The effects of preoperative intravenous acetaminophen in patients undergoing abdominal hysterectomy.

PURPOSE: Although intravenous acetaminophen is commonly used for the management of postoperative pain, very limited evidence supports the usefulness of preoperative administration. The aim of this study was to determine the analgesic effect of preoperative acetaminophen on opioid consumption, pain scores, and side effects in patients receiving an elective abdominal hysterectomy. METHODS: A randomized, double-blinded, placebo-controlled clinical trial was performed in 76 women undergoing abdominal hysterectomy. Patients received either acetaminophen 2 g (group A) or placebo (group C) intravenously 30 min before surgery under general anesthesia. Postoperative pain was treated with patient-controlled intravenous hydromorphone 0.2 mg bolus. Hydromorphone consumption, pain scores during rest and movement, and any adverse effects were recorded at 1, 2, 6, 12, and 24 h after the operation. RESULTS: Overall hydromorphone consumption was significantly lower in group A compared with group C at all the time points (P = 0.013). The total 24-h hydromorphone consumption was reduced by 30% in group A. There was no significant difference in pain scores. The incidence of postoperative nausea and vomiting after the operation were significantly lower in group A than in group C (P < 0.05). CONCLUSIONS: Premedication with acetaminophen reduced hydromorphone consumption and opioid-related side effect in patients undergoing abdominal hysterectomy, but did not significantly reduce pain intensity.