Egg Freezing & Embryo Freezing

Vitrification or Cryopreservation

Cryopreservation is the freezing of biological matter to preserve it for future use, and is utilized as a method of fertility preservation. It involves cooling and storing of Sperms, Eggs and Embryos at very low temperatures to maintain their viability.

A woman’s eggs, a man’s sperm, or a fertilized embryo are all capable of being cryopreserved. When the woman or couple is ready, the eggs or the embryo, as the case may be, are thawed (Warmed)fertilized, and transferred to the uterus.

This procedure allows an individual or a couple to protect their biological reproductive material at a time it is healthiest, before age or health conditions decrease their quality or quantity. Once the materials are preserved, they may be used in future in assisted reproductive technologies (ART) to achieve a pregnancy.

Scientifically theses eggs and embryos can be frozen for multiple years without any detrimental effect on them. However, the ICMR guidelines suggest that they can be frozen for up to 5 years.

A couple may opt for Vitrification for any one of the following reasons:

  • For health reasons; for example, the need for cancer treatment that may damage reproductive abilities, degenerative reproductive system disorders,
  • Prioritization of career, educational, or personal goals.
  • The wish to delay child bearing for any other personal reason.
  • Embryo transfer is cancelled due to a number of reasons.
  • Preserving “leftover” embryos from an IVF treatment to use at a later date in case the present cycle doesn’t work or for another baby.

If a patient has embryos vitrified at the clinic. They do not need to undergo egg retrieval. They can thaw the embryo and get a transfer done. Only medications to support the pregnancy need to be taken

Why is oocyte vitrification done?

Oocyte vitrification is done in the following cases:

  • Social: Absence of the male partner so the female may want to preserve her fertility
  • Fertility preservation before taking toxic drugs for treatment like cancer. Only mature oocytes are vitrified after denudation

The process:

Vitrification is done by washing the oocytes or embryos in media within a stipulated time, once the washing is completed the embryo or eggs are loaded on a loading device and submerged immediately into liquid nitrogen. They are stored in liquid nitrogen at all times (-196c)
How many embryos or oocytes can be frozen on one straw?

The number of embryos depends on the stage of their development.

  • Cleavage stage – embryos then no more than three embryos should be vitrified per straw
  • Blastocyst stage – their diameter is bigger so no more than two should be vitrified on one straw
  • For oocytes – No more than four oocytes should be frozen on one straw

Essentials for a good vitrification program

  • Embryologist trained in vitrification
  • Vitrifying only good embryos
  • Adhering to the defines number of embryos or oocytes on each straw

However, you need to be aware that sometimes even though all the precaution is taken the embryos may not survive. Embryo survival rate after vitrification is 96%

There is currently no evidence that cryopreservation negatively impacts the outcome of the child.

Frequently asked questions

Embryo cryopreservation, also known as embryo freezing, is typically performed at the blastocyst stage, which occurs about five to six days after fertilisation. At this stage, the embryo has developed into a hollow ball of cells and is more likely to survive the freezing and thawing process. Additionally, blastocyst-stage embryos have been shown to have higher implantation rates and lower risks of chromosomal abnormalities. However, the decision to freeze embryos at a particular stage may depend on individual circumstances and should be discussed with a healthcare provider.

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