An Emergency Ultrasound (EUS)-Enhanced Scoring System for Diagnosing Acute Appendicitis in Patients with Right Lower Quadrant (RLQ) Pain; Constant or Aggravated Pain, Male Sex, and Ultrasound (CAMUS) Scores

ABSTRACT

PURPOSE: We hypothesized that a new scoring system that included emergency ultrasound (EUS) and clinical or laboratory predictors for diagnosing acute appendicitis (AA) in patients with right lower quadrant (RLQ) pain could decrease the false negative rate when EUS is performed alone. METHODS: During a 10 month period, patients with RLQ pain were evaluated with EUS just after history taking and physical examination. We also checked the 17 well-known predictors of AA. Univariate analyses for each predictor including EUS findings identified 11 predictors. We then tested those predictors with logistic regression analysis. RESULTS: A total 397 patients (mean age=31.13+/-18.25 years: 196 males, 201 females) were enrolled in this study. Among the 397, 247 underwent an operation, but 14 turned out to have normal appendices. Among 233 patients with appendicitis, 75 had a perforated appendix. Four independent correlates of AA (constant pain, aggravated pain, male sex, and positive EUS findings) were identified with logistic regression analysis. We developed a novel scoring system using regression coefficients as follows: 6 points for a positive EUS, 3 points for aggravated pain, 2 points for constant pain, and 2 points for being male. We named the new scoring system "CAMUS" for "Constant or Aggravated pain, Male sex, and UltraSound score". The area under the receiver-operating characteristic curve (ROC) for the CAMUS score for AA was 0.93(95% confidence interval: 0.871 to 0.959). CONCLUSION: Our new CAMUS scoring system can help emergency physicians diagnose AA accurately and rapidly.