Secondary signs may improve the diagnostic accuracy of equivocal ultrasounds for suspected appendicitis in children.

Introduction: Ultrasound (US) is the preferred imaging modality for evaluating appendicitis. Our purpose was to determine if including secondary signs (SS) improve diagnostic accuracy in equivocal US studies.

Methods: Retrospective review identified 825 children presenting with concern for appendicitis and with a right lower quadrant (RLQ) US. Regression models identified which SS were associated with appendicitis. Test characteristics were demonstrated.

Results: 530 patients (64%) had equivocal US reports. Of 114 (22%) patients with equivocal US undergoing CT, those with SS were more likely to have appendicitis (48.6% vs 14.6%, p<0.001). Of 172 (32%) patients with equivocal US admitted for observation, those with SS were more likely to have appendicitis (61.0% vs 33.6%, p<0.001). SS associated with appendicitis included fluid collection (adjusted odds ratio (OR) 13.3, 95% confidence interval (CI) 2.1-82.8), hyperemia (OR=2.0, 95%CI 1.5-95.5), free fluid (OR=9.8, 95%CI 3.8-25.4), and appendicolith (OR=7.9, 95%CI 1.7-37.2). Wall thickness, bowel peristalsis, and echogenic fat were not associated with appendicitis. Equivocal US that included hyperemia, a fluid collection, or an appendicolith had 96% specificity and 88% accuracy.

Conclusion: Use of SS in RLQ US assists in the diagnostic accuracy of appendicitis. SS may guide clinicians and reduce unnecessary CT and admissions.