Oocyte vitrification/storage/handling/transportation/warming, effect on survival and clinical results in donation programmes

Nowadays human gamete and embryo cryopreservation is integral to Assisted Reproductive (AR) techniques in optimizing treatment management and results. Cryopreserved cells can be stored for years and transported between authorized AR centres. Particularly in the case of heterologous insemination techniques, the use of frozen gametes facilitates donor/recipient matching and allows time for donor testing. Cryopreserved oocytes, spermatozoa and embryos can be shipped between specialized donation and cryopreservation centres (gamete cryobanks) and AR centres carrying out treatment on recipient patients. However, appropriate procedures need to be in place to minimize physical shocks and contamination during cryostorage, handling and shipping. The aim of the meeting “Shipping Gametes and Embryos” held in Milan on February 4th, 2017 was to address these critical aspects, including regulation and legal requirements, and to propose some troubleshooting procedures in the case of emergencies. A specific example of the possible negative impact of handling and transportation on survival of oocytes shipped between Spain and Italy was reported during the meeting: an inappropriate method of shipping reduced by 20% the vitrified oocytes’ survival at warming. The influence of different transportation methods and, in addition, the impact of the number of surviving oocytes used are described in detail through the analysis of original data presented for the first time at this meeting and reported in this article. The general suggestion emerging from this study is to take into account the possible negative impact of handling and different transportation methods on survival at warming and to assign an adequate number of oocytes per treatment, in order to inject a minimum of five oocytes.