Related Experiment Video
Updated: May 20, 2026
Morphometric Protocol for the Objective Assessment of Blastocyst Behavior During Vitrification and Warming Steps
Published on: February 28, 2019
Direct warming and rehydration method in frozen embryo transfer: study protocol for a pragmatic, multi-center,
Waner Wu1,2, Murong Xu1, Ka Kei Fung1
1Assisted Reproductive Technology Unit, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China.
Background:
Embryo cryopreservation through vitrification is widely used to store surplus embryos for future transfer. Traditional multi-step warming methods are both time-consuming and costly. This study evaluates the clinical outcomes and the effectiveness of a novel direct warming method for frozen embryo transfer (FET) in comparison to the conventional multi-step method.
Methods:
This is a pragmatic, two-arm, double-blinded randomized controlled trial (RCT) comparing the new direct warming method with the conventional multi-step method. Participants undergoing FET will be randomly assigned to either the direct warming method or the conventional warming protocol. The primary outcomes are the clinical pregnancy rate (CPR), ongoing pregnancy rate (OPR), the live birth rate (LBR), miscarriage rate, and cost-effectiveness. Secondary outcomes include identifying clinical differences among various brands of warming media, embryo storage devices, and embryo culture media through subgroup analyses. A sample size of 578 participants is planned, allowing for a 5% loss to follow-up.
Discussion:
Preliminary studies have shown that the direct warming method offers comparable or slightly higher live birth rates than conventional methods. Moreover, it significantly reduces thawing time and associated costs, offering a faster, cost-effective option for FET. This trial has the potential to improve accessibility to ART by reducing procedural costs and increasing efficiency without compromising clinical outcomes.
Trial Registration:
ClinicalTrials.gov NCT06741748. Registered on 19 November 2024.
