PurposeDiverticulitis of vermiform appendix is known as a rare cause of acute appendicitis, most of which are diagnosed after surgery. We compared appendiceal diverticulitis with acute appendicitis to study the clinical characteristics of appendiceal diverticulitis.MethodsAmong 1,029 patients who received appendectomy from January 2009 to May 2011, 38 patients with appendiceal diverticulitis (diverticulitis group) were compared with 98 randomly collected patients with acute appendicitis (appendicitis group) during the same period. Patients' characteristics, clinical features, laboratory findings, operative findings, and postoperative course were compared between the two groups.ResultsThirty-eight patients (3.7%) were pathologically diagnosed with acute appendiceal diverticulitis among 1,029 cases of appendectomy. The mean age of patients in the diverticulitis group was significantly older than that of the appendicitis group (49.0 ± 15.2 years vs. 25.4 ± 14.2 years, P < 0.05). Mean duration of preoperative symptoms was longer in the diverticulitis group (3.6 ± 3.8 days vs. 1.8 ± 3.2 days, P < 0.05). The site of abdominal pain, fever, signs of localized peritonitis, accompanying gastrointestinal symptoms, and white blood cell count showed no differences between the two groups. Twenty-five patients (65.8%) of the diverticulitis group and 10 patients (10.2%) of the appendicitis group showed perforation of appendix (P < 0.05). Mean operating time and postoperative hospital stay were longer in the diverticulitis group (55.3 ± 28.8 minutes vs. 41.4 ± 17.8 minutes, 6.8 ± 3.4 days vs. 4.9 ± 1.5 days, P < 0.05).ConclusionAcute diverticulitis of the appendix can be classified into quite different disease entities compared with acute appendicitis. Regarding high rates of perforation, immediate surgical treatment is needed for patients with a high index of suspicion of acute diverticulitis of the appendix.