Cryopreservation is the deep-freezing of sperm, testicular or ovarian tissue, eggs cells or embryos and the storage in liquid nitrogen at -190 °C. Using this method, the longevity of tissue, sperm, eggs cells and embryos can be extended by several years.
In order for human cells and tissues to survive such low temperatures, the use of certain cryoprotective solutions and freezing procedures is required. This allows embryos, eggs and sperm to be preserved for later use without compromising their viability and function. In this way, treatments such as IVF, ICSI and insemination remain possible at a later date.
According to current legislation in Austria, the following materials can be cryopreserved in our TFP fertility clinics:
Embryos (cryopreservation of blastocysts) if more embryos have developed during IVF treatment than can be transferred, for example in the case of overstimulation, if the endometrium is too low or for other urgent medical reasons
Testicular tissue obtained during TESE
Sperm cells (cryopreservation of sperm)
Unfertilised eggs or oocytes in cancer patients who are at risk of infertility due to tumour treatment or chemotherapy.
"Social freezing", i.e. the deliberate freezing of eggs at a young age for later use, is not permitted in Austria.
In cancer patients who have to undergo radiation or chemotherapy, fertility can be significantly reduced or even completely lost. Of course, at the moment of diagnosis, one does not primarily think of the desire to have children, but it is very important and above all not costly to provide a sperm sample for safety before the start of a therapy. This can then be preserved for many years.
Depending on the quality and quantity of the ejaculate, up to three samples are required to preserve the semen to ensure fertility, each at an interval of four to five days. A waiting period of two to three days must be observed before each delivery.
Sperm cryopreservation is also offered at our TFP fertility clinics if your partner is unable to be present on the day of egg collection. This allows him to give his sperm in advance, which will be frozen until the day of treatment (ICSI). During follicular puncture, the frozen sperm is then used for fertilisation without any significant loss of quality.
In principle, however, the cryopreservation of sperm is not suitable for every sperm sample, as the mobility of the sperm is reduced after thawing. The experts at our fertility clinics will be happy to advise you on whether sperm storage is an option for you.
Cryopreservation of egg cells is only used for certain circumstances, such as prior to cancer treatment or in severe cases of endometriosis where premature depletion of the ovarian reserves is to be expected. The possibility of egg cell freezing gives women at an older age or in cases of premature ovarian failure a greater chance of having their own genetic children. We will be happy to advise you.
Sperm have been successfully cryopreserved for over 50 years, but eggs are very sensitive to ice crystal formation during freezing, which is why these methods should only be used in clinics with the appropriate expertise. TFP fertility clinics are among the first institutes in Austria to have successfully practised this technique.
Vitrification (a special freezing technique) can be used to store surplus embryos created during fertility treatment for future transfers. Cryopreserved embryos can then be thawed at a later date and transferred into the uterine cavity.
This allows a pregnancy to occur without having to go through all the therapy and hormone treatment steps of IVF or ICSI therapy again. This process is called a cryo-cycle. Due to improvements in freezing technology in recent years, the results with frozen and fresh embryos are now almost identical.
Embryo cryopreservation is also offered:
if there is a risk of hyperstimulation syndrome (OHSS)
in the case of certain stimulation protocols
if the endometrium is not optimal on the day of puncture
in the case of genetic testing (until the result is received)
for personal reasons that require a transfer at a later date
Cryopreservation is carried out in our fertility clinics at the Morula- or Blastocyst-stage. Here, special media enable very rapid cooling in liquid nitrogen, which prevents damaging ice crystal formation.
When are cryopreservation and cryotransfer used?
1. In the context of artificial or assisted fertilisation
It is often useful to freeze fertilised eggs in the pronucleus stage and have them stored for later intracytoplasmic sperm injection (ICSI) or in vitro fertilisation (IVF).
If necessary, these eggs can be further cultivated and used in the fertility clinic, for example if the couple would like to have another child later. This procedure is also called cryotransfer. The advantage of cryopreservation in this case is that the woman does not have to undergo hormone treatment and follicle puncture again.
2. Before treatment of serious diseases
With some serious illnesses, the risk of becoming infertile due to the necessary treatment - such as chemotherapy or radiotherapy for cancer - is very high. If you want to have children, you can take precautions and have sperm or testicular tissue, eggs or ovarian tissue frozen before the (cancer) treatment, after a detailed medical consultation and assessment of the risk of fertility loss.
A frozen fertilised egg can be further cultured and transferred to the uterus. This is called a cryotransfer. Unfertilised eggs that have been frozen are first fertilised via intracytoplasmic sperm injection (ICSI).
If the cycle conditions are optimal, the cryotransfer can be carried out without supportive hormone therapy. However, it is also possible to support the build-up of the uterine lining with oestrogens and optimally prepare it for implantation of the egg. Your doctor at the fertility clinic will then measure the thickness of the uterine lining.
If it is thick enough, ovulation is simulated by administering the corpus luteum hormone progesterone. This changes the structure of the mucous membrane and makes it ready to receive embryos. A third variant is hormonal stimulation with clomiphene or FSH to support follicle maturation before embryo transfer. Then the embryos can be transferred into the uterus with a soft catheter.
The health insurance companies and also the IVF fund in Austria do not usually cover the costs of cryopreservation - even if it is carried out because of the treatment of a serious illness. Find out more about the costs for private patients in our fertility clinics.
Cryopreservation has been used for many years and most studies show no adverse effects. However, individual counselling is always part of the treatment.