In a typical IVF or ICSI treatment cycle, the woman's ovaries are stimulated to produce many eggs. Following fertilisation and embryo culture, the best embryos are selected for embryo transfer. For about 50% of couples, there will also be good embryos which are surplus to those required for embryo transfer. These embryos can be frozen at this point for future use.
Embryo freezing (cryopreservation) is a method of preserving the viability of embryos be carefully cooling them to very low temperatures (-196oC). This is carried out in the laboratory using specialised freezing equipment and the embryos can then be safely stored in liquid nitrogen for extended periods.
PESA - In PESA, a butterfly needle is inserted into the epididymis to aspirate sperm under local anesthesia. Vasectomy patients are the strongest candidates for PESA.
MESA - MESA involves sperm aspiration through a small gage needle inserted into the epidydmis via the scrotum under local anesthesia. Urologists examine any fluid obtained through MESA to extract live, moving sperm. Men with little or no sperm in their ejaculate are candidates for MESA.
TESA - TESA is an open surgery under general anesthesia which requires a urologist to remove testicular tissue believed to contain pockets of sperm. Men with little or no sperm in their ejaculate are candidates for TESA. Because TESA is a more invasive procedure, there is a longer recovery time and greater expense.