Single Step Protocol and Multi-step Warming Protocol for Blastocyst FET

NCT07088640 | Recruiting DMC

• 1 other identifier: 07/25/DD-BVMD
• Study Type: interventional
• Target: 816
• Locations: 1 country
• Sites: 1

Brief Summary

The multi-step thawing protocol with a reduction of non-permeable cryoprotectant concentrations to reduce osmotic shock caused by the rapid influx of water. Recent studies have shown that a simplified warming protocol by only a thawing solution gave a comparable survival rate but increased pregnancy rate, reduced patients' waiting time, and decreased the workload of embryologists.

Conditions

IVF; Frozen Embryo Transfer (FET); Embryo Thawing Protocol

Outcome Measures

Primary Outcomes (1)

• Live birth rate

  Live birth is defined as the complete expulsion or extraction from a woman of a product of fertilization, after 22 completed weeks of gestational age; which, after such separation, breathes or shows any other evidence of life, such as heart beat, umbilical cord pulsation or definite movement of voluntary muscles, irrespective of whether the umbilical cord has been cut or the placenta is attached. A birth weight of 500 grams or more can be used if gestational age is unknown

  At 22 weeks of gestation

Secondary Outcomes (20)

• Survival rate

  At least 2 hours after thawing.

• Cancellation rate

  Any day during endometrium preparation days before embryo transfer.

• Positive pregnancy test

  At 2 weeks after embryo placement

• Implantation rate

  At 3 weeks after embryo placement

• Clinical pregnancy

  At 5 weeks after embryo placement

Study Arms (2)

Single-step thawing protocol

EXPERIMENTAL

For the warming phase, vitrified blastocysts are exposed to the thawing solution of a commercial embryo thawing kit (Irvine Scientific Inc., USA) at 37°C for one minute. Immediately following this, embryos will be rinsed through a 35mm diameter dish of 2ml of pre-equilibrated thawing solution before being placed in culture media in the incubator for at least 2 hours before transfer.

Procedure: Single-step warming protocol by thawing solution only

Multi-step thawing protocol

EXPERIMENTAL

For the Multi-step (MS) protocol, thawing kits were equilibrated overnight in a 37°C incubator. Warming procedures utilized the kits (Cryotech RtU, Japan). To remove the cryoprotectants, blastocysts were warmed, and cryoprotectants were diluted in a three-step process. The warming process starts with the exposure of blastocysts to thaw solution (TS) with 1M trehalose for one minute, set at a temperature to ensure 37°C. Subsequently, blastocysts will be transferred to a second well containing dilution solution (DS) 0.5M trehalose for a two-minute rinse at room temperature. This is followed by two additional three-minute and 30 seconds rinses in the wash solution (WS) at room temperature. The timeline for standard warming of blastocysts requires a total of 6.5 min. After thawing, embryo will be placed in the incubator at least 2 hours before transfer.

Procedure: Standard warming protocol

Interventions

Single-step warming protocol by thawing solution only PROCEDURE

Potentially eligible patients' vitrified blastocysts will be thawed by a single-step thawing protocol. For the warming phase, vitrified blastocysts are exposed to the thawing solution of a commercial embryo thawing kit (Irvine Scientific Inc., USA) at 37°C for one minute. Immediately following this, embryos will be rinsed in a 35mm diameter dish of 2ml of pre-equilibrated thawing solution before being placed in culture media in the incubator for at least 2 hours before transfer.

Also known as: Single-step thawing protocol

Single-step thawing protocol

Standard warming protocol PROCEDURE

For the MS protocol, thawing kits were equilibrated overnight in a 37°C incubator. Warming procedures utilized the kits (Cryotech RtU, Japan). To remove the cryoprotectants, blastocysts were warmed, and cryoprotectants were diluted in a three-step process. The warming process starts with the exposure of blastocysts to thaw solution (TS) with 1M trehalose for one minute at 37°C. Subsequently, the blastocyst will be transferred to a second well containing a dilution solution (DS) of 0.5M trehalose for a two-minute rinse at room temperature. This is followed by two additional three-minute and 30-second rinses in the wash solution (WS) at room temperature. The timeline for standard warming of blastocysts requires a total of 6.5 min. After thawing, embryo will be placed in the incubator at least 2 hours before transfer.

Also known as: Multi-step warming protocol

Multi-step thawing protocol

Eligibility Criteria

• Age: 18 Years+
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Women aged from 18
• Undergoing no more than 3 previous IVF/ICSI cycles
• Had at least a single good-quality blastocyst frozen.
• Endometrium preparation using artificial cycle
• Agree to single blastocyst transfer
• Not participating in any interventional studies at the same time

You may not qualify if:

• Embryos from cycles after in-vitro maturation, pre-implantation genetic testing (PGT)
• Having contraindications for exogenous hormone administration (e.g., breast cancer, thromboembolic disease)
• Having uterine abnormalities (e.g., adenomyosis, intrauterine adhesions, unicornuate/ bicornuate/ arcuate uterus; unremoved hydrosalpinx or endometrial polyp)

Sponsors & Collaborators

• Mỹ Đức Hospital: lead

Study Sites (1)

My Duc Hospital

Ho Chi Minh City, City, 7000, Vietnam

RECRUITING

Related Publications (3)

• Connolly MP, Hoorens S, Chambers GM; ESHRE Reproduction and Society Task Force. The costs and consequences of assisted reproductive technology: an economic perspective. Hum Reprod Update. 2010 Nov-Dec;16(6):603-13. doi: 10.1093/humupd/dmq013. Epub 2010 Jun 8.

  PMID: 20530804 BACKGROUND

• Seki S, Mazur P. The dominance of warming rate over cooling rate in the survival of mouse oocytes subjected to a vitrification procedure. Cryobiology. 2009 Aug;59(1):75-82. doi: 10.1016/j.cryobiol.2009.04.012. Epub 2009 May 7.

  PMID: 19427303 BACKGROUND

• Gallardo M, Saenz J, Risco R. Human oocytes and zygotes are ready for ultra-fast vitrification after 2 minutes of exposure to standard CPA solutions. Sci Rep. 2019 Nov 5;9(1):15986. doi: 10.1038/s41598-019-52014-x.

  PMID: 31690725 BACKGROUND

Study Officials

• Lan TN Vuong, MD, PhD

  University of Medicine and Pharmacy at Ho Chi Minh City

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Tam TM Luu, MD

CONTACT

+84357426024; tam.ltm@myduchospital.vn

Vu NA Ho, PhD

CONTACT

+84935843336; bsvu.hna@myduchospital.vn

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 20, 2025
• First Posted: July 28, 2025
• Study Start: August 13, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): March 1, 2027
• Last Updated: September 12, 2025

Record last verified: 2025-07

Locations

VN (1)