Cryopreservation is the freezing of cells and tissue. In our clinic we use world class, safe and modern techniques such as vitrification to freeze cells and tissues. Cryopreserved samples are kept in liquid nitrogen at minus 196 ° Celsius. In this state, all the frozen samples can be stored for an indefinite period of time and used at a convenient time for fertility treatment.
What can be frozen:
- unfertilized egg cells
- fertilized oocytes
- testicular tissue
- ovarian tissue
Unfertilized egg cells
The freezing of unfertilised eggs is mainly performed for:
- Patients in need of immediate medical treatment that is toxic to the ovaries such as chemotherapy. (Please continue reading under Fertility Preservation).
- Patients who wish to postpone their desire to have children later in life and maintain their fertility.
After thawing of unfertilised egg cells, fertilization is only possible with the help of ICSI method.
Fertilized egg cells
During classic IVF treatment the number of eggs that are retrieved and fertilized is usually higher than the amount of embryos that can be transferred into the uterus at once. Therefore, all fertilized oocytes that won’t be used for transfer during the fresh cycle can be frozen and used later in a cryo cycle treatment. Main advantage of the cryo cycle is that the woman does not need to go through another hormone injection treatment, egg retrieval and anaesthesia. In addition to that there is significant less costs for cryo cycles in comparison to the stimulated cycle.
In some cases, if the risk of overstimulation after egg retrival is very high, all of the retrieved and fertilized eggs can be frozen. This will allow the patient to recover from the side effects of the hormone therapy and then have the fertilized eggs transferred to the uterus after recovery in a cryo cycle.
In Germany embryos may be frozen on exceptional circumstances. This is determined by the German Embryo Protection Act.
Cryopreservation of sperm is performed:
- if the male partner can not be present at the day of egg retrival during planned fertility therapy for any reason, e.g. due to business travel.
- if the man has any physical or psychological difficulties such as stress to provide sperm “on demand” for a fertility treatment (psychological potency disorder)
- before scheduled cytotoxic theraphies such as chemotherapy
Testicular tissue which is obtained through TESE is typically cryopreserved. Subsequently the preparation of the woman for fertility treatment (hormone stimulation and egg retrieval) takes place. However, please bare in mind that only ICSI can be used to fertilize the eggs using testicular tissue.
On the day of egg retrieval, part of the tissue is thawed, sperms are isolated and used for fertilization by ICSI.
Testicular tissue is cryopreserved:
- If ejaculated sperms have significantly impaired quality
- If no sperm is found in the ejaculate
- Before scheduled chemotherapy
Cryopreservation of ovarian tissue is primarily performed in pre-adolescent children and adolescents, and in women of reproductive age who have been diagnosed with cancer and require chemotherapy that damage their ovaries. Depending on the case, a portion of an ovary or even both ovaries are removed and sent to the IVF clinic for cryopreservation.
After the completion of the cancer treatment, when the time comes and the desire to conceive rises, ovarian tissue can be used again (transplantation of own tissue). Some time after the insertion of the ovarian tissue, the menstrual cycle begins again and the woman can become pregnant either naturally or with the help of IVF/ ICSI.