A Comparison Between 0.1 and 0.2 mg of Intrathecal Morphine for Caesarean Section on Postoperative Pruritus in Phaholpolpayuhasena Hospital: A randomized, double-blinded, controlled trial

Abstract

Objective: To compare the incidence of pruritus, nausea and vomiting, and pain scores between groups receiving 0.1 mg and 0.2 mg intrathecal morphine in pregnant women undergoing cesarean section under spinal anesthesia at Phaholpolpayuhasena Hospital.

Methods: This was a prospective, double-blinded, randomized controlled trial conducted on pregnant women undergoing non-emergency cesarean section under spinal anesthesia at Phaholpolpayuhasena Hospital between February and April 2025. A total of 72 participants were randomly allocated into two groups of 36 each using block randomization. The incidence of pruritus, nausea and vomiting, and average pain scores were compared at time intervals of 0–2, 2–12, and 12–24 hours post-administration. Data were analyzed using the   chi-square test and independent t-test,

Results: The incidence of pruritus showed no significant difference between groups at all time intervals (2.78, 52.78, 30.56% vs 11.11, 69.44, 38.89%, respectively), although a decreasing trend was observed in the 0.1 mg group. Nausea and vomiting incidence at 0–2 and 2–12 hours did not differ between the groups. However, during the 12–24-hour period, the 0.1 mg group had a significantly lower incidence of nausea and vomiting (0 vs 13.89%; p=0.020). The average pain scores and analgesic use did not differ between the groups.

Conclusion: Reducing the intrathecal morphine dose to 0.1 mg did not significantly reduce pruritus but clearly decreased nausea and vomiting during the 12–24hour period, without compromising pain control. Therefore, a lower dose may help minimize side effects while maintaining analgesic efficacy.