© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permission@oup.com. Human Reproduction, Vol.35, No.4, pp. 785–795, 2020 Advance Access Publication on April 2, 2020 doi:10.1093/humrep/deaa009 ORIGINAL ARTICLE Embryology Definition of a clinical strategy to enhance the efcacy, efciency and safety of egg donation cycles with imported vitrified oocytes Laura Rienzi 1,2, *, Danilo Cimadomo 1,2 , Roberta Maggiulli 1 , Alberto Vaiarelli 1 , Ludovica Dusi 2 , Laura Bufo 2 , Maria Giulia Amendola 1 , Silvia Colamaria 1 , Maddalena Giuliani 1 , Giulietta Bruno 1 , Marta Stoppa 1 , and Filippo Maria Ubaldi 1,2 1 Clinica Valle Giulia, GENERA Center for Reproductive Medicine, Rome, Italy 2 GENERA Veneto, GENERA Center for Reproductive Medicine, Marostica, Italy *Correspondence address. GENERA Centers for Reproductive Medicine, via G. de Notaris 2b, 00197, Rome, Italy. E-mail: rienzi@generaroma.it Submitted on October 5, 2019; resubmitted on January 13, 2020; editorial decision on January 17, 2020 STUDY QUESTION: Which is the most suitable clinical strategy in egg donation IVF cycles conducted with imported donated vitrified oocytes? SUMMARY ANSWER: The importation, and allocation, of at least eight vitrified eggs per couple during an egg donation cycle is associated with a high cumulative live birth delivery rate per cycle, as well as the confident adoption of a single blastocyst transfer strategy to minimize the risk of multiple pregnancies. WHAT IS KNOWN ALREADY: IVF using donor eggs is commonly used worldwide to treat women who are unable to conceive with their own oocytes. In 2014, the Constitutional Court (n.162/2014) gave permission for gamete donation to be allowed for ART in Italy. Initially recommended as a therapeutic approach for premature ovarian insufciency, the use of donated oocytes has become more and more common. In countries such as Italy, fresh oocyte donation is theoretically possible, but practically impossible due to the lack of donors. In fact, the Italian law does not allow reimbursement to the young women, who can only voluntarily donate their eggs. Therefore, Italian IVF centers have established several collaborations with international oocyte cryo-banks. The most popular workflow involves the importation of donated oocytes that have been vitrified. However, recent evidence has questioned the overall efcacy of such an approach. This is because detrimental efects arising from oocyte vitrification and warming might reduce the number of eggs available for insemination, with a consequential reduction in the achievable live birth rate per cycle. STUDY DESIGN, SIZE, DURATION: This was a longitudinal cohort study, conducted between October 2015 and December 2018 at two private IVF centers. Overall, 273 couples were treated (mean maternal age: 42.5 ± 3.5 years, range: 31–50 years; mean donor age: 25.7 ± 4.2, 20–35 years) with oocytes purchased from three diferent Spanish egg banks. PARTICIPANTS/MATERIALS, SETTING, METHODS: We performed an overall analysis, as well as several sub-analyses clustering the data according to the year of treatment (2015–2016, 2017 or 2018), the number of warmed (6, 7, 8 or 9) and surviving oocytes (≤4, 5, 6, 7, 8 or 9) and the cycle strategy adopted (cleavage stage embryo transfer and vitrification, cleavage stage embryo transfer and blastocyst vitrification, blastocyst stage embryo transfer and vitrification). This study aimed to create a workflow to maximize IVF efcacy, efciency, and safety, during egg donation cycles with imported vitrified oocytes. The primary outcome was the cumulative live birth delivery rate among completed cycles (i.e. cycles where at least a delivery of a live birth was achieved, or no embryo was produced/left to transfer). All cycles, along with their embryological, obstetric and neonatal outcomes, were registered and inspected. MAIN RESULTS AND THE ROLE OF CHANCE: The survival rate after warming was 86 ± 16%. When 6, 7, 8 and 9 oocytes were warmed, 94, 100, 72 and 70% of cycles were completed, resulting in 35, 44, 69 and 59% cumulative live birth delivery rates per completed cycle, respectively. When ≤4, 5, 6, 7, 8 and 9 oocytes survived, 98, 94, 85, 84, 66 and 68% of cycles were completed, resulting in 16, 46, 50, . . . . . . . . . Downloaded from https://academic.oup.com/humrep/article/35/4/785/5815140 by guest on 28 February 2023