How Does Egg Freezing Work?

Who is egg freezing for?

Let’s get to the first step.

So, is egg freezing really for you? 

In fact, it can be a mix of medical and social reasons.

Here are some reasons why women go for egg freezing:

Medical reasons such as chemotherapy

‍Women who have been recommended chemotherapy can undergo egg freezing funded by the NHS to preserve their fertility. This helps protect their eggs from the harmful effects of chemotherapy. Egg freezing allows you to preserve your eggs before starting treatment, so you have the option to conceive using your own eggs after recovery.

Focus on career and plans

‍Maybe you're focusing on your career or education now, but know you eventually want children. Egg freezing allows you to preserve your fertility when your eggs are genetically healthier. Fertility naturally declines with age, so freezing your eggs in your 20s or 30s offers the best chance of success with future fertility treatments.

Personal reasons

‍You may have not found “the right partner” yet, or maybe you’re a woman in a same-sex relationship, wishing to have a baby in the future. Regardless, both are absolutely valid reasons to freeze your eggs.

Infections or health concerns

‍Health issues such as stage 3 or 4 endometriosis can block fallopian tubes and harm ovaries, leading to infertility. In such cases, you may need advanced treatment such as surgery to remove large cysts or scar tissue. Before this process, it’s recommended to freeze eggs during the early stages of endometriosis, which allows you to conceive with your own eggs after recovery.

Have a low ovarian reserve

‍This is when the ovaries have a lower-than-usual number of eggs. This can happen naturally due to age or be caused by underlying medical or genetic conditions. Pooling and freezing your eggs in this case, before your egg count declines further, may serve as a backup option when you’re ready to start trying! 

How does egg freezing work?

The egg-freezing process typically starts with doctor consultations and deciding which tests are needed to evaluate your ovarian reserve. Once the green signal is given, here are the steps that follow:

1. Monitoring (baseline assessment)

You may be asked to visit the doctor during day 2 or 3 of your menstrual cycle. At this stage, you undergo blood tests to assess hormone levels like oestrogen and follicle-stimulating hormone (FSH). FSH helps stimulate egg growth. 

Additionally, you also undergo an ultrasound to measure your antral follicle count. Antral follicles are small fluid-filled sacs in the ovaries that each contain an immature egg. The number of antral follicles can be an indicator of your remaining egg reserve.

2. Ovarian stimulation

Once the assessment is done, you are prescribed medications to stimulate the ovaries to develop multiple mature eggs at once, to increase the number of eggs available for freezing. These medications are typically injectable fertility drugs and will be monitored and adjusted by your doctor throughout the process.

The medications include FSH and LH for about a week or two, to stimulate your ovaries to produce eggs. Around halfway through the cycle, gonadotropins are started to prevent ovulation from taking place too fast.

3. Trigger shot

Once the ultrasound shows the eggs have reached a certain size (16-22mm), these are indicative of a mature egg. It’s also important to remember that the follicle and egg yield may differ, AKA, the number of follicles may not always be equal to the number of mature eggs retrieved. 

At this stage, a final injection (trigger shot) is given. This trigger shot contains a surge of human chorionic gonadotropin (hCG), a hormone that mimics the body's natural ovulation signal. 

The timing of the trigger shot is crucial to ensure the eggs are mature enough for retrieval but haven't yet ovulated. Hence, it’s done at precisely 36 hours before egg retrieval.

4. Egg retrieval

This is a minor surgical procedure performed under anaesthesia to retrieve the mature eggs directly from the ovaries. 

Gynaecologists use a transvaginal ultrasound-guided needle. While the ultrasound creates a live image of the ovaries, the doctor guides the thin needle through the vagina and punctures the follicles to aspirate the eggs. The needle is connected to a suction pump for aspiration and to a lab tube containing media.  The journey during egg retrieval looks something like this:

This tube is placed in a heating block set to body temperature. This is to ensure that the eggs, once outside the body, aren't exposed to major temperature changes.

5. Separating the mature eggs

Now, it’s the embryologist's turn. 

In a way, it's like hide and seek. The eggs, once retrieved from the body, come with a layer of cells around them known as cumulus cells. 

The embryologist's job is to use a stripping pipette and gently remove the cells around the egg.

This helps us understand whether the egg is mature or not. Until then, the cumulus cells cover the egg making it quite tricky to know the maturity (cloudy vision much? 😶🌫️).

6. Egg Freezing (vitrification)

Once the mature eggs are identified, the media for freezing eggs which is already prepped is taken out. 

This is known as vitrification media, which helps rapidly freeze the eggs. The media is a special cryoprotectant solution to protect the eggs from ice crystal formation during freezing. 🥶 

Traditional freezing methods back then were slower and were more prone to egg damage. Vitrification offers a much faster freezing process, minimising this risk. 

The frozen eggs are then stored in tiny devices called cryolocks and placed in liquid nitrogen tanks for long-term storage.

Where are my frozen eggs stored?

Your frozen eggs are stored securely in a special container within a liquid nitrogen tank. Liquid nitrogen is an extremely cold substance (-196°C) that suspends the growth of the eggs, pausing their development. 

The tanks are continuously monitored by alarms and refilled regularly to ensure the eggs remain frozen and safe. Clinic staff also perform regular maintenance checks on the tanks to ensure proper functioning.

Talk about an egg-freezing patrol! 🚨

How can I used my frozen eggs?

When you're ready to use your frozen eggs, you'll simply need to notify the clinic. 

This is followed by doctor's appointments to monitor your hormone levels and get you prepared for an ICSI cycle. 

On the lab end, they will thaw or warm the eggs using a warming solution to perform ICSI. 

“It’s important to remember that when you freeze eggs, you commit to ICSI as the outer membrane of the egg becomes quite hard after freezing, making it hard for sperm to enter via conventional IVF” - Navya Muralidhar

ICSI is done by selecting a single sperm and directly injecting it inside the egg to fertilise. The resulting embryos are then monitored and then transferred to the uterus either via a fresh or frozen embryo transfer. 

Also read: Should I freeze eggs or embryos?

Cost of egg freezing in the UK

The cost of egg freezing can vary depending on factors like your location, clinic fees, and medication requirements. However, it’s typically broken down into stages such as:

1. Initial consultation with a fertility specialist.
2. Blood tests and ultrasounds for monitoring.
3. Medications used for ovarian stimulation.
4. Egg retrieval procedure and anaesthesia.
5. The freezing process (vitrification) and storage costs.

Think egg freezing, think Amilis

Navigating your egg-freezing journey from start to end can seem like a lot of checklists. 

From researching to finding a clinic, a doctor, a test to take… the list goes on. 

But, as people who went through a similar journey, we made a mission to keep that checklist down to just one task. 

To have our stellar team take care of the navigating process for you! 

From all the resources on egg freezing to a personalised quiz to help you get started, we’re by your side through it all! 

We’re set out to make egg freezing easier for you! You've got this!