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caso clínico Discussion Live birth after transfer of vitrified-warmed embryo - Z . Z hang et al Cryopreservation of human oocytes has long been postulated to be a potentially useful addition to the range of techniques available in assisted reproduction laboratories. It would permit the storage of reproductive potential for women at risk of loss of fertility when undergoing cytotoxic therapy, allow storage of oocytes when sperm retrieval 404 is not possible in a cycle of IVF treatment. Oocyte cryopreservation offers more advantages compared to embryo freezing, such as fertility preservation in women at risk of losing fertility due to oncological treatment or chronic disease, egg donation, and postponing childbirth, and eliminates religious and/or other ethical, legal, and moral concerns of embryo freezing5. Numerous individual studies investigating the different reproductive outcomes of cryopreservation on human embryos, immature or mature oocytes, or ovarian tissues have been reported. Currently, embryo and mature oocyte cryopreservation following IVF are the only methods endorsed by the American Society of Reproductive Medicine (ASRM)6 and recommended by the American Society of Clinical Oncology (ASCO) for fertility preservation for patients with cancer7. Oocyte cryopreservation has improved dramatically in recent years and is receiving widespread clinical use. Novel approaches to further improve success, as well as improved methods to assess this success will aid in continued improvement1. Oocyte freezing confers thermal and chemical stress upon the oolemma and various other intracellular structures due to the formation of ice crystals. The lipid profiles of oocytes and embryos are closely associated with both, the degrees of their membrane fluidity, as well as the degree of chilling and freezing injuries that may occur during cryopreservation. Jaehun et al show that the identified phospholipids can be used as potential biomarkers of oocyte undergoing vitrification and will allow for the development of strategies to preserve phospholipids during oocyte cryopreservation8. However, we generally achieve better survival and pregnancy rates in vitrification compared to those of slow cooling/rapid thawing cryopreservation9. Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage, spindle configuration, embryonic aneuploidy, and genomic imprinting as compared with fresh and slow-freezing procedures, respectively. Both embryo and oocyte vitrifications are safe applications in female fertility preservation10. The patients with fresh TESA sperm and frozen PESA sperm showed significantly higher high-quality embryo rates than those of fresh ejaculated semen and fresh PESA sperm groups. The implantation rates with fresh TESA sperm and fresh PESA sperm were significantly higher than those of fresh ejaculated semen. The clinical pregnancy and live birth rates with fresh PESA sperm were significantly higher than those of fresh ejaculated semen group11. In our research, the couple with a history of unsuccessful ICSI cycles because of poor embryo quality achieve live birth by using donor sperm.Patients with oligozoospermia may benefit from ICSI treatment. However, some of infertile couples face poor results after ICSI and subsequently use artificial insemination with donor sperm. These couples with a history of unsuccessful ICSI cycles because of poor embryo quality are able to achieve high live birth rate after AID cycles12. Ghoraeian et al.13 demonstrated that men especially with severe oligozoospermia have an elevated risk for chromosome abnormalities in their spermatozoa. These abnormalities might affect fertilisation and pre-embryo formation with less impact on implantation. In conclusion, to the best of our knowledge, this is a rare case of a successful delivery after transfer of vitrified-warmed embryo derived from ICSI with vitrified-warmed oocyte and frozen-thawed sperm after failed fresh ICSI cycle by using sperm of her husband in the same patient. However, further study on the safety of freezing, especially vitrification is needed. References 1. Clark NA, Swain JE. Oocyte cryopreservation: searching for novel improvement strategies. J Assist Reprod Genet 2013; 30 (7): 865-75. 2. Ri-Cheng Chian, Yao Wang, Yi-Ran Li. Oocyte vitrification: advances, progress and future goals. J Assist Reprod Genet 2014; 31 (4): 411-20. 3. Noyes N, Labella PA, James Grifo J, Knopman JM. Oocyte cryopreservation: a feasible fertility preservation option for reproductive age cancer survivors. J Assist Reprod Genet 2010; 27 (8): 495-9. Rev Med Chile 2017; 145: 402-405


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