The Time Course of Perforation and Abscess Formation in Appendicitis

Background Many studies have supported delayed appendectomy because the risk of perforation does not appear to increase until beyond 24–48 h of hospitalization. This study aimed to examine the natural time progression of perforation in acute appendicitis to find if it complements studies that recommend delayed appendectomy. Methods Between first of January 2018 and 30th of March 2020, 1274 patients, 40 years or younger, were suspected of appendicitis at the National University Hospital of Iceland. N = 658 of these had appendicitis of which 105 did perforate. The patients' medical records were examined for duration of symptoms and length of hospital stay, whereas perforation and abscess formation were assessed from CT, ultrasounds, surgical reports, and histopathology reports. Duration of symptoms and hospital stay were categorized, and their relationship with the other variables, primarily perforation, was analyzed with chi square, Spearman's correlation, and t ‐test statistics. Results Few perforations occurred during the first 24 h of symptoms (2.4%) and few abscesses before 48 h (1.7%). Thereafter, the rate of perforations relative to the rate at 0–24 h were 6.4, 14.7, 20.2, and 27.1 for 24–48, 48–72, 72–96, and 96+ hours respectively, ( χ 2 = 120 and p < 0.001). Furthermore, there was a significant correlation between increased duration of symptoms and prolonged hospital stay in patients with appendicitis (rho = 0.36 and p < 0.001). Conclusions There was a clear correlation between the duration of symptoms and the incidence of perforated appendicitis. However, there was not a sharp increase in perforation and abscess formation until after 24 and 48 h of symptoms, respectively. Our study indicates that delayed appendectomy needs more careful evaluation after this time window has elapsed, focusing exclusively on the time since hospitalization would be insufficient.