Comparison of concomitant outcome achieved with fresh and cryopreserved donor oocytes vitrified by the Cryotop method.
OBJECTIVE
To evaluate the outcome of oocyte vitrification using the Cryotop method, observed in an egg donation program by simultaneously evaluating embryos derived from vitrified and fresh oocytes coming from the same stimulated cycle.


METHODS
Cohort prospective randomized study.


METHODS
Instituto Valenciano de Infertilidad (IVI) Valencia, Spain.


METHODS
Thirty oocyte donors and 30 recipients with informed consents.


METHODS
Vitrification by the Cryotop method. Warming 1 hour after vitrification. Microinjection of surviving MII and fresh oocytes, evaluation of fertilization, embryo development, and clinical results.


METHODS
Survival, fertilization, and cleavage rate. Embryo quality, pregnancy rate (PR), and implantation rate.


RESULTS
Survival rate observed was 96.7%. There was no difference in fertilization rates (76.3% and 82.2%), day 2 cleavage (94.2% and 97.8%), day 3 cleavage (80.8% and 80.5%), and blastocyst formation (48.7% and 47.5%) for vitrified and fresh oocytes, respectively. Embryo quality on day 3 and on day 5-6 were similar for vitrification and fresh oocyte group (80.8% vs. 80.5% and 81.1% vs. 70%, respectively). A total of 23 embryo transfers were carried out in the vitrification group. Pregnancy rates, implantation rates, miscarriage rates, and ongoing PR were 65.2%, 40.8%, 20%, and 47.8%, respectively.


CONCLUSIONS
The Cryotop method preserves the potential of vitrified oocytes to fertilize and further develop, which is similar, when evaluated simultaneously, to fresh counterparts. Excellent clinical outcome indicates the possible use of this technology for egg donation programs, as well as a high potential for establishing oocyte banking.
Cobo
Ana
A
IVI Universidad de Valencia, Valencia, Spain. acobo@ivi.es
Kuwayama
Masashigue
M
Pérez
Sonia
S
Ruiz
Amparo
A
Pellicer
Antonio
A
Remohí
José
J
D000293:Adolescent; D000328:Adult; D018929:Cell Culture Techniques; D015925:Cryopreservation; D003470:Culture Media; D004624:Embryo Transfer / Q000706:statistics & numerical data; D004958:Estradiol / Q000031:analogs & derivatives / Q000627:therapeutic use; D004966:Estrogens, Conjugated (USP) / Q000627:therapeutic use; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro; D006801:Humans; D018587:Oocyte Donation; D009865:Oocytes / Q000166:cytology* / Q000473:pathology; D011247:Pregnancy; D011256:Pregnancy Outcome
D003470:Culture Media; D004966:Estrogens, Conjugated (USP); D004958:Estradiol