Cryopreservation is a process which involves preserving of biologically intact living cells at extreme low temperatures usually at -196oC/-321oF in liquid Nitrogen. At these low temperature, the biological activity of the cells stop, but the longevity of the cell is maintained indefinitely until future use.

Cryopreservation is an integral part of ART, where usually freezing of the following are done:

1) Sperm cryopreservation

2) Oocyte cryopreservation

3) Embryo cryopreservation

4) Ovarian tissue cryopreservation

1) Sperm cryopreservation:

Sperm freezing is routinely done in the following cases:

• As back-up- Traveling overseas or in case of difficulty in producing the sample on the day of treatment

• Low sperm count or deteriorating sperm quality

• Medical condition or medical treatment (like vasectomy, cancer) that may result in infertility later in life

• High risk jobs- Military, hazardous chemicals, exposure to radiation, extreme temperatures.

• Sperm donation (when sperms are to be donated)

This procedure involves freezing of sperm cells. The frozen sperm cells are later thawed and used for fertility treatment to induce pregnancy.

Cryopreservation process involves:

• Both the couples are screened for infectious diseases (HIV, Hep B, Hep C, VDRL).

• Written consent for freezing and storing of semen sample is taken.

• Semen sample should be produced in the clinic (Home collection is not allowed)

• Once the sample is given, the semen sample is mixed with the protective solution and transferred into a vial.

• Temperature of the vial containing the sample is gradually reduced and plunged into the Liquid Nitrogen.

• Later when the sample is required for treatment procedure, the sample is thawed and processed for use.

2) Oocyte cryopreservation:

Egg freezing, is also known as Oocyte cryopreservation, which allows women to preserve their fertility and extend their biological clock, until they are ready to start a family.

Women are generally most fertile during the early teenage till early thirties. But as the age advances, the quality of egg diminishes gradually. Best outcomes for pregnancy are seen in those eggs which are stored at younger age.

Candidates for Egg freezing:

  • Fertility Preservation: When a woman is not ready to carry a pregnancy (due to career, pursue higher education, not having a right partner). This is the best option to ensure that she will have her own eggs available in future.
  • Premature Ovarian Failure
  • Woman with medical diagnosis, like cancer who need chemotherapy or radiation therapy. These treatments can destroy the ability to produce healthy eggs.
  • Woman with conditions like Endometriosis or ovarian tumors, which may cause scarring or compromised ovarian health.
  • Egg donation.

Steps in Egg Freezing Process:

  1. 1) Woman is screened for infectious diseases (HIV, Hep B, Hep C, VDRL).
  2. 2) Written consent for ovarian stimulation, egg retrieval, freezing and storing of unfertilized eggs is taken.
  3. 3) Ovarian Stimulation- Series of hormonal drugs are given to stimulate the ovaries to produce more number of matured eggs.
  4. 4) Egg retrieval- This is an ultrasound-guided procedure done under anesthesia. Each follicles are aspirated and scanned. Normally 10-15 eggs are extracted from the ovaries.
  5. 5) Egg Freezing- The extracted eggs are washed thoroughly and frozen by vitrification method (flash-freezing process- which removes fluid from eggs to prevent ice crystal formation), until future use.
  6. 6) When the decision to conceive is taken, the eggs are thawed and inseminated with sperm (partner’s sperm or donor sperm). The embryos thus formed are transferred into the womb.

The success of the egg freezing program depends on women’s age when her eggs are extracted, freezing and thawing process, women’s age when she attempts to conceive with the frozen eggs and sperm parameters.

3) Embryo cryopreservation:

Embryo freezing, is also known as embryo cryopreservation ,is a well-established routine procedure in fertility clinics, which has helped thousands of infertile couple to have a healthy babies.

In an IVF program, the patients are stimulated to produce many eggs, resulting in many embryos. Due to the risk of multiple pregnancies, very few best quality embryos are transferred (not more than three embryos) and the rest surplus embryos can be frozen.

Benefits of embryo freezing:

  • Embryo freezing allows transfer of fewer embryos in stimulated IVF cycle, reducing the risk of multiple pregnancies.
  • Increases cumulative pregnancy rate, as there might be enough frozen embryos for more than one subsequent cycle.
  • As back-up- If the initial fresh embryo transfer has not resulted in pregnancy, frozen embryos are thawed and transferred in subsequent cycle with minimal medication, less doctor’s visit & surgical procedure and at lower cost.
  • Fertility preservation- for social or medical reasons.
  • Embryo donation.

Embryo freezing process:

In an IVF program, the patients are stimulated to produce many eggs, resulting in many embryos. Due to the risk of multiple pregnancies, very few best quality embryos are transferred (not more than three embryos) and the rest surplus embryos can be frozen.

The embryo freezing procedure has become successful with the advent of Vitrification method. It is an ultra-rapid freezing method, where the embryos are subjected to different concentrations of cryoprotective solutions. These solutions prevent ice crystal formation between the cells. The embryos are then placed in cryostorage device (clearly and permanently labelled for future identification) and plunged into the liquid nitrogen (-196oC). When required, the embryos are thawed using solutions which remove cryoprotectants.

This method has proven to improve frozen-thawed survival rates and pregnancy rates, which is almost as high as the fresh embryo transfer.

© 2018 The Origin International Fertility Center. All Rights Reserved.