are limited. This study compared the difference in infectious complications between two protocols, involving either 3 or 5 days of postoperative antibiotic treatment.


This was an observational cohort study of all adult patients who had an appendicectomy between January 2004 and December 2010 at either one of two hospitals in the same region. At location A, the protocol included 3 days of postoperative antibiotic treatment, whereas at location B it specified 5 days. The primary outcome was the development of postoperative infections as either superficial wound infection or deep intra-abdominal infections.


A total of 1143 patients with acute appendicitis underwent appendicectomy, of whom 267 (23·4 per cent) had complicated appendicitis. The duration of postoperative antibiotic treatment was 3 days in 135 patients (50·6 per cent) and at least 5 days in 123 (46·1 per cent). No difference was found between antibiotic treatment for 3 or 5 days in terms of developing an intra-abdominal abscess (odds ratio (OR) 1·77, 95 per cent confidence interval 0·68 to 4·58; P = 0·242) or a wound infection (OR 2·74, 0·54 to 13·80; P = 0·223). In patients with complicated appendicitis, the laparoscopic approach was identified as a risk factor for developing an intra-abdominal abscess in univariable analysis (OR 2·46, 1·00 to 6·04; P = 0·049), but was not confirmed as an independent risk factor for this complication in multivariable analysis (OR 2·32, 0·75 to 7·14; P = 0·144).


After appendicectomy for complicated appendicitis, 3 days of antibiotic treatment is equally effective as 5 days in reducing postoperative infections.