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Understanding the Egg Freezing Journey: A Comprehensive Guide

Egg freezing, or oocyte cryopreservation, is a method to store a woman’s eggs for future use. This is sometimes referred to as “fertility preservation”.

Eggs harvested from the ovaries are frozen and stored in special storage vessels. A frozen egg can be thawed, combined with sperm in the laboratory and incubated at the right conditions to develop into an embryo, which will then be implanted in the uterus.

At Bridge Clinic London, our doctors and embryologists can help you understand how egg freezing works, the potential risks and whether this method of fertility preservation is right for you based on your needs and your medical history.

Why consider egg freezing?

Consider egg freezing if you are not ready to become pregnant now but want to try to get pregnant later.

You might consider egg freezing if:

  • You have a condition or circumstance that can affect your fertility. These might include sickle cell anaemia, autoimmune diseases such as lupus, and gender diversity, such as being transgender.
  • You need treatment for cancer or another illness that can affect your ability to get pregnant. Certain medical treatments, such as radiation or chemotherapy, can harm fertility.
  • You wish to preserve younger eggs now for future use. Freezing eggs at a younger age might help you get pregnant when you are ready later. 

You can use your frozen eggs to try to conceive a child with sperm from a partner or a sperm donor. A donor can be known or unknown. The embryos can also be transferred into your uterus or another person’s uterus to carry the pregnancy (gestational carrier).

  • Egg freezing can provide hope for a future pregnancy, but success is not guaranteed.

Egg freezing process explained

If you are a patient undergoing egg freezing, you will need to use fertility medications to make you grow a number of follicles so that you will produce multiple eggs for retrieval. This is known as ovarian stimulation.

The ovarian stimulation phase

You will take medication to stimulate your ovaries to produce multiple eggs — rather than the single egg that typically develops monthly. The eggs are produced inside follicles within the ovary. The follicle growth is monitored at the clinic by ultrasound scans. When the follicles reach the right size (usually after 10-14 days), a final medication is administered to help the eggs mature.

Egg retrieval

Egg retrieval is done under sedation at the clinic. Follicles will be visualised using transvaginal ultrasound scanning, and the fluid in the follicles is aspirated using a suction needle. The embryologists then check this fluid under the microscope to retrieve the eggs.

After egg retrieval, you might have some cramping. Feelings of fullness or pressure might continue for weeks because your ovaries remain enlarged.

The freezing procedure

Shortly after your eggs are harvested, they are cooled to subzero temperatures to preserve them for future use. The makeup of an unfertilised egg makes it a bit more difficult to freeze and lead to a successful pregnancy than does the makeup of a fertilised egg that has developed further (embryo).

Post freezing: The vitrification process

The process most commonly used for egg freezing is called vitrification. High concentrations of substances that help prevent ice crystals from forming during the freezing process (cryoprotectants) are used with rapid cooling.

Using your frozen eggs

When you are ready to use your frozen eggs, they will be thawed and injected with sperm to create embryos. The embryo(s) will then be transferred into the uterus. This is known as “embryo transfer”. 

The method used for inseminating the eggs is Intracytoplasmic Sperm Injection (ICSI), where a single sperm is injected directly into each thawed egg.

The likelihood of becoming pregnant following egg thawing and embryo transfer depends on the woman’s age at the time of egg freezing. The older you are at the time of egg freezing, the lower the likelihood that you’ll have a live birth.

Potential risks of egg freezing

The egg freezing process, like any medical procedure, carries various risks, including:

  • Some or all the eggs may not survive the thawing process.
  • Eggs that survive the thawing may not produce viable embryos.
  • Conditions related to the use of fertility medications. Rarely, the use of injectable fertility drugs can cause your ovaries to become swollen and painful soon after ovulation or egg retrieval (ovarian hyperstimulation syndrome). Signs and symptoms include abdominal pain, bloating, nausea, vomiting and diarrhoea. Even rarer is the possibility of developing a more severe form of the syndrome that requires hospitalisation and can be life-threatening.
  • Egg retrieval procedure complications. Rarely, using an aspirating needle to retrieve eggs can cause bleeding, infection or damage to the bowel, bladder or blood vessel.