Men with no sperms in their ejaculate may be suffering from absence or obstruction of the vas deferens due to infection, trauma or surgery. Sperms can be surgically retrieved from the epididymis of these men – a procedure known as microsurgical epididymal sperm aspiration (MESA). Some may have retarded spermatogenesis (i.e., testicular failure), in which case, there is a 50% chance of retrieving sperms from their testes by means of testicular sperm aspiration (TESA). The sperms thus obtained can be used immediately or cryopreserved for later use.
Some men recently diagnosed with cancer can have their sperms cryopreserved before they commence chemotherapy and/or radiotherapy.