Oxytocin Bolus Versus Infusion in High-Risk Patients Undergoing Elective Cesarean Section (INBOX-HR)

What Was Tested

In this phase 4 trial, researchers set out to test Oxytocin.

The main questions that will be answered are: 1.

It had two arms (groups): Oxytocin Bolus (active comparator) and Oxytocin Infusion (active comparator).

The registry classes the interventions as drug.

More on the Plan

However, the optimal strategy for oxytocin administration remains controversial.

Which makes the most logical next question: Does bolus oxytocin become more clinically meaningful in patients with higher baseline risk for uterine atony or hemorrhage.

The investigators aim to address this question with the INBOX-HR study.

INBOX-HR acts as a continuing investigation on the difference between bolus versus infusion administration of oxytocin, specifically for patients that are at a high risk for postpartum hemorrhage.

Who Took Part

Enrollment: 180 planned participants were the target.

It was open to women only aged from 18 years up to 45 years.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: Undergoing elective cesarean section under spinal anesthesia or combined spinal anesthesia (CSE). Patients must be able to provide written informed consent in either English or Spanish. Parturient classified as high risk for postpartum hemorrhage as defined by the adapted California Maternal Quality Care Obstetric Hemorrhage Risk Screen.

The full record lists 3 inclusion and 9 exclusion criteria; among the exclusions: parturient in labor or ruptured membranes; patient does not possess the physical and mental capacity to provide informed consent; urgent or emergent cesarean sections.

How the Study Was Run

It was run as a randomized, parallel-group and triple-blind study.

Random assignment meant chance, not the researchers, decided who got Oxytocin and who got the comparison, which limits bias.

Groups ran in parallel: each of the participants stayed in one arm throughout.

As a double-blind Oxytocin study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant, care provider and investigator.

It started in 2026-08 with completion listed for 2028-08.

Its stated primary purpose is other.

What Was Measured

The main thing measured (primary outcome): Time to uterine tone (time frame: 2 minutes after umbilical cord clamp until 10 minutes).

It also tracked 8 secondary outcomes, for example Estimated intraoperative blood loss, Changes in heart rate (beats per minute), Changes in blood pressure (mmHg), Participants with need for additional uterotonic agents, 0-10 Uterine tone score and Participants with maternal side effects.

What This Means in Plain Language

Put simply, this is a phase 4, randomized trial of Oxytocin in 180 people.

Its status is not yet recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Oxytocin compound page, all human trials.