Ovum Cryopreservation


Egg freezing, or oocyte cryopreservation, is a procedure in which the eggs (oocytes) of a woman are extracted, frozen, and stored as a technique to maintain in reproductive capacity in a woman of reproductive age. Unfertilized eggs obtained from ovaries are frozen and preserved for later use. Frozen egg is thawed, mixed with sperm in a lab and then implanted in a uterus (IVF). Over the past few years, oocyte cryopreservation has progressed dramatically, with increased overall performance of eggs surviving the freezing process.

Based on your needs and reproductive history, the doctor will help you understand how egg freezing functions, the possible risks and whether the fertility preservation approach is right for you.

Why Ovum Cryopreservation

If you’re not ready to get pregnant now but want to try to make sure you can get pregnant later, then egg freezing might be an option.

Egg freezing does not require sperm, as with fertilized egg freezing (embryo cryopreservation), since the eggs are not fertilized until they are frozen. However, just as with embryo freezing, you will need to use fertility drugs to help you ovulate so that multiple eggs will be developed for retrieval.

You may consider egg freezing if:

  • You have a disease or circumstance that can affect your fertility: These could include sickle cell anaemia, autoimmune diseases such as lupus, and gender diversity, such as being transgender.
  • You need treatment for cancer or other diseases that can affect your ability to get pregnant: Your fertility can be affected by medical procedures such as radiation or chemotherapy. It could enable you to have biological children later if you freeze eggs before treatment.
  • You wish to preserve younger eggs now for potential use: At a younger age, freezing eggs could help you get pregnant when you're ready.

To try to conceive a child with sperm from a partner or a sperm donor, you can use frozen eggs. The embryo can also be implanted in another person’s uterus to carry the baby (gestational carrier).

Ovum cryopreservation process

You are likely to have some blood screening tests before starting the egg-freezing process, including:

  • Ovarian reserve testing: Your doctor can measure the concentration of follicle-stimulating hormone and estradiol in your blood on day three of your menstrual cycle to determine the quantity and quality of your eggs. Results will help predict how fertility medicine will react to your ovaries. 
    To get a clearer image of ovarian function, another blood test and an ultrasound of the ovaries may be done.
  • Infectious disease screening: You will be screened for some infectious diseases such as HIV and hepatitis B and C.

There are multiple steps to egg freezing — ovarian stimulation, egg retrieval and freezing.

Ovarian stimulation

Instead of the single egg that typically develops monthly, you’ll take synthetic hormones to stimulate your ovaries to produce multiple eggs. Drugs that might be required include:

  • Medications for ovarian stimulation: Medications such as follitropin alfa or beta (Follistim AQ, Gonal-f) or menotropin (Menopur) may be injected.
  • Medications to prevent premature ovulation: Injectable gonadotropin-releasing hormone agonists such as leuproline acetate (Lupron) or gonadotropin-releasing hormone antagonists such as cetrorelixx may be prescribed by your doctor (Cetrotide).

Your doctor will monitor you during treatment. To measure your response to ovarian-stimulation medications, you will have blood tests. As follicles develop, estrogen levels typically rise, and progesterone levels stay low until after ovulation.

In order to track the development of fluid-filled sacs where eggs mature- follow-up visits will often include vaginal ultrasound- a technique that uses sound waves to produce a picture of the inside of your ovaries (follicles).

An injection of human chorionic gonadotropin (Pregnyl, Ovidrel) or another drug may help the eggs mature when the follicles are ready for egg retrieval, normally after 10 to 14 days.

Egg retrieval

Egg retrieval is performed under sedation, usually in your doctor's office or a clinic. Transvaginal ultrasound aspiration is a common approach, during which an ultrasound probe is inserted into your vagina to locate the follicles.

A needle is then directed through the vagina and into a follicle. To extract the egg from the follicle, a suction device which is attached to the needle is used. Multiple eggs may be removed and studies indicate that the more eggs collected— up to 15 per cycle — the higher the chances of birth.

You may have cramps after egg retrieval. For weeks, feelings of fullness or discomfort can persist because your ovaries stay swollen.


Your unfertilized eggs are cooled to sub-zero temperature shortly after they are harvested to protect them for future use. The development of an unfertilized egg makes it a little harder to freeze and lead to a healthy pregnancy than does the development of a fertilized egg (embryo).

The method most widely used for egg freezing is called vitrification. With rapid cooling, high concentrations of substances that help prevent the formation of ice crystals during the freezing process (cryoprotectants) are used.

After the procedure, usually, within a week of egg retrieval, you can resume daily activities. To prevent an accidental pregnancy, avoid unprotected intercourse.

Benefits of cryopreservation

  • Egg freezing pauses your biological clock: An average woman is born with about three million eggs in her ovaries. Some of those eggs hit a certain point of maturity, stop developing, and die off. With age eggs begin to decline. When she is in her early twenties, the number of eggs in the ovaries of a female is most favourable for reproduction. It helps preserve your ability to have biological children later because egg freezing harvests eggs from your ovaries for long-term cryopreservation in a sterile laboratory environment.
  • Egg freezing helps preserve egg quality: Declining egg numbers are not the only thing that you need to think about as you age. As time passes, the quality of your eggs is also more likely to suffer. If you plan to become pregnant in your late thirties or early forties, preserving your eggs is an excellent way to preserve their dignity and ensure that you have healthy eggs available.
  • Egg freezing puts you in control: In your early adult years, egg freezing helps you to concentrate on your life goals without experiencing the relentless worry of a ticking biological clock. It will remove your fear of your potential fertility and leave you feeling inspired.


Egg freezing carries various risks, including:

  • Conditions related to the use of fertility drugs: Usage of injectable fertility medications, such as synthetic follicle-stimulating hormone or luteinizing hormone to induce ovulation, will rarely cause the ovaries to swell and become painful shortly after ovulation or egg recovery (ovarian hyperstimulation syndrome). Abdominal pain, bloating, nausea, vomiting and diarrhoea are some signs and symptoms.
  • Complications of egg retrieval process: Bleeding, inflammation, or damage to the intestines, bladder, or blood vessels is occasionally caused by the use of an aspirating needle to extract eggs.
  • Emotional risks: The freezing of eggs may bring hope for a potential pregnancy, but no guarantee of success.

If you use your frozen eggs to have a child, the chance of miscarriage will be mainly based on your age at the time your eggs were frozen. Older women, having older eggs, have higher miscarriage rates.

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