Comparison of growth rates of fresh and frozen-thawed embryos according to chromosomal status.

PURPOSE: To report a comparison of growth rates between fresh and frozen-thawed embryos on day 3 and 4 according to chromosomal status during PGD. METHODS: Embryos were biopsied on day 3, fluorescent in situ hybridization performed for aneuploidy detection and growth rates monitored. RESULTS: Based on 241 egg pick up-PGD and 133 frozen embryo transfer-PGD cycles. The development rate of embryos despite their chromosomal status was similar on day 3, however, overall, fresh embryos showed a significantly improved development (> or =6 cell stage; 85.7%) compared to frozen embryos (77.0%; p < 0.003). On day 4 fresh embryos showed accelerated development and further developmental improvements were associated with chromosomal normality (56.1% normal vs. 42.2% aneuploid; p < 0.004). CONCLUSIONS: Cryopreservation slows embryo development regardless of the chromosomal status. However, chromosomal status did not influence the chance of embryo implantation which was the same for fresh and thawed embryos.

Dilemmas encountered with preimplantation diagnosis of aneuploidy in human embryos.

BACKGROUND: An increased embryo aneuploidy rate is associated with advancing maternal age. Preimplantation genetic diagnosis (PGD) using fluorescence in situ hybridisation (FISH) coupled with in vitro fertilisation (IVF)/embryo biopsy provides a powerful tool to improve the take home baby rates for this poor prognostic group. AIM: To report the preliminary findings of a PGD study for aneuploidy screening and to discuss the dilemmas encountered. METHODS: Preimplantation genetic diagnosis was offered in egg pick up-PGD and frozen embryo transfer-PGD cycles. Embryo biopsy was carried out on day 3 and FISH was used to detect chromosomal abnormalities. RESULTS: The outcome of 75 patients, 100 treatment cycles; 62 egg pick up-PGD and 38 frozen embryo transfer-PGD are presented. The embryo biopsy rate, blastomere survival, presence of nuclei and successful FISH rates for egg pick-up and frozen embryo transfer cycles were similar giving a chromosomal abnormality rate of 57.5 and 51.2% for the respective treatment group. The positive pregnancy, clinical pregnancy and implantation rates were, for egg pick up-PGD 22.7, 13.6 and 21.1% and for frozen embryo transfer-PGD 13.8, 10.3 and 10.0%, respectively. CONCLUSIONS: Preimplantation genetic diagnosis coupled with IVF treatment seems to give satisfactory pregnancy rates. The high embryo aneuploidy rates, chromosomal mosaicism and other issues have presented significant ethical and management dilemmas for our physicians and patients alike. These issues highlight the importance of skillful pretreatment counselling for patients considering PGD.