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Birth of two babies using oocytes that were cryopreserved in a choline-based freezing medium
Carlos J Quintans1, Mónica J Donaldson, M Victoria Bertolino
1Halitus Instituto Médico, Affiliated to the University of Buenos Aires, Marcelo T de Alvear 2084 (C1122AAF), Buenos Aires, Argentina. cquintans@halitus.com
Background:
Oocyte cryopreservation may have significant potential for assisted reproductive technology. However, to date, successful results have been limited. We report a preliminary series of IVF outcomes after fertilization of oocytes that were frozen in a low-sodium medium.
Methods:
In this retrospective analysis, 12 patients (21-41 years old), who underwent IVF in a fertility clinic affiliated to the University of Buenos Aires, had oocytes cryopreserved in a modified phosphate buffered saline medium, in which sodium chloride was replaced by choline chloride. A slow-freezing, rapid-thawing protocol was used and oocytes were inseminated by ICSI. Outcome measures included oocyte survival, fertilization, implantation and pregnancy rates.
Results:
Median oocyte survival was 63%. Median fertilization rate was 59%. Overall implantation rate was 25%. Six clinical pregnancies were achieved; two of these pregnancies went to term resulting in the birth of two babies.
Conclusions:
To the best of our knowledge, these are the first pregnancies and normal births using oocytes that were cryopreserved in a choline-based medium. The small sample size prevents us from concluding that freezing in a low-sodium medium is superior to using a conventional one.