Cryopreservation

Embryo cryopreservation

During an IVF treatment cycle, the ovaries are stimulated to produce more than one egg to maximise the chance of success. Since no more than one or two embryos are usually transferred during a treatment cycle, there may be spare embryos remaining after treatment. It is possible for these spare embryos to be frozen, stored, and transferred during a subsequent treatment cycle with the advantage of fewer drugs and a much simpler treatment.

The procedure

Any embryos remaining after the process of embryo transfer are assessed for their suitability for cryopreservation. Embryos of suitable quality, and those at the correct stage of their development on the day of transfer, i.e. those most likely to survive the cryopreservation process, are selected for cryopreservation.

Frozen embryos may be kept in storage for up to ten years (the statutory storage period) although in some specific circumstances they may be stored for longer than this. There will usually be a fee for the on-going storage of cryopreserved embryos and your clinic will make you aware of this before you consent to this procedure.

Sperm freezing is available for those people who are having sperm removed surgically from the testis, for people who may feel that there will be problems providing a sample on the day of treatment, for patients requiring chemotherapy who may wish to freeze sperm beforehand and for patients that are intending on having a vasectomy and wish to store samples of sperm frozen prior to this procedure.

Following a referral for sperm storage, an appointment will be made to see one of the Embryologists. All patients wishing to freeze their sperm are required to undergo routine blood screening for HIV 1 and 2, Hepatitis B and C prior to the storage of their samples.
Facilities are provided at each site to produce the samples and each sample is stored using strict, unique identifying codes.

At the appointment, HFEA consent forms and additional consent forms will be completed and information given regarding storage. Please allow at least half an hour for this appointment. Sperm may be frozen for a limited period of time (3 months) as a backup sample or it may be frozen for a longer period of time with an annual storage fee being payable.

Sperm Cryopreservation

The statutory storage period for sperm storage is ten years. Samples may be stored longer than this if you or your partner have, or are likely to become, prematurely infertile. If you think this may apply to you please discuss this with your centre. Storage can only be extended for longer than ten years with the agreement of a medical practitioner and provided all fees have been met.

You may consent to any period of time up to the statutory storage period. This may depend on your long term plans and discussions you may have had with a partner, so you may wish to consent to a shorter period, for example five years. Please remember that the arrangements you need to make for payment are separate from your consent to storage so we reserve the right to remove samples from storage if storage fees have not been paid.

The survival of frozen and thawed sperm varies between individuals and between samples. This means that during freezing, there is a possibility of the deterioration of the samples. This is due to the extremes of temperature involved during the freezing procedure. This means that there can be no assurance that sperm will be viable on thawing although we will always try to give you a realistic idea of its success. Depending on the quality of the sample, there may be enough sperm stored for between one and three treatment cycles.

It is important to stress that a pregnancy cannot be guaranteed from the use of cryopreserved sperm and it is likely that the female partner may require some form of assisted conception treatment in order to maximise the chance of pregnancy. This treatment may be fairly straightforward requiring minimal intervention. Alternatively, it may be that highly sophisticated techniques will need to be employed which are complex and can be quite stressful for both partners. The type of treatment will depend on the initial quality of the semen sample and this will be discussed at the first appointment, and a patient information brochure made available if necessary. There is currently no evidence of lack of safety for the female partner or children resulting from the use of frozen-thawed sperm.

Sperm samples are stored in liquid nitrogen dewars. The dewars are connected to an alarm system which will notify us of a problem with the level of liquid present in the dewar, however there is a remote possibility of the loss of stored material due to unexpected mechanical breakdowns, or due to incidents beyond our control. It is also possible that there may be a small risk of cross contamination from other samples in the storage dewar due to unknown pathogens or viruses.

We will write to you each year (after the first two years of storage) to keep you informed about your samples and to request payment of storage fees. You will be given the option of either continuing the storage, or you can request that the samples are removed from storage. If samples are kept in storage after the initial storage period an annual fee will be payable. This will be charged each year on the agreed renewal date.