The efficacy of the transfer of twice frozen-thawed embryos with the vitrification method
Received 27 August 2007; received in revised form 26 November 2007; accepted 26 November 2007. published online 25 February 2008.
Objective
To confirm the clinical benefits of recryopreserved, twice-thawed embryo transfer (ET).
Design
Retrospective study.
Setting
Private fertility clinic.
Patient(s)
Forty-nine women whose embryos had been refrozen after a previous frozen-thawed ET.
Intervention(s)
None.
Main Outcome Measure(s)
Comparison of implantation and pregnancy rates of twice-cryopreserved, twice-thawed embryos versus once-cryopreserved, once-thawed embryos.
Result(s)
The pregnancy rate per ET cycle was 27.8% in the refrozen group and 25.9% in the control group (no statistically significant difference). The implantation rate was 25.0% in the refrozen group and 19.3% in the control group (no statistically significant difference).
Conclusion(s)
The refreezing of supernumerary embryos can prevent ovarian hyperstimulation syndrome in stimulated patients and in those who have experienced repeated failed pregnancies. If unexpected supernumerary embryos are available for recryopreservation after frozen-thawed ET, these embryos may be revitrified for a future transfer.
ABSTRACT