摘要Background Abdominal pain is a common symptom among patients with acute appendicitis, yet these patients havelong been denied relief from suffering because of widespread misconceptions associated with the use of opioids. Wedetermined whether morphine hydrochloride masked the physical signs in adults with acute appendicitis and assessedthe efficacy of morphine in relieving abdominal pain.Methods A prospective, double-blind, placebo controlled, clinical trial was conducted with 106 adult patients between16 and 70 years old with acute appendicitis. Patients were randomly divided into a morphine group (n=54) or a normalsaline group (n=52). All patients presented with acute abdominal pain with onset within 3 days. The morphine groupreceived hypodermic injection of morphine (0.15 mg/kg; maximum 20 mg) and the control group members were given anequivalent volume of normal saline solution. The clinical symptoms, physical signs, and patients' cooperation duringphysical examination were assessed before and after 30 minutes of morphine or normal saline administration.Results Abdominal pain was significantly relieved and the patients' cooperation was improved in the morphine groupafter 30 minutes treatment compared with the control group and before morphine administration (P<0.05). The physicalsigns were unaffected by either treatment (P>0.05).Conclusions Morphine relieved abdominal pain and improved the patients' cooperation for treatment and care.Furthermore, the morphine did not mask the physical signs of acute appendicitis.