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Human Blastocyst Biopsy and Vitrification
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Double Zona Drilling for Trophectoderm Biopsy: A Safe Strategy When Inner Cell Mass Herniates
En-Hui Cheng1, Yi-Pin Lin1, Maw-Sheng Lee2,3,4
1Genetic Diagnosis Laboratory, Lee Women's Hospital, Taichung 40652, Taiwan.
Diagnostics (Basel, Switzerland)
|March 28, 2026
Summary
A double zona pellucida (ZP) opening strategy for trophectoderm (TE) biopsy is safe and effective in preimplantation genetic testing for aneuploidy (PGT-A) cycles, even when the inner cell mass (ICM) herniates. This approach does not compromise reproductive or obstetric outcomes.
Area of Science:
- Reproductive Medicine
- Embryology
- Genetics
Background:
- Laser-assisted zona pellucida (ZP) drilling is standard for trophectoderm (TE) biopsy in IVF.
- Inner cell mass (ICM) herniation through the initial ZP opening can complicate TE biopsy.
Purpose of the Study:
- To assess the clinical and obstetric safety of a double ZP drilling strategy for TE biopsy in PGT-A cycles.
- To compare outcomes between single and double ZP opening approaches for TE biopsy.
Main Methods:
- Retrospective analysis of 560 single euploid embryo transfer cycles.
- Categorization of blastocysts based on ICM/TE herniation patterns and biopsy approach.
- Comparison of clinical outcomes between single and double ZP opening strategies.
Main Results:
- No significant differences in implantation, miscarriage, or live birth rates between single and double ZP opening groups.
- Comparable obstetric and neonatal outcomes (gestational age, birth weight, twinning) between groups.
- Fifteen healthy infants delivered following double ZP opening strategy.
Conclusions:
- Incorporating ICM position into TE biopsy decisions is supported.
- Creating a second ZP opening is clinically feasible and safe.
- The double ZP opening strategy does not compromise reproductive or obstetric outcomes in PGT-A cycles.

