A procedure in which a sample of sperm cells and tissue are removed from the testicle through a syringe attached to a small needle. The sperm is separated from the tissue and looked at under a microscope in the laboratory. It may then be used right away to fertilize eggs or frozen for future infertility treatment. Testicular sperm aspiration may be useful for men who have fertility problems caused by a blockage that keeps sperm from being ejaculated. This could be caused by previous vasectomy, certain genetic conditions, ejaculation problems, infection, or other conditions. It may also be useful for men who want to have children after having treatment that may cause infertility, such as certain cancer treatments. Testicular sperm aspiration is a type of sperm retrieval method. Also called TESA.