Ultra-rapid Blastocyst Vitrification: Pilot Randomized Study
ConditionInfertility
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexFemale
Age18-50
SponsorFundacion Dexeus
About this trial
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.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Recipients of donor oocytes
Blastocysts suitable for cryopreservation
Disqualifiers
Cycles involving PGT
Cycles not reaching blastocyst stage.
Trial design
Design model
Parallel
Treatments tested in this trial
Standard Vitrification
Other intervention1. 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 immediately capped under liquid nitrogen conditions.
Ultra-Rapid Vitrification
Other interventionThe 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 exposure: Transfer to Vitrification Solution (VS) for a maximum of 90 seconds. 3. Loading: Loading of the blastocyst onto a Cryotop device. 4. Vitrification: Immediate plunging of the Cryotop into liquid nitrogen within 1 second. 5. Capping: Immediate capping under liquid nitrogen.
Treatment groups
80 Participants
are divided into 2 treatment groupsGroup A: Standard Vitrification ProtocolActive comparator 1 intervention
Group B: Ultra-Rapid Vitrification ProtocolExperimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Post-warming survival rate
the proportion of vitrified blastocysts that remain morphologically viable after warming, expressed as a percentage of all warmed blastocysts.
Time frame
Immediately after warming (within the same laboratory session)2
Clinical pregnancy rate per transfer (only first transfer will be considered).
defined as the proportion of embryo transfers resulting in a clinical pregnancy, confirmed by the presence of an intrauterine gestational sac on ultrasound. Only the first embryo transfer per patient is included in the analysis.
Time frame
6-8 weeks after embryo transferSecondary outcomes
1
Blastocyst re-expansion
defined as the resumption of blastocoel expansion after warming, as assessed by partial or complete reformation of the blastocyst cavity, indicating post-warming viability
Time frame
Within 2 hours after warming2
Post-warming blastocyst morphokinetic parameters
Assessment of post-warming embryo developmental dynamics based on time-lapse observation. Morphokinetic parameters will include time to blastocoel re-expansion and time to resumption of blastocyst development, measured in hours from warming to embryo transfer.
Time frame
From embryo warming until embryo transfer (within 2-6 hours post-warming)3
Post-warming blastocyst morphological quality
Evaluation of blastocyst morphological quality after warming and prior to embryo transfer. Blastocysts will be graded according to standard morphological criteria based on blastocoel expansion, inner cell mass quality, and trophectoderm appearance. Results will be reported as the proportion of embryos achieving good-quality blastocyst grade per standard scoring system.
Time frame
From embryo warming until embryo transfer (within 2-6 hours post-warming)4
Technical or embryological adverse events.
defined as any unexpected or unfavorable technical or laboratory-related events occurring during blastocyst warming, handling, culture, or preparation for transfer, including damage to the embryo, procedural errors, or protocol deviations that may affect embryo viability.
Time frame
From blastocyst warming until embryo transfer, within the same clinical procedure (up to 6 hours post-warming)Sponsors and contacts
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Source ClinicalTrials.gov