Authors: Cheng S et al.
Anesthesia & Analgesia
142(1):19–27, January 2026
Summary
This randomized, blinded noninferiority trial evaluated whether intrathecal hydromorphone provides postoperative analgesia comparable to intrathecal morphine for elective cesarean delivery. Intrathecal morphine is widely used for postcesarean analgesia but is associated with side effects and has been intermittently affected by drug shortages, prompting interest in alternatives such as hydromorphone.
A total of 126 patients undergoing elective cesarean delivery under spinal anesthesia were randomized to receive either intrathecal morphine 150 µg or intrathecal hydromorphone 75 µg, doses corresponding to the previously established ED90 for each drug. The primary endpoint was the difference in mean Numeric Rating Scale pain score over the first 24 hours postoperatively, with a predefined noninferiority margin of 1 point. Secondary outcomes included serial pain scores, cumulative opioid consumption, time to first rescue opioid, quality of recovery using the Obstetric Quality of Recovery Score-11, opioid-related side effects, and neonatal Apgar scores.
The mean 24-hour pain score was 4.0 in the morphine group and 3.6 in the hydromorphone group. The between-group difference met criteria for noninferiority, as the upper limit of the confidence interval did not exceed the predefined margin. There were no significant differences between groups in supplemental opioid use, time to first opioid request, quality-of-recovery scores, or the need for treatment of pruritus or nausea and vomiting. Neonatal outcomes were similar between groups.
The authors conclude that intrathecal hydromorphone is noninferior to intrathecal morphine for postcesarean analgesia when administered at ED90 dosing. Hydromorphone therefore represents an effective and reasonable alternative for neuraxial opioid analgesia in cesarean delivery, particularly in settings where morphine is unavailable or undesirable.
Key Points
Intrathecal hydromorphone provided postcesarean analgesia comparable to intrathecal morphine
Noninferiority criteria were met for 24-hour pain scores
Opioid consumption, side effects, and recovery quality were similar between groups
Hydromorphone may be a practical alternative during morphine shortages or intolerance
Thank you to Anesthesia & Analgesia for allowing us to summarize and discuss this clinically relevant trial in obstetric anesthesia.