Cocultured blastocyst cryopreservation: experience of more than 500 transfer cycles.
OBJECTIVE
To present our experience using cocultured cryopreserved and transferred blastocysts.


METHODS
Retrospective study of patients undergoing transfer of cryopreserved blastocysts.


METHODS
Three different IVF centers.


METHODS
Four hundred sixty-seven thawed cycles from January 1991 to June 1994.


METHODS
Pregnancy rate per cycle after transfer of pre-embryos developed from thawed blastocysts.


RESULTS
One thousand two hundred thirty-nine blastocysts were thawed. Of these, 1,033 (83%) survived thawing and were transferred. Five hundred sixty-three thawed cycles resulted in 516 (92%) receiving intrauterine transfer. One hundred twelve clinical pregnancies were established, resulting in a 21.7% pregnancy per transfer with a 19% ongoing rate. The implantation rate of 13.4% results from 138 implanted pre-embryos. There was a higher PR in the programmed cycle (79/302; 26.2%) compared with the natural cycle (6/47;13%).


CONCLUSIONS
Freezing at the blastocyst stage is a proven and reliable method in IVF technology. Although there may be fewer pre-embryos, their ability to implant appears to approach the potential of a fresh transfer.
Kaufman
R A
RA
Augusta Reproductive Biology Associates, Georgia 30904, USA.
Menezo
Y
Y
Hazout
A
A
Nicollet
B
B
DuMont
M
M
Servy
E J
EJ
D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D012189:Retrospective Studies