Freezing within 2 h from oocyte retrieval increases the efficiency of human oocyte cryopreservation when using a slow freezing/rapid thawing protocol with high sucrose concentration.
BACKGROUND
A number of factors influence the success of oocyte cryopreservation and subsequent ICSI. The aim of the present study is to establish the ideal time, after oocyte retrieval, for human oocyte cryopreservation via slow freezing/rapid thawing protocol with 0.3 M sucrose concentration in cryoprotectant solution (SF/RT 0.3 M).


METHODS
Retrospective study with 75 patients on the clinical outcome of 93 oocyte thawing cycles divided into three groups. Group A: freezing within 2 h from oocyte retrieval. Group B: freezing between 2 and 3 h from retrieval. Group C: freezing after 3 h.


RESULTS
The rate of best quality embryos was significantly higher (35.2%; P = 0.050) in Group A than in Group C (14.1%). Pregnancy and implantation rates were 39.1% (9/23) and 18.5% (10/54) in Group A. Nine clinical pregnancies per 124 thawed (7.3%) and 73 injected (12.3%) oocytes were observed in Group A versus 3 pregnancies per 174 thawed, 103 injected (1.7%, 2.9%, P = 0.046 and 0.0049) in Group B and 4 per 139 thawed, 88 injected (2.9%, 4.5%, NS) in Group C. The overall yield from oocytes cryopreserved within 2 h of retrieval was 8.1 implantations per 100 oocytes thawed.


CONCLUSIONS
Embryo quality and clinical outcome of thawing cycles were significantly improved when oocyte cryopreservation by SF/RT 0.3 M was carried out within 2 h from oocyte retrieval.
Parmegiani
L
L
Reproductive Medicine Unit, GynePro Medical Centers, Via Tranquillo Cremona 8, 40137 Bologna, Italy. l.parmegiani@gynepro.it
Cognigni
G E
GE
Bernardi
S
S
Ciampaglia
W
W
Infante
F
F
Pocognoli
P
P
de Fatis
C Tabarelli
CT
Troilo
E
E
Filicori
M
M
D000328:Adult; D002470:Cell Survival; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000008:administration & dosage; D004624:Embryo Transfer; D005260:Female; D005615:Freezing; D006801:Humans; D054315:Oocyte Retrieval / Q000379:methods*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic; D013395:Sucrose / Q000008:administration & dosage; D013997:Time Factors
D003451:Cryoprotective Agents; D013395:Sucrose