Cesarean section is one of the most commonly performed surgical procedures worldwide, making effective management of acute postoperative pain a key issue in obstetric anesthesiology. Post-cesarean analgesia should promote rapid maternal recovery, support newborn care, and consider the pharmacological implications for breastfeeding.

According to recent PROSPECT® guidelines from ESRA, neuraxial opioids play a central role in post-cesarean analgesia and are at least as effective as other techniques, such as continuous local anesthetic infusion. However, the optimal route of opioid administration remains unclear. While earlier studies favored epidural morphine, more recent evidence suggests that intrathecal morphine may provide superior analgesia. Due to limited and conflicting data, no definitive conclusion can be drawn. Given that epidural morphine remains standard practice at Hospital Central do Funchal, a randomized clinical trial is proposed to compare the analgesic efficacy of intrathecal versus epidural morphine after elective cesarean section.

This unicentric randomized clinical trial aims to determine whether intrathecal morphine provides superior postoperative analgesia compared with epidural morphine during the first 24 hours following cesarean section. The study population will consist of pregnant women undergoing elective cesarean delivery at Hospital Central do Funchal.

Participants will be randomly assigned to one of two groups. One group will receive postoperative analgesia with intrathecal morphine (80 mcg). The second group will receive epidural morphine, administered as a 2.5 mg bolus at the end of surgery, followed by an additional 2.5 mg bolus 24 hours postoperatively.

The primary outcome will be the assessment of pain during the first 24 postoperative hours. Secondary outcomes will include pain assessment during the first 48 hours, the need for rescue analgesia, levels of sedation, incidence of nausea and vomiting, pruritus, the impact of pain on mobilization and other activities, and overall maternal satisfaction.

Inclusion Criteria:

• Pregnant women scheduled for elective cesarean section;
• Age > 18 years;
• Willingness to participate in the study, as demonstrated by signed informed consent.

Exclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status classification > III;
• Chronic kidney disease with a glomerular filtration rate < 60 mL/min;
• Relevant drug allergies (particularly to protocol medications);
• Opioid tolerance;
• Contraindication to neuraxial anesthetic techniques.