The Effect of Intrathecal Morphine on Postoperative Opioid Consumption in Patients Undergoing Abdominal Surgery for Gynecologic Malignancy: A Randomized Sham-Controlled Trial

Abstract

Background: Surgery for gynecologic malignancy via midline-laparotomy leads to severe postoperative pain. Adequate pain control while sparing opioid consumption does offer benefits in postoperative complications and recovery. Intrathecal morphine (ITM) provides simple and effective analgesia. In this randomized trial, we compared postoperative opioid consumption in patients who received either ITM or a sham procedure.

Methods: We enrolled 68 adult patients undergoing open gynecologic oncology surgery from June 2021 to November 2021. They were randomly allocated to the ITM group (ITM; 200 μg injection) or sham group (sham procedure) to achieve a final 1:1 ratio between groups. We compared opioid consumption and pain severity during 72 hours after surgery. The variables regarding postoperative recovery and patient-centered outcomes were collected. The primary outcome is cumulative intravenous (IV) opioid consumption 24 hours after surgery.

Results: The median (interquartile range) cumulative IV opioid consumption during 24 hours after surgery was 18 mg (12-29) in the ITM group and 36 mg (27-42) in the sham group (median difference, 13; 95% confidence interval, 7.2-20.7; P < .001). Patient satisfaction regarding pain control was statistically significantly higher in the ITM group than in the sham group at postoperative 24 and 48 hours ( P < .001 and P = .005, respectively). There were no significant differences in the variables associated with postoperative recovery and frequency of complications requiring treatment.

Conclusions: ITM is a safe and effective analgesic method after curative intent laparotomy for gynecologic malignancy. ITM provides better pain relief, reduces opioid consumption, and improves patient satisfaction without additional evident adverse events.