Patients Undergoing Major Laparoscopic Abdominal Surgery

The goal of this clinical trial is to learn the clinical and cost effectiveness of intrathecal morphine (ITM) in addition to usual care as a postoperative pain relief strategy following major laparoscopic abdominal surgery compared with current usual care. The main questions it aims to answer are: An enhanced analgesic technique, consisting of ITM in addition to usual care , improves the postoperative quality of recovery at day 1 after surgery by at least 6 points on the 15-item quality of recovery questionnaire (QoR-15) compared to usual care alone, in patients undergoing major laparoscopic abdominal surgery? Researchers will compare ITM + Usual care to Sham ITM + Usual Care (The sham ITM mimics the ITM procedure, but the dura is not breached) to see if ITM works to postoperative pain relief. Participants will: Receive ITM + Usual care or Sham ITM + Usual care on surgery day Have interview with outcome assessors and complete the CRFs on the day of surgery, postoperative day 1, day 2, day 3 and up to postoperative day 30