Sperm freezing is the most successful method of preserving a man’s fertility so he can try and have children at a later date. It's also used to store sperm so it can be used in someone else's treatment.
What is sperm freezing?
Men are able to freeze their sperm for use in their own future treatment or to donate to someone else’s treatment. Donated sperm usually has to be stored for six months first in order to screen the donor for infections (unless the clinic uses a process called Nucleic Acid Testing [NAT], which is quicker but not recommended by professional bodies.)
Sperm freezing can be carried out for patients who are at risk of subfertility because of treatment which may have a long-term effect on sperm production or quality. The most common cases are patients who need chemotherapy or radiotherapy to treat cancer.