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

Radiology. 1999 Mar;210(3):639-43. doi: 10.1148/radiology.210.3.r99fe54639.


Purpose: To determine the influence of early pain relief on the diagnostic performance of ultrasonography (US) and on the appropriateness of the surgical decision.

Materials and methods: A prospective randomized, double-blind placebo-controlled 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 morphine group. In the morphine group, US had lower (71.1%) sensitivity (difference, -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 predictive value (64.6%) and a lower negative predictive value (71.4%), but the differences 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 influence the appropriateness of the decision. The appropriateness to discharge patients without surgery was 100% in all groups.

Conclusion: Morphine does not improve US-based diagnosis of appendicitis.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Abdominal Pain / drug therapy*
  • Acute Disease
  • Adolescent
  • Adult
  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / therapeutic use
  • Appendectomy*
  • Appendicitis / diagnostic imaging*
  • Appendicitis / surgery
  • Confidence Intervals
  • Decision Making*
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Humans
  • Injections, Intravenous
  • Male
  • Morphine / administration & dosage
  • Morphine / therapeutic use
  • Pain Measurement
  • Patient Discharge
  • Placebos
  • Predictive Value of Tests
  • Prospective Studies
  • Sensitivity and Specificity
  • Sex Factors
  • Ultrasonography


  • Analgesics, Opioid
  • Placebos
  • Morphine