Oocyte slow freezing using a 0.2–0.3 M sucrose concentration protocol: is it really the time to trash the cryopreservation machine?

We present oocyte slow-freezing outcomes using a differential sucrose concentration during dehydration (0.2 M) and rehydration (0.3 M).

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Veronica Bianchi, Ph.D., Michela Lappi, B.Sc., Maria Antonietta Bonu, B.Sc., Andrea Borini, M.D.

Vol 97, Issue 5, Pages 1101-1107, May 2012



To update results on outcomes with frozen/thawed oocytes using a differential sucrose concentration during dehydration (0.2 M) and rehydration (0.3 M), combined with a one-step propanediol exposure.


Retrospective cohort study.


Private IVF centers.


Infertile couples undergoing IVF treatment.


Oocyte thawing cycles between May 2004 and December 2010.

Main Outcome Measure(s):

Survival, fertilization, and cleavage rates were reported to evaluate biological outcomes. Clinical pregnancy and implantation rates were analyzed as markers of efficiency.


Three hundred forty-two patients and 443 cycles were monitored; the survival was 71.8%, fertilization 77.9%, and of the embryos obtained 83.8% were classified as grade 1 and 2. Three hundred ninety-four transfers were performed, resulting in 90 pregnancies. The pregnancy rate per transfer was 22.8% and per patient was 26.3%, with 122 gestational sacs. The implantation rate per embryo was 13.5%. Patients were divided into three groups according to their age: ≤34 years (group A), 35–38 years (group B), and ≥39 years (group C). Biological outcomes were comparable in all three groups, whereas the pregnancy rate per transfer was higher in the first group (27.7% vs. 21.4% and 17.6%). The implantation rates per injected egg were 11.8%, 8.0%, and 7.5% for the three groups, respectively.


The biological and clinical data obtained on 443 cycles are consistent with our previous results showing that slow freezing of oocytes can be a valid tool in IVF practice when performed with a suitable protocol.

Read the full text at: http://www.fertstert.org/article/S0015-0282(12)00186-0/fulltext

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.