A procedure in which a sample of sperm cells is removed from the epididymis through a syringe attached to a small needle. The epididymis is a narrow, tightly-coiled tube that is attached to each of the testicles and is where sperm cells mature and are stored. The sperm is looked at under a microscope in a laboratory, where it may be used right away to fertilize eggs or frozen for future infertility treatment. Percutaneous epididymal 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, 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. Percutaneous epididymal sperm aspiration is a type of sperm retrieval method.