Intrathecal Morphine 75 mcg Versus 100 mcg for Post-Cesarean Analgesia: A Randomized Double-blind Trial

This prospective, randomized, double-blind controlled trial was designed to compare the analgesic efficacy and safety of two doses of intrathecal morphine (75 mcg versus 100 mcg) in patients undergoing elective cesarean delivery under spinal anesthesia. A total of 240 ASA physical status II patients schedule for elective cesarean delivery were enrolled and randomly assigned into two parallel groups. Patients received either 75 mcg or 100 mcg of intrathecal morphine as part of a standardized spinal anesthesia technique using local anesthetic. Randomization was performed using a predefined allocation method, and both patients and outcome assessors were blinded to group assignment. Perioperative management was standardized across both groups to minimize confounding variables. Postoperative pain intensity was assessed using the Visual Analog Scale (VAS) at 2, 4, 8, 12 and 24 hours following surgery. The primary outcome was VAS pain score at 24 hours. Secondary outcomes included pain scores at earlier time points, requirement for rescue analgesia, incidence of opioid-related adverse effects (nausea, vomiting, pruritus), and neonatal outcomes assessed by Apgar scores. The objetive of this study was to determinethe optimal intrathecal morphine dose that provides effective postoperative analgesia while minimizing adverse effects in the obstetric population. The study was conducted in accordance with institutional ethical standards and approved by the corresponding ethics committee.

Inclusion criteria

• Pregnant women scheduled for elective cesarean delivery under spinal anesthesia.
• Age between 18 and 45 years.
• ASA physical status II
• Singleton term pregnancy.
• Ability to provide written informed consent.

Exclusion criteria

• Contraindications to spinal anesthesia.
• Known allergy or hypersensitivity to morphine or opioids.
• Chronic opioid use or opioid dependence.
• Significant systemic disease (ASA more or equal to III).
• Pregnancy complications (e.g., preeclampsia, eclampsia).
• Body mass index more than 40 kg/m2.
• Infection at the puncture site.
• Coagulopathy or anticoagulant therapy.
• Refusal to participate.