INFLUENCE OF ULTRASOUND ON CLINICAL DECISION-MAKING IN ACUTE APPENDICITIS - A PROSPECTIVE-STUDY

Objective: To assess the efficacy of ultrasound (US) as part of an alg orithm to establish the indication for laparotomy in patients with sus pected acute appendicitis. Design: Prospective investigation. Setting: University department of surgery, Germany. Subjects: 669 unselected p atients admitted with suspected acute appendicitis. Interventions: Cli nicopathological and procedural diagnoses of the algorithm were evalua ted by correlating clinical and US findings with the results of laparo tomy in 171 patients of whom 143 had acute appendicitis (prevalence 21 %), and clinical as well as follow up data in the remainder. Main outc ome measures: The major clinicopathological variables were accuracy an d positive predictive value; the rate of negative laparotomies and tha t of bad diagnostic errors served as the main procedural variables. Re sults: The overall sensitivity, specificity, and accuracy of the clini cal diagnosis were 0.503, 0.950, and 0.855, respectively (positive pre dictive value: PPV 0.734, negative predictive value: NPV 0.875), those of ultrasound: 0.797, 0.967, and 0.931 (PPV 0.870, NPV 0.946); and 0. 853, 0.927, and 0.940 at the end of the algorithm (PPV 0.762, NPV 0.95 8). However, the algorithm would have resulted in a significant increa se in the rate of unnecessary laparotomies (from 13% to 16%). A revise d clinical algorithm gave an overall diagnostic accuracy of 0.940 (p < 0.001) together with a low rate of negative laparotomies (11%, p < 0. 01) and a significantly reduced number of diagnostic errors (from 71 t o 21, p < 0.001). Conclusion: Ultrasonography enabled us to diagnose a cute appendicitis in more patients more often and more quickly than cl inical evaluation alone, suggesting that US may produce a better outco me. The revised clinical algorithm may be helpful in the study of US i n patients with suspected acute appendicitis in prospective randomised controlled clinical trials.