A novel trophectoderm biopsy technique for all blastocyst stages.

Purpose: This study was conducted to assess the effectiveness of a new trophectoderm (TE) biopsy method that does not require prior opening of the zona pellucida at the blastocyst stage.

Methods: TE biopsy was conducted using a modified extrusion method for embryos during the cleavage stage. In this method, culture medium was injected into the perivitelline space to help extrude TE cells from the zona pellucida before TE biopsy.

Results: Our extrusion method preserves the embryo culture environment until immediately before biopsy because it does not require opening of the zona pellucida prior to TE biopsy. Furthermore, this method does not require a waiting time for blastocyst hatching after laser irradiation, thereby minimizing damage to the embryos and maintaining the time schedule of culture operations.

Conclusions: TE biopsy using this novel extrusion method may be useful in various applications, including the collection of TE cells for next-generation sequencing analysis.