Diagnostic Accuracy of Modified Alvarado Score Combined with Ultrasonography and C-Reactive Protein in Suspected Acute Appendicitis: A Retrospective Study

Background: Acute appendicitis remains a common surgical emergency with risk of negative appendectomy. Early diagnosis is essential to reduce morbidity(1,3), and for that purpose clinical scoring systems such as the Modified Alvarado Score (MAS) and inflammatory markers are widely used but individual diagnostic accuracy varies specially when applied alone(2,3). The aim is to evaluate the diagnostic reliability of MAS combined with abdominal ultrasonography (USG) and C-reactive protein (CRP) levels in suspected acute appendicitis. Material and Methods: This retrospective study included 105 patients with suspected acute appendicitis. Diagnostic performance of MAS ≥7, CRP >10 mg/L, and positive USG findings and their combinations were evaluated. Histopathology served as reference standard in operated cases, while clinical follow-up confirmed non-operative cases. Sensitivity, specificity, PPV, NPV, and 95% confidence intervals were calculated. Results: Out of 105 patients, appendicitis was confirmed in 88 patients (83.8%). MAS demonstrated sensitivity of 92.0% and specificity of 82.4%. CRP demonstrated sensitivity of 83.0% and specificity of 76.5%. USG showed the highest individual accuracy with sensitivity of 94.3% and specificity of 88.2%. The strict combination model (all three positive) achieved 100% specificity, while the practical two-out-of-three model showed superior diagnostic performance with sensitivity of 98.9%, specificity of 94.1%, and accuracy of 98.1%(p<0.001). Conclusion: Combined diagnostic assessment of MAS, CRP, and USG significantly improves diagnostic accuracy. A two-parameter positive strategy provides optimal clinical utility and reduces unnecessary surgeries.

Keywords: Acute appendicitis, Modified Alvarado score, Ultrasonography, C-reactive protein, Diagnostic accuracy.