Clinical experience and applications of oocyte cryopreservation

Purpose To evaluate the role of co-transfer of embryos derived from vitrified oocytes accumulated during the previous modified natural cycles and an embryo developed from the last one as an alternative to repetitive single embryo transfer in a fresh modified natural cycle. Methods Thirty-six patients underwent ICSI procedure with three frozen natural oocytes supplemented by a fresh one obtained from the fourth modified natural cycle. Thirty-one controls received at least three consecutive single embryo transfer in a fresh modified natural cycle. Results In the study group the oocyte retrieval, survival and total fertilization rate were 73.0 %, 78.1 %, and 64.5 %, respectively. Fifty-two embryos were transferred in 29 transfers. In the control group the oocyte retrieval and fertilization rate was 77.4 % and 83.7 %, respectively. Fifty single embryo transfers were performed. Of a total 14 pregnancies obtained in the study group 10 were defined as clinical and 4 as abortions. In the control group a total of 8 single clinical pregnancies and 2 miscarriages were encountered. The overall (20.0 % vs 48.2 %) and the clinical (16.0 % vs 34.4 %) pregnancy rate were significantly higher in the study group having cumulative embryo transfer following the oocyte accumulation. Conclusions These data demonstrate that the co-transfer of embryos derived from vitrified oocytes accumulated during the previous modified natural cycles and an embryo developed from the last fresh modified natural cycle assure an excellent clinical outcome with the overall and clinical pregnancy rate significantly higher compared to the repetitive single embryo transfer in a fresh modified natural cycle.

Section: Discussionmentioning

confidence: 99%

Accumulation of oocytes from a few modified natural cycles to improve IVF results: a pilot study

Greco

Litwicka

Arrivi

et al. 2013

“…The number of babies born following in vitro fertilization of cryopreserved oocytes has steadily increased over the last few years [5][6][7][8][9][10]. Much of this growth can be attributed to changes in the law in Italy, which resulted in the prohibition of embryo cryopreservation.…”

Section: Discussionmentioning

confidence: 99%

“…The resurgence of interest in human oocyte cryopreservation as a consequence of a number of reports suggesting that it may be a safe option in appropriate circumstances [1][2][3][4] has led to its clinical application and reports of a number of live births [5][6][7][8][9][10]. Although this approach has been adopted as an adjunct to routine IVF practice in Italy, this is predominantly a consequence of legal developments which resulted in the prohibition of the alternative, and more widepread, option of embryo cryopreservation.…”

Section: Introductionmentioning

confidence: 99%

Live birth following transfer of a cryopreserved embryo generated from a cryopreserved oocyte and a cryopreserved sperm: Case report

Gook

Hale

Edgar

2006

As is the case with non-frozen oocytes, the efficient and successful use of cryopreserved oocytes in human assisted reproduction is, in part, dependent on the ability to apply selection criteria when choosing the 'best' embryos for transfer from a cohort. In many cases this, in turn, will necessitate the cryopreservation of non-transferred embryos to minimise the risk of multiple pregnancy. It is therefore important to establish that an embryo, generated by fertilization of a frozen-thawed oocyte, can be capable of surviving subsequent cryopreservation while retaining the potential for normal development. In this case report, we document the delivery of a normal male infant following transfer of a frozen-thawed embryo, generated by the fertilization of a frozen-thawed oocyte by a frozen-thawed sperm.

“…Cryopreservation may lead to the premature release of cortical granules, hardening of the zona, and depolymerization of meiotic spindles (1). In recent years, modifications of the slow-freezing method or vitrification have significantly improved the survival rate (2)(3)(4)(5)(6). Intracytoplasmic sperm injection (ICSI) is widely used as an effective technique to achieve fertilization for cryopreserved oocytes.…”

Section: Introductionmentioning

confidence: 99%

Short Communication: Cryopreserved Sibling Oocytes and Intracytoplasmic Sperm Injection Rescue Unexpectedly Poor Fertilization in Conventional In Vitro Fertilization

Chen

Lien

Chang

et al. 2004

Purpose : To report a successful pregnancy from cryopreserved sibling oocytes and intracytoplasmic sperm injection (ICSI) for an infertile couple with an unexpectedly low fertilization rate in the fresh in vitro fertilization (IVF) cycle. Methods : The woman had bilateral tubal obstruction and polycystic ovarian syndrome. The man had normal semen parameters. The couple underwent a cycle of controlled ovarian hyperstimulation in that 20 oocytes were retrieved. Twelve oocytes were conventionally inseminated and eight were cryopreserved using a slow freezing method. However, only one oocyte was fertilized, and no pregnancy was achieved. In the next cycle, the frozen oocytes were thawed and ICSI was performed. Results : After thawing, seven oocytes (88%) survived and one was damaged. Six were at the metaphase II stage and were injected. Five (83%) achieved normal fertilization, and all of them cleaved (100%). After replacement of the embryos, a singleton pregnancy developed. A healthy female baby was delivered at term. Karyotyping revealed 46, XX. Conclusions : In addition to well-known indications, cryopreservation of excess sibling oocytes for patients receiving IVF has a possible advantage of preventing unexpectedly low fertilization rate or fertilization failures.