Authors: Cheng S et al.
Anesthesia & Analgesia, Volume 142, Issue 1, pages 19–27, January 2026
Summary:
This randomized, blinded noninferiority trial evaluated whether intrathecal hydromorphone is noninferior to intrathecal morphine for postcesarean delivery analgesia when both are administered at their previously established ED90 doses. Given ongoing concerns regarding morphine-related side effects and intermittent drug shortages, identifying a clinically equivalent alternative has practical importance for obstetric anesthesia practice.
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. The primary outcome was the mean Numeric Rating Scale (NRS) pain score over the first 24 postoperative hours, assessed retrospectively at 24 hours, with a noninferiority margin of 1 point. Secondary outcomes included serial pain scores, opioid consumption, time to first opioid request, quality of recovery using the ObsQoR-11, opioid-related side effects, and neonatal Apgar scores.
Mean 24-hour pain scores were slightly lower in the hydromorphone group compared with morphine, and the upper bound of the 95% confidence interval remained below the predefined noninferiority threshold, establishing noninferiority. There were no clinically or statistically significant differences between groups in postoperative opioid consumption, quality-of-recovery scores, time to first rescue opioid, or frequency of opioid-related pruritus or nausea and vomiting. Neonatal outcomes were similar between groups.
These findings confirm that intrathecal hydromorphone, at an ED90 dose of 75 µg, provides analgesia comparable to intrathecal morphine 150 µg following elective cesarean delivery, without an increase in opioid-related adverse effects.
What You Should Know:
Intrathecal hydromorphone is noninferior to morphine for postcesarean analgesia when ED90 doses are used.
Pain control, opioid consumption, and quality-of-recovery outcomes are similar between agents.
Opioid-related side effects, including pruritus and nausea, did not differ between groups.
Hydromorphone represents a viable alternative to morphine, particularly in the setting of shortages or institutional preference.
Key Points:
This randomized noninferiority trial supports intrathecal hydromorphone as an effective substitute for morphine in cesarean delivery.
Equivalent analgesia was achieved without increased opioid requirements or adverse effects.
The data support flexibility in intrathecal opioid selection for obstetric anesthesia practice.
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