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Kyro preservation (vitrification)

The Kinderwunschzentrum Niederrhein also offers cryopreservation ("cold preservation") of sperm, testicular tissue, eggs and embryos. This procedure is not only used within the framework of fertility treatments, but is also advisable, for example, for medically necessary tumour therapies.

The long-term storage takes place in the cryobank of the company Kryo-Kindwunsch GmbH & Co.KG. Here, for example, the stored genetic material can be kept for many years and can be retrieved if required for insemination, IVF or ICSI.

If you are interested in cryopreservation, please contact us!

If you have any questions or uncertainties, please contact our IVF laboratory team!


The freezing (cryopreservation) of sperm is particularly advisable if a pending treatment (e.g. chemotherapy for testicular tumours) is accompanied by a prolonged quantitative and qualitative impairment of sperm cell formation.

We carry out the cryopreservation of sperm for long-term storage in the cryobank of Kryo-Kindwunsch GmbH & Co.KG. Here the stored genetic material can be kept for many years and, if necessary, can be retrieved for insemination, IVF or ICSI. Within the framework of infertility treatment, other reasons such as mental impotence, illness or a longer absence of the partner may also make the cryopreservation of sperm necessary. The frozen sperm samples are stored in our practice for this purpose and can be thawed if necessary and used for the corresponding treatment procedures. Cryopreservation is of course also possible with sperm cells obtained by MESA (microsurgical epididymal sperm aspiration). Likewise, testicular tissue obtained by TESE (testicular sperm extraction) can also be kept deep-frozen. As a rule, several samples can be frozen at a time, which allows several ICSI cycles to be performed. Therefore, usually only a single surgical procedure is necessary. Testicular tissue samples can also be stored in the cryobank of Kryo-Kindwunsch GmbH & Co.KG for many years.

Cryopreservation of early egg cell stages up to the mature egg cell (in an unfertilised state) was only possible with unsatisfactory success until recently, as suitable freezing methods were not available. Thus, it was not possible to safeguard the fertility of women who had to undergo chemo- or radiotherapy and/or removal of the ovaries due to cancer. The development and refinement of new freezing techniques (e.g. vitrification), however, has recently led to the fact that high survival and satisfactory fertilisation rates can now be achieved after cryopreservation even with so-called metaphase II eggs (mature unfertilised eggs).After hormonal stimulation of the ovaries by means of transvaginal follicle puncture, it is possible to obtain oocytes, freeze them and store them deep-frozen for many years while maintaining their biological activity.

If a couple wishes to have children, these eggs can be thawed and fertilised extracorporeally. The resulting embryos are then transferred to the woman's uterus (embryo transfer). Depending on the protocol, the stimulation of the ovaries requires about 14 days and in some cases delays the rapid start of oncological treatment. An alternative is in vitro maturation (IVM), which is based on the retrieval of very early egg cell stages (from the 5th to the 7th day of the cycle) from ovaries that have only been stimulated for a short time. These obtained early stages are first frozen, and if necessary, later induced to mature further in the laboratory and fertilised if necessary. The cryopreservation of ovarian tissue is also promising and in individual cases has already led to the formation of follicles, ovulation and the birth of a child after autotransplantation of the thawed tissue. Both in vitro maturation and ovarian tissue banking are methods that need to be further developed and may be available as standard procedures in the future.

Often, IVF or ICSI treatment results in multiple fertilized eggs. According to the German Embryo Protection Act, however, only three fertilised ova (pronuclear ova) may develop into an embryo. However, it is possible to freeze the surplus pronuclear oocytes (cryopreservation). The frozen pronucleated egg cells can be thawed in later cycles, grow into embryos and finally be transferred to the uterus. However, the chance of pregnancy is reduced compared to the transfer of "fresh" embryos. To maintain the fertility of tumour patients, the cryopreservation of germ cells is recommended. The treatment of tumour patients with chemo- or radiotherapy can cause temporary or even permanent infertility. For the affected patients, the desire for a child at a later stage can often only be fulfilled if eggs or ovarian tissue are cryopreserved in good time before the tumour treatment. The cryopreserved samples can be stored for many years without loss of biological activity and can be used for fertility therapy if required. For women, cryopreservation of surplus fertilised eggs (pronucleus stages) resulting from artificial fertilisation treatment has been standard practice for many years. Thanks to improved freezing protocols, it is now possible to freeze mature eggs (metaphase II stages) and thaw them at a later stage in order to fertilise them for transfer to the patient's uterus and thus fulfil her wish to have a child. In the meantime, the pregnancy rates that can be achieved in this way are well within the range of those achieved with freshly retrieved eggs. The cryopreservation of ovarian tissue is also becoming increasingly important. Future findings must provide information on the optimal use of deep-frozen germ cell tissue.

Intensive research is currently underway:

  • Autotransplantation, in which the patient's own thawed tissue is transplanted either in the abdominal cavity (orthotopic) or at a specific location under the skin (heterotopic). The aim here is either to restart hormone production, to restore the ability to conceive spontaneously if the patient wishes to have a child, or to allow follicles to mature for egg production.
  • Xenotransplantation, in which the thawed tissue is implanted into immunodeficient mice with the aim of allowing follicles to mature there to obtain oocytes.
  • In vitro maturation, in which the thawed tissue is cultivated in the laboratory to obtain oocytes.

All three procedures make it possible to obtain mature oocytes that can be fertilised by established standard in vitro fertilisation procedures. The resulting embryos can be transferred to the patient's uterus and eventually lead to the desired pregnancy. It remains to be seen which of the described procedures will ultimately prevail. Recent research results, however, give reason to hope that satisfactory treatment results can be achieved in the not too distant future. In view of the fact that chemo- or radiotherapy can seriously endanger a woman's fertility, cryopreservation of ovarian tissue should already be recommended to an affected patient today, since, as shown, it is to be expected that promising treatment methods will soon be established and the option of maintaining fertility by cryopreservation is only available once.

For some time we have been working together with the company Kryo-Kindwunsch GmbH & Co KG in the field of cold preservation of sperm and testicular biopsies. Such a measure is necessary for patients who are at risk of temporary or even permanent infertility due to a medically necessary tumour therapy (e.g. chemo- or radiotherapy). For those affected, usually very young men, the desire for children at a later stage can often only be fulfilled if sperm is cryopreserved in time for tumour treatment, or in the case of azoospermic patients with sufficient sperm genesis, testicular biopsies are cryopreserved. The cold-preserved samples can be stored for many years and used for fertility therapy if required.

Patients who wish to have their genetic material cryopreserved should have a current spermiogram with the corresponding microbiological examination. If possible, patients should come to us at least two to three weeks before the upcoming tumour treatment. This will allow enough time to freeze the sperm of several ejaculates in order to have as large a reservoir as possible available for later fertility treatment. Of course we also offer this service to men who wish to undergo sterilisation.

Cryopreservation of testicular biopsies can also be arranged at short notice if the procedure is performed by yourself. Otherwise we cooperate with experienced colleagues for this purpose. Please contact us in good time to arrange an appointment. We will organise the transport of the sperm samples or testicular biopsies to Kryo-Kindwunsch GmbH & Co.KG.

Some health insurance companies cover the costs for the cold preservation of sperm or testicular tissue of tumour patients. All health insurers decide on a case-by-case basis whether to cover the costs. It is therefore advisable to submit an informal application to the health insurance company in advance of a planned tumour therapy to have the costs covered. Prices for cryopreservation on request.