Clinical scores (Alvarado and AIR scores) versus imaging (ultrasound and CT scan) in the diagnosis of equivocal cases of acute appendicitis: a randomized controlled study

Abstract

Introduction About 50% of acute appendicitis cases are atypical in their presentation. The objectives of this study was to assess and compare the feasibility of clinical scores [Alvarado and Appendicitis Inflammatory Response (AIR)] and imaging [ultrasound and abdominopelvic computed tomography (CT) scan] in the evaluation of equivocal cases of acute appendicitis in a clinical trial to identify that subset of patients who really need and will benefit from imaging, mainly CT scan. Methods: A total of 286 consecutive adult patients with suspected acute appendicitis were included. The clinical scores, including Alvarado and AIR scores and ultrasound, were done for all patients. Abdominal and pelvic CT scans were done for 192 patients to resolve the diagnosis of acute appendicitis. The sensitivity, specificity, positive and negative predictive values, and accuracy rate of both clinical scores and imaging (ultrasound and CT scan) were compared. The final histopathology was used as the gold standard for which the diagnostic feasibility of the clinical score and imaging were compared. Results: Out of 286 total patients who presented with right lower quadrant abdominal pain, a presumptive diagnosis of acute appendicitis was made in 211 patients (123 males and 88 females) after thorough clinical evaluation, clinical scores, and imaging, and they were submitted to appendicectomy. The overall prevalence of acute appendicitis proved by histopathology as a gold standard was 89.1% (188 patients) with a negative appendectomy rate of 10.9%. Simple acute appendicitis was reported in 165 (78.2%) patients and perforated appendicitis in 23 (10.9%) patients. For patients with equivocal clinical scores (≥ 4 to ≤ 6), the sensitivity, specificity, predictive values, and accuracy rate of CT scan were significantly higher than those of Alvarado and AIR scores. Patients with low clinical scores (≤ 4) and high clinical scores (≥ 7), the sensitivity, specificity, predictive values, and accuracy rate of clinical scores and imaging were comparable. The diagnostic feasibility of AIR scores was significantly higher than the Alvarado score, and the clinical scores were associated with significantly higher diagnostic accuracy than ultrasound. CT scan is unlikely to be needed and will add little to the diagnosis of acute appendicitis for patients with high clinical scores (≥ 7). The sensitivity of the CT scan for perforated appendicitis was lower than that for nonperforated appendicitis. The use of CT scans for query cases did not change the negative appendectomy rate. Conclusion: CT scan evaluation is beneficial only for patients with equivocal clinical scores. For patients with high clinical scores, surgery is recommended. AIR score was superior to the Alvarado score in terms of sensitivity, specificity, and predictive values. A CT scan is usually not required for patients with low scores since acute appendicitis is unlikely; in such cases, ultrasound could be of help to exclude other diagnoses.