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Frequently asked questions for: FertiVit™ Cooling/Warming

FAQ1: Why are there different color caps on the bottles of FertiVit™ Cooling and Warming?
The FertiVit kits can be used with embryos and oocytes,depending on the type of cell/embryo different media are used:

  • Oocytes: Use all the vials
  • Zygotes: Use the grey vials for cooling, use all the vials for warming
  • Other embryo stages: Only use the grey vials
  • FAQ2: What is the survival rate?
    >90% oocyte survival, >90% embryo survival

    FAQ3: Is oil necessary?

  • When the media are used in droplets: oil is necessary (except for Cooling 5!) to avoid evaporation, and pH/osmolality changes. Never use oil for Cooling 5, as to avoid oil loading in the straw. If drops are used for Cooling 5, wait to prepare these until oocytes/embryos are in Cooling 4.

  • When the media are used in open wells: oil is not necessary.
  • FAQ4: What is the difference with VitriFreeze/Thaw ES?

  • Fertivit can also be used to vitrify and warm oocytes
  • FertiVit is HTF-based (VitriFreeze/Thaw ES is PBS-based)
  • FertiVit contains 6 vials for vitrifying and 6 vials for warming
  • FAQ5: Is incubation necessary?
    All media can be used at room temperature.

    FAQ6: Why does the kit contain so many steps?
    There are several reasons:
    1) Strong reduction of inter-operator variability (no need to mix droplets)
    2) To reduce stresses for the oocyte:
    An oocyte has to endure a lot of chemical and mechanical osmotic stresses during a vitrification process. These stresses can lead to cytoplasmic insufficiencies which in turn are the main cause of poor competence of vitrified oocytes in terms of fertilization and early embryonic development. The more drastically cryoprotectant solutions are added, the more the oocyte will suffer from mechanical stresses (intense shrinkage, excessive flowrate of water/cryoprotectants). This can be lethal for oocytes or impair their functionality. The reason why the outcome is very successful when using FertiVit, is because the many steps in the protocol ensure a very smooth and controlled addition of cryoprotectants to the oocyte, herewith increasing the survival rate and potential of the vitrified oocytes. A higher number of equilibration steps also increases the rate of cryosurvival of germinal vesicles. The same with warming: removal of cryoprotectants has to be done with precaution because the membrane is more weak and the component in the cytoplasm necessary for water exchange is not fully recovered yet. Therefore, for optimal results, smooth addition and removal of cryoprotectants is beneficial.

    FAQ7: Can FertiVit be used for open/non-aseptic vitrification systems?
    Yes, however we strongly recommend closed vitrification systems as to guarantee maximum safety for the patients.

    FAQ8: Can FertiVit be used for non-collapsed blastocysts?
    Yes, FertiVit is designed for this. Due to the high sucrose concentrations used, the blastocysts don't have to be artificially collapsed anymore.


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