Freezing gametes for future use

Freezing (cryopreservation) involves storing samples of your reproductive cells (gametes) at a very low temperature in liquid nitrogen.

Gametes stored in this way can be thawed out in the future for fertility treatment.

Before fertility preservation, you’ll need to be tested for HIV and hepatitis B and C.

Your reproductive cells will also be analysed so we know the quality, as this might affect your chances of having a baby in the future.

Consultation to discuss treatment

Before we can store your samples, you have a consultation with a doctor or nurse in the fertility unit to talk about storing your gametes, and to complete the relevant consent forms. We'll ask you to produce a sample, complete consent forms, and have a blood test.

We know that this process might feel difficult for you, but we are here to support you, and will be happy to answer any questions you have.

We'll give you personalised guidance based on your circumstances, to help you make informed decisions and explore the most suitable options for preserving fertility.

Tests for HIV and hepatitis

In theory, there’s a risk of viral cross-contamination between samples that are stored in liquid nitrogen.

There has never been a report of this happening but, because of the theoretical risk, you must be screened for HIV and hepatitis B and C.

We cannot freeze any samples until we’ve had the results of these tests.

Our assisted conception unit currently cannot offer storage if you test positive for HIV or hepatitis B or C at this time, but we will be able to advise where this service is available.

Giving a sample

A gamete sample is usually produced by masturbating. There are facilities in the fertility unit, where you can produce a sample in a separate, private area.

We understand that this might be embarrassing and difficult for some people, but we’re here to support you and answer any questions you have.

Sometimes it is possible to produce a sample at home, using the sterile pot provided, and bring it to the fertility clinic. This is only possible if you can get the sample back to the clinic within 1 hour.

Analysing the quality of your gametes

Analysis will tell us the quality of your gametes. Some people, especially people on hormone therapy, might have lower quality or quantity of reproductive cells. 

Even if the quality is poor, you might still want to store samples for future use. Some fertility procedures only require a small number of viable or ‘good’ cells to fertilise eggs. This includes intra-cytoplasmic sperm injection (ICSI) where a single sperm is injected into each egg. 

The doctor can talk to you more about your options when the results of the analysis are available.  

Future fertility treatment

When you want to use your reproductive cells in the future, you may choose to do so through the fertility unit at Guy's and St Thomas', or elsewhere. Your sample can be used in simple insemination procedures, such as intra-uterine insemination (IUI), or more complex assisted conception treatments, such as IVF or ICSI.

We'll give you advice about the best procedure depending on the quality and the quantity of the reproductive cells, and your preferred way of building a family.

How long samples are stored for

The statutory (legal) maximum time period for storing gametes for medical reasons is 55 years.

Our policy is for you to give permission (consent) for us to store gametes for 10 years. If you want to continue to store your gametes after this time, you must contact us in writing and one of the doctors will assess if there are still medical grounds to continue storage of your gametes.

It’s very important that we can keep in regular contact with you. You might want to store gametes for several years, so it’s possible that you will move during that time. It’s your responsibility to make sure we are told of any change in your circumstances, such as a new address, phone number or a new partner.

If we cannot contact you to find out if you want us to continue to store your gametes, by law samples have to be destroyed.