AH is done at the time of embryo transfer for:
AH is done at the time of embryo cryopreservation. This is a technique that has been widely used for over a decade. The embryo is collapsed with the laser by making a small hole in the zona pellucida. The reason we collapse embryos before freezing them is to make sure that the fluid in the cavity of the embryo is removed, which lets the embryo fully compact inside the zona.
Embryos that are biopsied for pre-implantation genetic testing (PGT) can be hatched on Day 3 of embryo growth. This is done so that the embryo hatches out of the zona on Day 5 when we are ready to perform the biopsy. The laser is used again during the biopsy to detach a few cells from the embryo.