Human embryo cryopreservation, extrinsic and intrinsic parameters of success.
Freezing and thawing (F - T) was applied to 490 early human embryos using propanediol as cryoprotectant. The survival rate of embryos frozen with propanediol alone did not exceed 31% (26/83). The combination of propanediol and sucrose, however, significantly increased the percentage of surviving (248/407 = 61%) and intact (188/407 = 46%) embryos and seemed to enhance embryo viability as suggested by the implantation rate (14.5 versus 8%) without, however, any statistical significance. Embryo survival, but not viability, was correlated with morphological features, whereas neither the age of embryos (1, 2 or 3 days post-insemination) nor the segmentation stage (regular or intermediate) were involved in F - T ability. Thirty-eight F - T embryos implanted when replaced in utero, representing 8% of all F - T embryos and 14% of the F - T replaced embryos. The pregnancy rate per transfer reached 19% (35/185) and was identical to the pregnancy rate per transfer of fresh embryos (253/1149 = 22%). In oocyte donation, too, embryo freezing did not impair the pregnancy rate (25%). In spontaneous cycles, synchronous transfer gave better results than asynchronous transfers (20 versus 10%), but spontaneous cycles had no significant advantage (16% pregnancy/transfer) as compared to stimulated (26%) and artificial (27%) cycles.
INSERM U.173, Hôpital Necker, Paris, France.
J
J
Mandelbaum
A M
AM
Junca
M
M
Plachot
M O
MO
Alnot
S
S
Alvarez
C
C
Debache
J
J
Salat-Baroux
J
J
Cohen
D001757:Blastomeres / Q000166:cytology; D003451:Cryoprotective Agents; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology; D005615:Freezing; D006801:Humans; D011379:Prognosis; D019946:Propylene Glycol; D011409:Propylene Glycols; D013395:Sucrose; D014019:Tissue Donors; D014021:Tissue Preservation / Q000379:methods*
D003451:Cryoprotective Agents; D011409:Propylene Glycols; D013395:Sucrose; D019946:Propylene Glycol