Prophylactic Intravenous Ondansetron versus Metoclopramide for Preventing Spinal Anesthesia-Induced Hypotension and Nausea during Cesarean Section

International Journal of Obstetrics and Gynecology | Vol. 14, No. 8, August 2026 | pp. 361–372

DOI: 10.46882/2026/IJOG/000507

Original Research Article

Title: Prophylactic Intravenous Ondansetron versus Metoclopramide for Preventing Spinal Anesthesia-Induced Hypotension and Nausea during Cesarean Section

Names of Authors: Emeka J. Obi¹, Funmilayo R. Adeyemi², Zainab H. Dogara¹

Authors’ Affiliations:
¹ Department of Obstetrics and Gynecology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria
² Maternal Health Division, Federal Ministry of Health, Abuja, Nigeria

Abstract:
Spinal anesthesia for cesarean section routinely induces maternal hypotension and intraoperative nausea due to sympathetic blockade. This double-blind randomized controlled trial compared the clinical efficacy of prophylactic intravenous ondansetron versus metoclopramide in mitigating spinal-induced hypotension and emetic symptoms. Two hundred and forty healthy parturients scheduled for elective cesarean birth were randomized into two equal groups (n = 120 per group). Group A received 4 mg of intravenous ondansetron, while Group B received 10 mg of intravenous metoclopramide 5 minutes before the initiation of spinal anesthesia. Vital signs were checked at 2-minute intervals during the first 20 minutes following spinal injection. The primary outcome was the incidence of maternal hypotension (systolic blood pressure < 90 mmHg or a drop > 20% from baseline). The incidence of spinal anesthesia-induced hypotension was significantly lower in the ondansetron group compared to the metoclopramide group (31.7% vs. 52.5%, p = 0.001). Consequently, the total requirement for rescue phenylephrine doses was reduced in the ondansetron arm (1.4 ± 0.5 mg vs. 2.6 ± 0.8 mg, p < 0.001). Ondansetron also provided superior protection against intraoperative nausea and vomiting (5.8% vs. 17.5%, p = 0.004). Neonatal Apgar scores and umbilical cord blood gas parameters were excellent and comparable across both cohorts (p > 0.05). Prophylactic administration of 4 mg intravenous ondansetron minimizes the incidence and severity of maternal hypotension and intraoperative nausea, stabilizing cardiovascular hemodynamics during cesarean delivery under spinal anesthesia.

Keywords: Spinal Anesthesia; Cesarean Section; Hypotension; Ondansetron; Metoclopramide; Vasopressor Requirement.

Manuscript Timeline: Received: May 25, 2026; Revised: July 15, 2026; Accepted: August 04, 2026; Published: August 18, 2026.

Citation: Obi EJ, Adeyemi FR, Dogara ZH. Prophylactic Intravenous Ondansetron versus Metoclopramide for Preventing Spinal Anesthesia-Induced Hypotension and Nausea during Cesarean Section. International Journal of Obstetrics and Gynecology. 2026; 14(8): 361–372.

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