Parameters predicting the implantation rate of thawed IVF/ICSI embryos: a retrospective study.
Single embryo transfer is becoming increasingly popular in IVF/ICSI. More IVF/ICSI cycles therefore include freezing of high quality embryos, and the cumulative effect of such cycles becomes more important. To improve the results obtained using frozen-thawed embryos, the predictive value of embryo and patient characteristics was analysed retrospectively. Excess embryos were frozen on day 2 according to routine procedures and thawed 24 h before transfer. The women were either treated with oestradiol/progesterone, or the transfer took place after a natural cycle. Of 1777 embryos thawed, 1360 survived (survival rate 76.5%). In the 410 transfer cycles, 819 embryos were transferred, giving 109 positive serum HCG tests and 69 clinical pregnancies. The implantation rate was 10.4%. Five parameters were positively related to implantation: (i) four or more cells at the freezing time (day 2); (ii) resumption of mitosis after thawing; (iii) more than six cells at transfer (day 3); (iv) assisted hatching and (v) child in a previous fresh cycle. The relative predictive value of these parameters may be a guideline for the selection of embryos used for transfer. Assisted hatching may become routine in freeze-thaw cycles if its utility is confirmed in subsequent studies.
Gabrielsen
A
A
Ciconia, Saralyst allé 50, DK-8270 Højbjerg, Denmark. ag@ciconia.dk
Fedder
J
J
Agerholm
I
I
D000328:Adult; D006063:Chorionic Gonadotropin; D015925:Cryopreservation / Q000379:methods*; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D004958:Estradiol; D005260:Female; D006801:Humans; D008938:Mitosis / Q000502:physiology; D011247:Pregnancy; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic; D016019:Survival Analysis; D016896:Treatment Outcome
D006063:Chorionic Gonadotropin; D004958:Estradiol