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Recruiting NCT07556601

Ultra-rapid Blastocyst Vitrification: Pilot Randomized Study

No phase Interventional Infertility

For patients and families

In plain language

An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.

What is being studied
The protocol lists: Standard Vitrification, Ultra-Rapid Vitrification.
Who it may be relevant to
Registry conditions: Infertility. Basic parameters: 18 years — 50 years · Female.
What needs checking
Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
Where it takes place
Spain
Next step
Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →

Unsure about the terms? Read our patient guide →

Official title

Clinical Validation of Ultra-rapid Blastocyst Vitrification: a Randomized Pilot Study in Oocyte Donation Cycles

Overview

Blastocyst vitrification is standard in assisted reproduction, but clinical data on ultra-rapid vitrification are limited. This pilot study evaluates the safety, feasibility, and preliminary clinical performance of an ultra-rapid blastocyst vitrification protocol compared with the standard approach.

Detailed description

Blastocyst cryopreservation by vitrification is currently the standard approach in assisted reproductive technology, providing high post-warming survival rates and clinical outcomes comparable to those of fresh embryo transfer. Ongoing refinements of vitrification techniques aim to further improve laboratory efficiency and workflow while maintaining biological safety and clinical effectiveness.

Ultra-rapid vitrification protocols have been developed to shorten equilibration times by modifying exposure kinetics to cryoprotectants, while preserving the fundamental biophysical principles of vitrification. Although ultra-rapid warming protocols are well established, clinical data specifically evaluating ultra-rapid vitrification of blastocysts remain limited.

Moreover, ultra-rapid vitrification requires mechanical collapse of the blastocyst before cooling, introducing an additional embryological manipulation with potential biological implications that warrant careful clinical validation. In this context, the present pilot study aims to evaluate the safety, feasibility, and preliminary clinical performance of ultra-rapid blastocyst vitrification compared with the standard vitrification protocol, prior to broader clinical implementation.

Interventions

  • Other Standard Vitrification
    1. Equilibration step: Blastocysts are equilibrated in Equilibration Solution (ES) for 10-12 minutes at room temperature. 2. Vitrification solution exposure: Blastocysts are then transferred to Vitrification Solution (VS) for a maximum exposure time of 90 seconds. 3. Loading: The blastocyst is loaded onto a Cryotop device (Kitazato). 4. Vitrification: The Cryotop is plunged directly into liquid nitrogen within 1 second of loading to ensure ultra-rapid cooling. 5. Capping: The Cryotop is immediat
  • Other Ultra-Rapid Vitrification
    The ultra-rapid vitrification protocol is identical to the standard protocol in terms of media, devices, and laboratory conditions, with the following modifications: Preparation step - Blastocyst shrinkage: Prior to equilibration, artificial collapse of the blastocyst is performed using a single laser pulse to induce blastocoel shrinkage. The subsequent steps are: 1. Equilibration step: Blastocysts are equilibrated in Equilibration Solution (ES) for 2-4 minutes. 2. Vitrification solution expo

Primary outcome measures

  • Post-warming survival rate [Time frame: Immediately after warming (within the same laboratory session)]
  • Clinical pregnancy rate per transfer (only first transfer will be considered). [Time frame: 6-8 weeks after embryo transfer]
Secondary outcome measures (4)
  • Blastocyst re-expansion [Time frame: Within 2 hours after warming]
  • Post-warming blastocyst morphokinetic parameters [Time frame: From embryo warming until embryo transfer (within 2-6 hours post-warming)]
  • Post-warming blastocyst morphological quality [Time frame: From embryo warming until embryo transfer (within 2-6 hours post-warming)]
  • Technical or embryological adverse events. [Time frame: From blastocyst warming until embryo transfer, within the same clinical procedure (up to 6 hours post-warming)]

Eligibility criteria

Inclusion criteria

  • Recipients of donor oocytes
  • Blastocysts suitable for cryopreservation

Exclusion criteria

  • Cycles involving PGT
  • Cycles not reaching blastocyst stage.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation
Randomized
Model
Parallel assignment
Masking
Open label
Primary purpose
Treatment

Study locations

Spain · 2 centers
  • Hospital Universitario Quiron Dexeus — Barcelona
  • Hospital Universitario Quiron Dexeus — Barcelona

Publications

  • Boyard J, Reignier A, Chtourou S, Lefebvre T, Barriere P, Freour T. Should artificial shrinkage be performed prior to blastocyst vitrification? A systematic review of the literature and meta-analysis. Hum Fertil (Camb). 2022 Feb;25(1):24-32. doi: 10.1080/14647273.2019.1701205. Epub 2020 Jan 24. PMID 31973647
  • George JS, Keefe KW. Freezer burn or learning curve? Prolonged time since blastocyst vitrification and impact on pregnancy outcomes. Fertil Steril. 2023 Jan;119(1):45-46. doi: 10.1016/j.fertnstert.2022.11.017. Epub 2022 Nov 19. No abstract available. PMID 36410446
  • Gunst J, Joris H, Vynck M, Godderis K, Vercammen M, Roggeman S, van de Vijver A. Validation and clinical study of single-step vitrification combined with single-step warming of human blastocysts. J Assist Reprod Genet. 2026 Mar;43(3):837-850. doi: 10.1007/s10815-025-03790-1. Epub 2026 Feb 13. PMID 41686351
  • Kovacic B, Taborin M, Vlaisavljevic V, Reljic M, Knez J. To collapse or not to collapse blastocysts before vitrification? A matched case-control study on single vitrified-warmed blastocyst transfers. Reprod Biomed Online. 2022 Oct;45(4):669-678. doi: 10.1016/j.rbmo.2022.03.030. Epub 2022 Apr 10. PMID 35963753
  • Li Z, Wang YA, Ledger W, Edgar DH, Sullivan EA. Clinical outcomes following cryopreservation of blastocysts by vitrification or slow freezing: a population-based cohort study. Hum Reprod. 2014 Dec;29(12):2794-801. doi: 10.1093/humrep/deu246. Epub 2014 Oct 14. PMID 25316444
  • Martinez-Rodero I, Gallardo M, Pisaturo V, Scarica C, Conaghan J, Liebermann J, Cuevas-Saiz I. Shorter protocols for vitrification and post-warming dilution of human oocytes and embryos: a narrative review. Reprod Biomed Online. 2025 Aug;51(2):104857. doi: 10.1016/j.rbmo.2025.104857. Epub 2025 Feb 7. PMID 40479947
  • Perez-Sanchez M, Pardinas ML, Diez-Juan A, Quinonero A, Dominguez F, Martin A, Vidal C, Beltran D, Mifsud A, Mercader A, Pellicer A, Cobo A, de Los Santos MJ. The effect of vitrification on blastocyst mitochondrial DNA dynamics and gene expression profiles. J Assist Reprod Genet. 2023 Nov;40(11):2577-2589. doi: 10.1007/s10815-023-02952-3. Epub 2023 Oct 6. PMID 37801195
  • Rienzi L, Gracia C, Maggiulli R, LaBarbera AR, Kaser DJ, Ubaldi FM, Vanderpoel S, Racowsky C. Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance. Hum Reprod Update. 2017 Mar 1;23(2):139-155. doi: 10.1093/humupd/dmw038. PMID 27827818

Identifiers

NCT: NCT07556601 · FSD-UFV-2026-04

Primary sources (government registries)

View this study on ClinicalTrials.gov ↗