Developmental potential of fully intact and partially damaged cryopreserved embryos after laser-assisted removal of necrotic blastomeres and post-thaw culture selection

Objective: Partially damaged frozen and thawed embryos are currently considered to have a lower viability than intact ones. This study was undertaken to compare the performance of intact frozen, and thawed embryos with that of partially damaged embryos after removal of the necrotic blastomeres. Design: Observational clinical series. Setting: Private hospital. Patient(s): Three hundred twenty-six infertile couples undergoing frozen embryo transfer. Intervention(s): Removal of necrotic blastomeres from frozen-thawed human embryos. Main Outcome Measure(s): Pregnancy and implantations rates. Result(s): Outcomes of frozen embryo transfer cycles in which all embryos were fully intact (group 1) were compared with those in which all embryos have lost 1-2 blastomeres (group 2) or 3-4 blastomeres (group 3). Laser-assisted hatching was performed in all embryos, and necrotic blastomeres were removed from partially damaged embryos on this occasion. Only embryos that resumed mitotic activity after thawing were transferred. Comparable clinical pregnancy rates (PR) (38.7%, 39.6%, and 29.4%), delivery rate (34.4%, 34.0%, and 29.4%), and implantation rates (21.6%, 21.4%, and 17.2%) were obtained in groups 1, 2, and 3, respectively. Conclusion(S): The developmental potential of partially damaged frozen, and thawed embryos can be equivalent to fully survived embryos if the necrotic blastomeres are removed from the partially damaged embryos and only those of them that show post-thaw cleavage are selected for transfer.