When sperm production is at fault and there is no much improvement with medicines, it means that there is a possibility of sperms becoming very less. This situation can happen in patients with severe low counts, varicocele and sometimes premarital. Preservation is done in liquid nitrogen at -160 degree C and it can stay good for at least 3-5 years. In case sperms do not improve or there is long time to plan for children, cryopreservation is handy. One should know that only 50% sperms retrieved from cryopreserved samples stay good. This means that patients with low counts to start with may have poor yield. However since the number of sperms needed in IVF or ICSI is very less (<20-30), it is usually possible to retrieve healthy sperms from cryopreserved samples. In patients undergoing cancer treatment in the form of radiation or chemotherapy it is wise to store sperms as they can be damaged.
This can be done for eggs and embryos as well.