Ovarian tissue freezing (cryopreservation)

Your ovaries store the eggs needed to make babies. Eggs are sensitive to radiation and some medicines. This means chemotherapy and radiotherapy can affect your fertility (your ability to become pregnant naturally).

We can remove the outer layer of your ovaries containing immature eggs before treatment using a simple surgery under general anaesthetic. 

We freeze the tissue of your ovaries at very low temperatures to preserve them. This is called ovarian tissue freezing or cryopreservation.

After your main treatment, the ovarian tissue can be put back into your body with a similar surgery. This could restore your periods and ability to become pregnant. 

Who can have ovarian tissue cryopreservation

Ovarian tissue freezing could be suitable for you if you need to start your main treatment urgently and there is no time to have egg and embryo freezing that can take several weeks. 

If your main treatment is very likely to damage the ovaries and all eggs, both egg freezing and ovarian tissue cryopreservation might be appropriate.

Ovarian tissue freezing is the only fertility preservation option if your child is having treatment and they have not gone through puberty (started their period). Egg and embryo freezing involves altering the natural menstrual cycle to help ovaries produce extra eggs. This means it is not suitable for people who have not yet started their period.

Ovarian tissue cryopreservation can also be done in the middle of chemotherapy for people who did not have their eggs collected before starting chemotherapy. Egg freezing cannot be done in patients who had chemotherapy within the last 6 to 9 months.

Success rates for ovarian tissues

By the end of 2017, a total of 318 women had ovarian tissue transplantation procedures. 95% of women reported their period returning. It's estimated that more than 200 babies have been born so far, and the number is constantly increasing. Almost half of these pregnancies were achieved naturally, and the rest needed assisted conception.

Deciding to have ovarian cryopreservation

Your doctor completes a referral form to the assisted conception unit (ACU) for the fertility preservation programme.

At your first appointment, you'll meet one of our experienced fertility doctors who will talk to you about all fertility preservation options that are available at Guy's and St Thomas'.

We'll take a detailed medical history and offer fertility advice based on your circumstances and future cancer treatment, carefully considering the risks and benefits. We also need to make sure you're fit for surgery under general anaesthetic.

The doctor will discuss the procedure in detail. When you make a decision, they help you to complete all the relevant consent forms. These forms are how you give your legal permission (consent).

If you are aged 13 to 16, your parents or carers will be involved in the consent process. This means that they will be part of conversations you have with the doctor and will be asked to sign the consent form.

Tests before fertility preservation

We'll ask you to have a blood test to check if you have hepatitis B, hepatitis C, HIV and HTLV. All patients must have this test because there's a theoretical risk of cross-contamination between samples, although there have been no reported incidences of this. We must have the results of these tests before your samples can be frozen.

We also would need to check you are not pregnant, since tissue preservation cannot be offered to pregnant patients.

Checking your current fertility 

Our doctor will also check your current fertility to help decide what would be most suitable for you. For ovarian tissue cryopreservation to work well, the collected tissue needs to have high number of good quality eggs.

As we get older, the number and quality of our eggs decreases. This means your age can affect your chances of getting pregnant or of having a miscarriage. 

Ovarian reserve means the approximate number of eggs left in your ovaries. We can estimate if the number of your stored eggs is low, normal or high. Ovarian tissue cryopreservation is not suitable for older patients, or people with a very low ovarian reserve. 

We check ovarian reserve using a blood test to measure your hormone levels and an ultrasound scan. 

Surgery to collect ovarian tissue

We collect tissue during a short procedure called a laparoscopy which is a day surgery. This means you will go to hospital and leave on the same day, and do not stay overnight. 

The surgery is laparoscopy (keyhole) which means that very small incisions are made in your belly button and lower tummy. This is done using general anaesthetic so you will not feel anything.

The surgeon inserts a laparoscope (a small camera) into your abdomen (tummy). The surgeon examines both ovaries and removes one. Sometimes, the surgeon removes only part of one, or parts from both ovaries. This depends on your history and what permission you've given before treatment.

After surgery, you can usually go home on the same day. You should be able to start your main treatment shortly after, sometimes the next day if necessary.  

Once you have recovered from your main treatment, if you stop having regular periods, your ovarian tissue can be transplanted back into your body with a similar surgery. 

Storing and freezing the tissue

The tissue is taken to the assisted conception unit (ACU) where it's processed for freezing. The tissue is cut into thin slices and frozen in a number of separate vials at a very low temperature. Very small amounts of tissue will also be sent to the histopathology lab to check it's healthy.

Risks of collecting and freezing ovarian tissue

Ovarian cryopreservation is a relatively new procedure. Until today, a much smaller number of babies are born from this procedure compared with freezing eggs or embryos.

Risk of ovarian tissue containing cancer cells

One potential concern is ovarian tissue containing cancer cells that could be reintroduced into the body once transplanted back. Some cancers such as leukaemia can spread into the ovaries. We screen some of the ovarian tissue for cancer cells in our histopathology department before storage. If the pathologist finds abnormal cells, we might not be able to store or use the rest of the tissue for fertility preservation. A 'normal' result of this screen cannot guarantee that the rest of the tissue is free of abnormal cells. However, there is no evidence that suggests transplantation of cryopreserved ovarian tissue causes the original cancer to return. 

In patients with leukaemia, we do more tests on ovarian tissue before deciding if it's safe to put them back.

Risks of a laparoscopy

Laparoscopy is a commonly performed procedure and serious complications are rare. Risks include infection, damage to internal organs or bleeding as a result of the laparoscopic instruments. The chance of these complications is about 1 in 500. These complications might delay your cancer treatments.

Risk of cryopreservation

Ovarian tissue may be damaged during freezing, storage or transplantation, and not work to restore your fertility. 

Chances of pregnancy complications or birth anomalies

It's not known if cryopreservation affects how likely it is that you will have a complication in pregnancy or if your baby will be born with a condition. There are no reports to suggest that children born from ovarian tissue have a different chance of this. 

If you no longer need your tissue

Your stored tissue can never be used for treatment of any other patient. Any ovarian tissue not used at the end of the storage period, or at the time of your request to withdraw the storage, must be disposed in accordance with the Human Tissue Authority Act. You'll also have the opportunity to donate the tissue for ethically approved research if you want to.