Efficacy of preoperative computed tomography imaging to reduce negative appendectomies in patients undergoing surgery for left lower quadrant abdominal pain.

BACKGROUND Clinical assessment of acute appendicitis can be challenging due to atypical presentation. Computed-tomography can reduce negative appendectomies but not without adverse effects. We report our experience with preoperative CT-scan in patients with suspected acute appendicitis. PATIENTS AND METHODS During 3-years, 257 adult patients underwent appendectomy. We retrospectively reviewed clinical information, CT-scans, histological data. Patients were divided in four groups: Group I: low clinical probability without CT-scan; Group II: low clinical probability with CT-scan; Group III: high clinical probability without CT-scan; Group IV: high clinical probability with CT-scan. Negative appendectomies were determined from histological examination. Negative appendectomy rate was compared between groups of the same clinical probability differing on whether a pre-operative CT scan was performed or not (Group I vs II, Group III vs IV). RESULTS Groups I,II,III,IV included 12.4%, 18.2%, 54.5% and 14.8% of patients, respectively. The corresponding negative appendectomy rates were 18.7%, 4.3%, 4.2% and 2.6%. Odds ratio of negative appendectomy for patients without CT-scan was 5.2 (95% CI: 1.2-27.7) when there was low clinical probability and 1.6 (95% CI: 0.2-14.2) for high clinical probability. CONCLUSION Patients with low clinical probability of acute appendicitis benefit the most from preoperative CT while this does not apply to patients with high clinical probability.