A comparison of ketorolac and fentanyl for controlling postoperative uterine cramping pain in ambulatory surgery patients

Abstract

Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce the pain of dysmenorrhea by inhibiting the synthesis of prostaglandins that cause the uterus to contract. Studies have not been undertaken previously to determine the effectiveness of NSAIDs in controlling uterine pain resulting from gynecological surgery. This study compares the NSAID ketorolac tromethamine to fentanyl, a commonly used opioid, in 100 women undergoing gynecological surgery in an ambulatory setting. Subjects were randomly assigned to receive either fentanyl or ketorolac IM at the end of the surgical procedure. Uterine cramp pain and non-uterine pain were rated on separate verbal analog scales in the recovery room. Incidence of nausea and vomiting and need for postoperative opioid analgesics were also compared between the two study groups. No significant differences were found between the two groups in the severity of uterine cramp pain, in the need for supplemental analgesia or in the incidence of nausea or vomiting. Both drugs appeared to provide reasonable patient comfort, but in the sub-group of patients who required postoperative opioid, the ketorolac group had lower non-uterine pain scores in the late postoperative period than did the fentanyl group. The absence of clear superiority of the NSAID may indicate that a biochemical pathway other than the prostaglandin mechanism is involved in the production of postoperative uterine cramping pain.