Published in:
01-03-2012 | Fertility Preservation
Live birth from oocytes cryopreserved with slow-freezing protocol and thawed after 6 years of storage
Authors:
Giovanni Battista La Sala, Francesco Capodanno, Barbara Valli, Ilaria Rondini, Maria Teresa Villani, Alessia Nicoli
Published in:
Journal of Assisted Reproduction and Genetics
|
Issue 3/2012
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Excerpt
After the birth of more than 900 babies from human cryopreserved oocytes with no apparent increase in congenital anomalies compared to conventional IVF babies [
1], oocyte cryopreservation has become a quite widespread technique in Assisted Reproductive Technologies (ART), even in the female fertility preservation programs. Today two procedures are available for oocyte cryopreservation: slow-freezing (SF), the first protocol introduced, and vitrification (VT) [
2]. The main goal of VT is to achieve high cryoprotectant concentration in order to increase the viscosity of the cryoprotectant solution and to suppress ice nucleation [
3]. Biological and clinical outcomes of SF protocols seem to be less than those obtained with fresh and vitrified oocytes [
4‐
6]. Oocyte cryopreservation is usually used in ART laboratories for supernumerary oocyte storage after Controlled Ovarian Stimulation (COS) [
4], prevention of Ovarian HyperStimulation Syndrome (OHSS) risk, oocyte accumulation in poor responder patients [
7], and fertility preservation programmes for cancer patients [
8‐
10] or for social reasons [
11]. Nevertheless, in 2008 the Practice Committee of American Society of Reproductive Medicine (ASRM) concluded that “
Oocyte cryopreservation presently should be considered an experimental technique,” as the data available on the efficacy of oocyte cryopreservation in relation to the length of storage are still limited [
1,
12]. Instead, the ASRM considers embryo cryopreservation a non-experimental technique [
12], with a proven clinical outcome regardless of the length of storage [
13,
14]. Unfortunately, there are limited data concerning children born from long-term cryopreserved oocytes [
1]. The first live birth obtained from oocytes stored for a long period was reported by Yang et al. in 2007: oocytes were cryopreserved by SF for fertility preservation before cancer treatment and thawed 6 years later . In 2008, Parmegiani et al. reported a live birth from oocytes cryopreserved by SF after 5 years of storage in a patient who underwent infertility treatment. Kim and Hong [
17] recently described a similar result, reporting a live baby born from vitrified oocytes thawed 5 years later . …