Cryopreservation of Oocytes
In extracorporeal treatment cycles (IVF or ICSI), it cannot be excluded for sure that the number of fertilised oocytes is higher than the number of embryos to be transferred (maximum three embryos; common practice two embryos).
In order to save ‘supernumerary’ oocytes in a pronuclear state, cryopreservation (deep freezing preservation) is used. These fertilised oocytes can be thawed in later cycles and be transferred to the uterus at the embryonic stage of development. The procedure is well-established and safe, and increases pregnancy rates per oocyte extraction.
Cryopreservation of Sperm Cells or Testicular Tissue
The cryopreservation of human sperm cells and testicular tissue is an established method of fertility preservation in male patients confronted with malignant diseases (testicular cancer or leukaemia), prior to the commencement of ‘aggressive’ therapy (surgery, radiation or chemotherapy), which may lead to loss of fertility.
With the same goal intended, sperm cells can be cryopreserved before planned male sterilisation, or to provide sperm samples for sperm banks, to be used for heterologous insemination. Furthermore, cryopreservation is designated for patients undergoing microsurgical procedures (MESA or TESE), within the framework of assisted fertilisation.