부산대학교 도서관

BACKGROUND: Assisted hatching (AH) in fresh embryo transfer (ET) cycles increases the implantation and pregnancy rates, especially in women with a poor prognosis, repeated implantation failures and in older women. Little information exists in the literature regarding the role of AH in frozenthawed embryo transfer (FET) cycles. METHODS: Embryos were cryopreserved at the cleavage stage. On the day of FET, 160 patients were randomized according to a computer-generated randomization list in sealed envelopes into the AH group and the control group. The patients and the clinicians were blinded to the group assigned. In the AH group, the outer half of the zona pellucida over a quarter of the diameter of zona was removed using a 1480?nm non-contact laser. RESULTS: The two groups were comparable in terms of demographic characteristics, ovarian response of the stimulated cycle and quality of fresh and frozenthawed embryos. No differences in implantation, pregnancy and multiple pregnancy rates were found between the two groups. There was a non-significant trend of a higher implantation rate in the AH group when the zona thickness was =16?mm. CONCLUSION: Laser AH did not improve the implantation rate of FET cycles and should not be performed routinely in all frozenthawed embryos at the cleavage stage. [ABSTRACT FROM AUTHOR]