J. Sincavage1,2, C. Buonpane1,2, B. Benyamen2, E. Benya2, T. Lautz1,2, C. J. Hunter1,2 1Feinberg School Of Medicine – Northwestern University,Surgery,Chicago, IL, USA 2Ann & Robert H. Lurie Children’s Hospital of Chicago,Pediatric Surgery,Chicago, IL, USA
Introduction: The clinical presentation of appendicitis is variable, and radiologic imaging is often used to help make the diagnosis. The accuracy of magnetic resonance imaging (MR) for the diagnosis of appendicitis has been validated and has replaced computed tomography (CT) in some centers, particularly in the setting of a non-diagnostic ultrasound (US). Nonetheless, MR is not widely used in this setting due to high cost, variability of MR capacity among institutions, time required for the study, and high rates of negative scans. Clinical scoring systems such as the Alvarado Score (AS) have been used to aid in the diagnosis of appendicitis but have limited efficacy when used in isolation. We hypothesized that the AS could predict patients in which an MR would be diagnostic of appendicitis.
Methods: This study is a single institution, retrospective review of patients ≤18 years of age who received US in the workup of suspected appendicitis in 2017 at a tertiary care children’s hospital with 24-hour MR capabilities. Non-diagnostic US studies were defined as non-visualization of the appendix or inability to rule out appendicitis. Imaging results were reviewed and AS were calculated from data obtained in patient EMR notes. Primary outcome was a confirmed pathologic diagnosis of appendicitis.
Results: 408 patients met inclusion criteria, of whom 60.5% had a non-diagnostic US. 48% percent of patients then received MR for further evaluation, of which 72% were negative for appendicitis. Of the patients who had a non-diagnostic US, MR, and data available for AS calculation, 20 were low score (0-3), 51 moderate score (4-6) and 30 high score (7-10). High AS patients were five times more likely to undergo appendectomy than low/moderate AS patients (OR 5.3, 95% CI 2.1-13.5, p=0.0004). Patients with low/moderate AS had a higher rate of negative MR after US than patients with high AS (82.5% versus 41.4%, p = 0.0001). The number of MRs needed to identify one case of appendicitis in the high AS group was 1.75, 5.5 in the moderate AS group, and 6 in the low AS group.
Conclusion: MR after non-diagnostic US in the workup of suspected appendicitis has increased diagnostic value in patients with high AS. Based on our results, we believe that the AS can assist health care providers in determining the additional utility of MR in the workup of appendicitis. In order to optimize usage of MR at institutions with access to this imaging modality, we do not recommend MR in the setting of low/moderate AS.