In reproductive medicine, cryopreservation (Greek κρύος, krýos “cold” and Latin conservare “to preserve, keep”) is the preservation of sperm (sperm cells), testicular tissue, ovarian tissue, oocytes, and fertilized oocytes in the pronuclear stage by freezing them in liquid nitrogen. With the help of this procedure it is possible to maintain the vitality of the cells almost indefinitely:
Cryopreservation is offered:
- As a fertility-preserving measure of oncological patients/tumor patients (here: sperm, testicular tissue, ovarian tissue and oocytes).
- To make the implantation (implantation) of the embryo more “physiological”; however, this has not improved the chances of success of in vitro fertilization (IVF; artificial insemination in a test tube).
Further notes
- Children born after in vitro fertilization (IVF) in which the fertilized egg was previously frozen had a higher likelihood of cancer (44.4 per 100,000 person-years versus 17.5 per 100,000 person-years; hazard ratio was 2.43, which was statistically significant with a 95% confidence interval of 1.44 to 4.11); the increased risk was mainly due to leukemias, neuroblastomas, or other tumors of the sympathetic nervous system.
- On July 6, 2019, the first birth of a child after fertility-preserving measures took place in a woman who had breast cancer. This was a pregnancy from thawed eggs fertilized by intracytoplasmic sperm injection (ICSI* ) and transferred to the uterus (womb) as a germinal stage embryo. This was followed by the harvesting of 17 antral follicles by transvaginal ultrasound (ultrasound procedure in which the ultrasound probe is inserted through the vagina) and subsequent in vitro maturation, i.e. the transfer of follicle maturation in vitro (oocyte maturation in the test tube). The oocytes (eggs) thus matured were then snap-frozen in liquid nitrogen (vitrification).
- Embryo cryopreservation and duration of storage: longer storage time was associated with poorer pregnancy success and lower live birth rates: when stored for 12 to 24 months, the implantation rate (number of children born alive divided by the number of embryos transferred) decreased from 40% to 26%, the clinical pregnancy rate from 56% to 26%, and the live birth rate from 47% to 26%, compared with storage for 3 months.
- Ovarian Tissue Cryopreservation (OTC): with OTC, 39% of women became pregnant at least once and 18% delivered a healthy baby. However, in advanced childbearing age, women have poor chances of becoming pregnant through the transplantation of cryopreserved ovarian tissue and subsequent IVF: the age limit was 35 years.
* In this procedure, a single sperm (sperm cell) is injected directly into the cytoplasm (ooplasm) of an egg using a microcapillary. The procedure is always combined with in vitro fertilization (IVF; “fertilization in a jar”).
Note: Cryopreservation of eggs and sperm as well as the associated medical measures are paid for by the statutory health insurance under certain conditions. Those under 18 years of age and, in general, women over 40 and men over 50 are excluded.
Please note
The physical and mental health of men and women as well as a healthy lifestyle are important prerequisites for successful fertility treatment.
Before starting therapeutic measures, you should in any case – as far as possible – reduce your individual risk factors!
Therefore, before starting any reproductive medical measure (e.g. IUI, IVF, etc.), have a health check and a nutritional analysis performed to optimize your personal fertility (fertility).
