Background: Morphine is frequently added to spinal anaesthesia for Caesarean delivery. We aimed to determine whetherintrathecal morphine for spinal anaesthesia decreases the risk of chronic...Show moreBackground: Morphine is frequently added to spinal anaesthesia for Caesarean delivery. We aimed to determine whetherintrathecal morphine for spinal anaesthesia decreases the risk of chronic postsurgical pain (CPSP).Methods: In this randomised, double-blind, placebo-controlled trial, 290 healthy parturients undergoing electiveCaesarean delivery were randomly assigned in a 1:1 ratio to receive either intrathecal morphine 100 mg (n145) or normalsaline (control; n145) as a part of spinal anaesthesia. Anaesthetic care and postoperative pain management werestandardised in all patients. The primary outcome was the incidence of CPSP at 3 months. Secondary outcomes includedCPSP at 6 months, pain severity, and pain interference, measured by the Brief Pain Inventory questionnaire using an 11-point numeric rating scale, at 3 and 6 months after the surgery.Results: Two hundred and seventy-six patients completed the 3-month follow-up, 139 in the morphine group and 137 inthe placebo group. The incidences of CPSP at 3 months were 19% (27 of 139) in the morphine group and 18% (25 of 137) inthe placebo group (odds ratio, 1.08; 95% confidence interval, 0.59e1.97; P0.803). At 6 months, CPSP was present in 23 of139 (16%) morphine group patients compared with 19 of 137 (14%) in the placebo group (odds ratio, 1.23; 95% confidenceinterval, 0.63e2.38; P0.536). Brief Pain Inventory questionnaire scores for pain severity and pain interference at 3 and 6months were similar between groups.Conclusions: Administration of morphine 100 mg as a component of spinal anaesthesia for elective Caesarean deliveryfailed to reduce the incidence of chronic pain at 3 and 6 months after surgery.Show less