Acute appendicitis: Influence of early pain relief on the accuracy of clinical and US findings in the decision to operate - A randomized trial

PURPOSE: To determine the influence of early pain relief on the diagnostic performance of ultrasonography (US) and on the appropriateness of the surgi cal decision. MATERIALS AND METHODS: A prospective randomized, double-blind placebo-contr olled trial with morphine was conducted. A visual analog scale was used to evaluate pain in 340 patients aged 16 years or older. US was performed with a standardized protocol. Diagnosis was confirmed at histologic analysis or , in the patients released without surgery, at follow-up. RESULTS: One hundred seventy-five patients were injected with morphine, and 165 were injected with the placebo. Pain relief was stronger in the morphi ne group. In the morphine group, US had lower (71.1%)sensitivity (differenc e, -9.5%; 95% CI, -18.5%, -0.5%) and higher (65.2%) specificity (difference , 11.4%; 95% CI, 1.0%, 21.8%). This group had also a higher positive predic tive value (64.6%) and a lower negative predictive value (71.4%), but the d ifferences between this group and the placebo group were not statistically significant. Among female patients, the decision to operate was appropriate more often in the morphine group (75.8%), but the difference between this group and the placebo group was not statistically significant (5.1%; 95% CI , -7.4%, 17.6%). In male patients and overall, opiate analgesia did not inf luence the appropriateness of the decision. The appropriateness to discharg e patients without surgery was 100% in all groups. CONCLUSION: Morphine does not improve US-based diagnosis of appendicitis.