Cryopreservation

Freezing fertilised oocytes

If more oocytes are fertilised during IVF or IVF/ICSI treatment than embryos are transferred to the uterus, we can cryopreserve the surplus fertilised oocytes in the pronuclear stage. Then, if necessary, they can be thawed later and transferred to the uterine cavity as developed embryos. This means that pregnancy can occur without having to go through all the steps of IVF or IVF/ICSI treatment again. Experience shows that this proven procedure increases the pregnancy rate associated with oocyte retrieval.  

Freezing blastocysts

Surplus blastocysts from IVF or IVF/ICSI treatment are cryopreserved and used for further or later fertility treatment. This means that pregnancy can occur without having to go through all the steps of IVF or IVF/ICSI therapy again (known as cryotransfer). The pregnancy rate related to egg retrieval can be increased (cumulative pregnancy rate). 
 

Sperm or testicular tissue freezing

This is useful if the man is about to have a testicular operation or chemotherapy or radiotherapy that will affect his fertility - but he still wants to father children afterwards. In individual cases, the sperm can also be frozen before the man is absent for a longer period of time in order to use them for ICSI or insemination treatment in due course. The same applies to sperm or testicular tissue obtained during a TESE. 

Freezing of ovarian tissue

Cancer treatment at a young age can damage ovarian function and lead to menopausal symptoms and infertility. In order to make pregnancy possible afterwards, we can freeze ovarian tissue. This is taken from you during an abdominal endoscopy and cryopreserved in our laboratory after preparation. This process can be done within a few days. When the time comes for pregnancy, we thaw and retransplant the ovarian tissue.
This is a solution for young patients with very good ovarian functional reserve. After the age of 35, we recommend it only in individual cases. A combination with other fertility-preserving measures – such as the cryopreservation of oocytes (primary oocytes) – is also possible, provided that sufficient time is available. 

How cryopreservation works

In order to preserve the quality of the oocytes, we use "rapid freezing" (vitrification). In this process, the oocytes are dehydrated and cooled to 196 °C in a fraction of a second in liquid nitrogen. When the time comes for artificial insemination, we thaw them out just as quickly. As a result, on average about 90% of all cryopreserved oocytes survive. While freezing and thawing must be done extremely quickly, storage can theoretically be done indefinitely.