During Fertility 2021, an interesting poster was presented by researchers from Cardiff University and London Women’s Clinic.
The number of oocytes or embryos to be loaded onto the Cryotop® and the spatial arrangement on the strip is often a matter or concern and debate among embryologists as these two issues may influence the cooling rate during vitrification.
Researchers from Cardiff University/LWC have investigated these topics in a study presented at Fertility 2021. The authors have created a computer model that builds the Cryotop® as it would be seen during vitrification with specimens loaded on its strip. They have set in the computer simulation, multiple embryos mounted in various locations and modelled the temperature in the system changing over time after being submerged in liquid nitrogen.
Their results have shown that the number of oocytes or embryos and the different spacial arrangements have minimal effect on cooling rates, as long as the droplet size and safe timeframes during vitrification remain within manufacturer’s guidelines. The number of oocytes or embryos mounted in one cryo-device is usually determined by the embryologists in accordance with the patient and IVF treatment characteristics. The Cryotop® consists of a polypropylene strip attached to a plastic handle that allows loading of one to four oocytes or embryos with a minimum volume (about 0.1 μl), providing rapid cooling and warming rates that will finally lead to an excellent survival rate.