Egg Cryopreservation allows a woman to save her eggs in a frozen state till the desired time when she prefers conception.

Sometimes when a woman is using IVF to conceive a child, she can choose to preserve the remaining harvested eggs for future use, like for when she wants to have another child. Or she can also choose to donate the frozen eggs to other women who are struggling to conceive.

Preservation Procedure

Egg cryopreservation follows the below steps:

1. Ovarian Stimulation - Medications will be given to stimulate the ovaries to produce multiple eggs.
2. Egg Retrieval - It is done in the hospital / clinic under sedation. Generally, a transvaginal ultrasound is used in which a probe is inserted into the vagina to locate the follicles. Then a needle is inserted to remove the eggs from the follicles. Usually, around 15 eggs per cycle are retrieved. One might feel slight discomfort and cramping after the procedure.
3. Freezing - Retrieved eggs are then harvested and cooled to a subzero temperature to freeze them for future use. Cryoprotectants are used in this cooling process to prevent ice crystals from forming.

When one feels ready for pregnancy, these preserved frozen eggs are thawed and then combined with fresh or frozen sperms in the clinical lab. If everything goes well and the egg gets fertilised, the resulting embryo is then transferred to the uterus for implantation during the IVF cycle.

Embryo Cryopreservation is the process of freezing and storing leftover embryos of an IVF cycle for future use. If the IVF process fails, embryo cryopreservation provides a woman another chance to conceive through Frozen Embryo Transfer (FET), without repeating another ovarian stimulation and retrieval cycle. So there is no need to repeat the whole IVF cycle.

Embryo cryopreservation also helps to preserve the fertility of women who are not yet ready for second childbearing.

Frozen embryos can also be donated to infertile couples.

Unused frozen embryos can be donated for research also (upon approval from the couple).

Preservation Procedure

Embryo cryopreservation follows the below steps:

1. Ovarian Stimulation - Medications will be given to stimulate the ovaries to produce multiple eggs.
2. Egg Retrieval - It is done in the hospital / clinic under sedation. Generally, a transvaginal ultrasound is used in which a probe is inserted into the vagina to locate the follicles. Then a needle is inserted to remove the eggs from the follicles. Usually, around 15 eggs per cycle are retrieved. One might feel slight discomfort and cramping after the procedure.
3. Fertilisation - Retrieved eggs are allowed to fertilize with the partner’s sperms in the lab to form embryos. Embryos are developed in the lab for 2 - 5 days before transferring to the uterus cavity.
4. Freezing - Only 1 - 2 embryos are transferred. Potential ones from the rest of the embryos are preserved in frozen state using two distinct processes. Embryos are frozen slowly over a period of 2 - 4 hours.
   
   The main concern when freezing embryos is the formation of ice in the cells and between them, which can damage them. Therefore, it is imperative to protect the embryos during the freezing process by using special ‘cryoprotective agents’.
   
   The frozen embryos are then stored in sealed liquid nitrogen containers where they can remain for years without damage or degeneration.

When required, the cryopreserved frozen embryos are thawed and then transferred to the uterus for implantation during the IVF cycle. Not all frozen embryos are viable after thawing, but the recovery rate is excellent.