Egg Freezing

Sperm, Egg and Embryo Storage

What is egg freezing?

Freezing or cryopreservation is the process of storing cells or tissue at a very low temperature in liquid nitrogen. Eggs are frozen using a fast-freezing technique called vitrification. Eggs stored in this way can be thawed at an appropriate time in the future and used in an IVF-ICSI cycle.

In order to obtain a good number of eggs for freezing, you will be given fertility hormones for around two weeks to encourage your ovaries to produce eggs. This is called ovarian stimulation and is very similar to the first part of an IVF treatment cycle.

Why do women freeze their eggs?

There are many reasons for women to freeze eggs. Most women who freeze their eggs do so ahead of treatment for cancer or other medical conditions that may affect their fertility. Some women choose to freeze eggs if they are not yet ready to have a family and are concerned about the natural decline in fertility with age (sometimes referred to as social egg freezing). IVF patients may choose to freeze eggs during an IVF cycle if for ethical or religious reasons they wish to limit the number of embryos created. Eggs can also be frozen during an IVF cycle if there is not enough sperm for insemination. Finally, eggs can be frozen for storage and donation to others.

What will happen before my treatment starts?

First of all you will see a specialist fertility doctor who will discuss your treatment options with you. They may also recommend some investigations, including a blood test called an anti-müllerian hormone (AMH) test. The AMH test allows us to see how you are likely to respond to the fertility hormones given as part of the egg freezing treatment, and allow us to tailor the hormone dose to optimise your cycle.

We will also perform blood tests for HIV, Hepatitis B and Hepatitis C. These tests are required for all patients to minimise the risk of cross contamination in the laboratory and in gamete/embryo storage vessels. If you have a positive test, we will provide you with counselling and referral to a specialist for advice about your future health. These tests need to be done prior to you starting any treatment.

Before you choose which treatment to have or sign any consent forms, you are entitled to see the counsellor to discuss the implications of treatment. We particularly encourage counselling for oncology patients or patients seeking to freeze eggs for social reasons.

Please ask a member of staff if you would like to arrange a counselling appointment. Occasionally it may not be possible to see the counsellor before giving consent, for example if your fertility preservation treatment is very urgent. In this case, we can arrange a counselling appointment for after you have completed the consent forms in the knowledge that you can change or withdraw your consent at any time.

Medical consultation
At this appointment one of our specialist fertility doctors will discuss the proposed treatment, including the risks and chances of success if you were to use your frozen eggs in the future. If you are happy to go ahead, this is the appointment where you will sign your consent forms.

Nurse consultation
Your next appointment will be with one of our specialist fertility nurses. The purpose of this appointment is to discuss the treatment in even more detail. You will be given an individualised treatment plan, arrange a date to commence treatment and be trained in how to give yourself the fertility hormone injections, which are given using a very small needle into your tummy or your thigh. The nurse will check your consent forms with you and make sure everything is in order before treatment starts.

What will happen during my egg freezing treatment cycle?

1. Stimulating your ovaries
Most often treatment starts with the first day of your period. When you have started your period, give us a call and we will book you in for an internal ultrasound scan to check there is nothing wrong that might affect the cycle. After the scan the nurse will give you instructions for starting your ovarian stimulation using a hormone called follicle stimulating hormone (FSH). FSH is produced by your body during a normal menstrual cycle to stimulate the ovaries to mature just one egg per month. The dose you will be prescribed should ensure your ovaries are sufficiently stimulated to mature all the eggs that are available that cycle.

Occasionally for oncology patients treatment may start in the middle of your menstrual cycle and your nurse will give you specific instructions in this case.

2. Monitoring your treatment cycle
Eggs develop in small fluid filled sacs within the ovary called follicles, which are easily visible on ultrasound scan. When you have been taking the injections for about a week, we will ask you to come in for a scan so that we can monitor how well your ovaries are responding to the FSH. We do this by measuring the size and number of the follicles in the ovaries. At this stage we may alter the dose of FSH depending on how you are responding. Scans then continue every 2-3 days until there are a sufficient number of large follicles. Occasionally if the number of developing follicles is very low and you are freezing eggs for social reasons, we may recommend that you cancel the treatment cycle and try again in another month. From starting your FSH injections to taking your trigger is normally around 10 to 14 days.

3. Triggering ovulation
When the scan shows that you have a number of follicles of 17mm or more we'll ask you to take a final trigger injection at a specific time in the evening. The trigger injection prompts the eggs to begin the final stage of their maturation process. This trigger injection has to be taken at the correct time, as your eggs will be ready for collection approximately 36 hours later.

4. Egg collection
You'll be asked to come to the clinic about 36 hours after taking your final injection. You will see an anaesthetist who will give you sedation medication to ensure that you don't feel any pain during the egg collection procedure. We will collect your eggs by passing a fine needle through the vaginal wall into each of your ovaries using ultrasound guidance. The fluid contained in each follicle is sucked into the needle and transferred into a tube and passed to one of our embryologists. The embryologist will then count the number of eggs that have been retrieved and put them in an incubator in our laboratory. The eggs will be frozen the same day. The egg collection procedure normally takes around 15-30 minutes.

You will rest in the clinic for a short while following the procedure, after which you may go home. You will be a little drowsy from the sedative and must be taken home by a friend or family member. You will need to take the day off work and you must not drive for 24 hours.

End of treatment
As soon as you have had your eggs collected, the cycle has finished. We will keep in contact with you to check that you are feeling ok after the procedure and let you know how many eggs were frozen and their maturity. You will start your period around a week after your egg collection procedure.

What are the side effects/ risks of treatment?

FSH injections can result in temporary weight gain due to salt and water retention. You may experience headaches, bloating, a sensation of extreme fullness or discomfort very similar to pre-menstrual tension. These effects should only last for the duration of your treatment and should return to normal following your period. You may also experience soreness and bruising at the site of the injections, which should subside when you stop the injections.

Occasionally, some women are very sensitive to FSH and produce a large number of follicles. These women are at greater risk of complications, including ovarian hyperstimulation syndrome (OHSS). OHSS is the most serious side effect of treatment and occurs in about 1 in 100 women. The symptoms of OHSS include abdominal pain, abdominal swelling, shortness of breath, nausea and possibly vomiting, and a reduction in urine output. In the presence of severe symptoms, hospitalisation may be necessary. Due to the seriousness of the problem, prevention is better than cure. Your progress will be monitored closely and treatment will be stopped if any adverse symptoms occur.

There is a very small risk (about 1 in 2000) of bleeding or infection as a result of the egg collection. However, a small amount of vaginal bleeding is quite normal and will settle down after a day or two.

There is a higher risk of pregnancy if you have unprotected sexual intercourse after egg collection and before your next period arrives. This is because, although we endeavour to collect all your eggs, occasionally one or two may remain which could increase your chance of getting pregnant.

There is a theoretical risk of viral (e.g. HIV, Hepatitis B & C) cross-contamination between samples that are stored in liquid nitrogen. The actual risk is unknown and although there have been no reported incidences of such cross-contamination between frozen eggs, all patients are now required to be screened for HIV and Hepatitis B & C before we freeze any eggs or embryos. Patients who test positive for HIV, Hepatitis B or C positive cannot store their samples in containers alongside samples from patients who have screened negative.

If you are freezing eggs ahead of treatment for breast, ovarian or other female-specific cancers, your fertility doctor may prescribe additional medication to keep your oestrogen levels from getting very high.

How many times can I freeze eggs?

If you are freezing eggs ahead of urgent cancer treatment, it may not be possible to have more than one cycle of egg freezing. However, if you are freezing eggs for social reasons, it may be recommended to have more than one cycle, particularly if you have fewer than 8-10 mature eggs stored from your first cycle. Your fertility doctor will discuss this with you.

How long can I store my eggs for?

Most patients can consent to store their eggs and embryos for up to 10 years. If you are storing eggs for fertility preservation for medical reasons, for example if you are about to undergo treatment for cancer, you may consent to store your eggs and embryos for up to 55 years.

For all patients, your eggs and embryos can only be stored for longer than 10 years if you or your partner are certified prematurely infertile by a medical practitioner. You must contact us before the 10 year expiry if you wish to keep your samples in storage. If you meet the criteria, your case will then be reviewed every 10 years up until the legal maximum storage period of 55 years. If you fail to contact CFC to request a review of your case, then your eggs will be discarded when your existing storage consent expires.

It is important to understand that if you die or become mentally incapacitated during that time that your eggs are in storage, your eggs cannot be used in treatment unless a specific written consent for this has been provided. This may involve the completion of surrogacy or donation consent forms. If this is an option you wish to consider, please contact us at the earliest opportunity to arrange a counselling appointment to discuss the implications of this further.

You can withdraw or change your consent at any time up until the point at which eggs or embryos have been used in treatment or training. This is particularly important if you and your partner split up and you have consented to your partner being able to use your eggs/ embryos in treatment in the event of your death or mental incapacity. If you wish to withdraw or change your consent, please contact the clinic so that we can arrange for the necessary forms to be completed.

What treatment is required if I want to use my eggs?

If you want to use your stored eggs, they will be thawed and inseminated with partner or donor sperm by ICSI (intracytoplasmic sperm injection), where one sperm is injected into each mature egg. Frozen eggs are not suitable for insemination by conventional IVF. The fertilised eggs (embryos) will be cultured in the lab for up to five or six days. One or two embryos will be transferred to your uterus. Any remaining good quality embryos can be frozen for treatment at a later date. You will be given more detailed information about IVF-ICSI at the time, or please ask for a copy of our IVF information sheet.

It is possible that not all the eggs will survive thawing, or ICSI, and in rare cases no eggs will survive. There is also a risk that the eggs that do survive might not fertilise or the embryos may not develop normally.

What is the chance of success?

Your own chance of success will be influenced by a number of factors and may be different to the overall results. On average, the number and quality of eggs produced in an egg freezing cycle reduces with age, and the chance of a live birth from frozen-thawed eggs therefore also decreases with age.

So far only a few patients who have frozen their eggs have used them in treatment, therefore we do not yet have enough information to provide any pregnancy rates.

Is treatment available on the NHS?

NHS funded treatment is available for some women freezing eggs before cancer treatment, but the amount of funding and the criteria for treatment varies between different Health Authorities. Again, when/ if you need to use the eggs in treatment in the future, NHS funding is not guaranteed. These issues will be discussed with you at the time of referral. There is no NHS funding for patients freezing eggs for social reasons.

What is the cost of treatment?

If you are not eligible for NHS treatment or do not wish to wait for treatment, you may self-fund treatment. Charges include all treatment consultations, egg freezing procedures and counselling. If treatment is cancelled before oocyte retrieval, there may be a refund and this information will be provided to you at your nurse appointment. Payment is required before you start your treatment cycle. Annual storage fees apply after the first year of storage.

Loss of contact/ failure to pay storage fees
When you consent for your eggs to be stored at our centre you enter into an agreement with us that you will keep your contact details up to date and pay any storage fees required. The HFEA storage consents that you complete allow us to legally store your eggs; however they do not mean that we are legally obliged to continue storing them if you break the terms of your agreement with the clinic.

It is vitally important that you keep us informed of any changes to your contact details and pay your storage fees promptly. If we lose contact with you, or you do not pay your storage fees, we reserve the right to discard your stored eggs.

Where can I get more information?

We hope that this information leaflet has given you all the information that you require before your treatment. Please do not hesitate to contact us if you need further information or if you do not understand anything. We welcome any suggestions you may have on improving our leaflets.

The staff of the clinic are always available should you require any further information and this includes 24 hour out-of-hours cover should you have a more urgent medical problem.

A list of national and local Infertility Support groups is available in the clinic.

Further information can be also obtained from the Human Fertilisation & Embryology Authority (HFEA). Please visit for information on infertility, treatment and advise on how to choose your fertility clinic.


Mr Brook and the team were friendly, direct and very efficient. Overall an excellent service.

Fertility Testimonials
Fertility Testimonials


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