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.