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Updated: Oct 26, 2026
Morphometric Protocol for the Objective Assessment of Blastocyst Behavior During Vitrification and Warming Steps
Published on: February 28, 2019
Effect of the 'Ready-to-Use Vitrification and Warming Kit' on Pregnancy Rates Following Vitrification-warmed
Yamato Mizobe1, Yuji Orita1,2, Kazuhiro Takeuchi1,2
1Takeuchi Ladies Clinic/Center for Reproductive Medicine, Kagoshima-shi, Kagoshima, Japan.
Background:
A newly developed ready-to-use (RtU) vitrification-warming kit enables vitrification in 12-13 min and thawing in 6 min, thereby simplifying culture operations by reducing overall handling time, but its effects on operability and clinical pregnancy rates following frozen-thawed embryo transfer need to be assessed.
Aim:
This study aimed to compare clinical pregnancy rates between RtU kit and conventional CryoTip method used for vitrification in women undergoing single blastocyst frozen embryo transfer.
Settings And Design:
A retrospective cohort study performed in a random sample of patients who underwent frozen embryo transfer between October 2023 and December 2024.
Materials And Methods:
Blastocyst vitrification was performed using the CryoTip and RtU kit. Only single blastocyst transfers during a cycle of hormone replacement therapy were performed.
Statistical Analysis Used:
Kruskal-Wallis and Chi-squared tests were used with continuity correction.
Results:
The RtU kit demonstrated a higher warming rate than the CryoTip system while maintaining comparable cooling characteristics. No significant differences were observed between groups in pregnancy positivity (68.2 vs. 71.6%), clinical pregnancy (56.2 vs. 65.5%) and miscarriage rates (11.5 vs. 13.9%). Higher live birth rates were observed in the RtU group (54.1% vs. 42.4%).
Conclusions:
The RtU vitrification-warming kit shortened the warming procedure and showed higher live birth rates compared with the CryoTip method. However, the favourable association with live birth did not remain statistically significant after adjustment for confounding factors. Further prospective studies are warranted.
