Azoospermia in males, i.e. where there is no sperm present in the semen, can be because of two reasons. It can either be of the obstructive type where there is production of sperms in the testis but blockage of the conduction system, which brings the sperm out into the semen. Alternately, the azoospermia may be of the non-obstructive type, where there is a failure of the testes to produce sperms. In both these cases sperms can be extracted either from the Epididymis, in a procedure known as percutaneous epididymal sperm aspiration (PESA), or Testicle, in a procedure known as testicular sperm aspiration (TESA).
Sometimes when these don’t yield sperms then a biopsy of testicular tissue is taken, which sometimes has sperm attached. This is called testicular sperm extraction (TESE) or micro-TESE, if the surgery is carried out with a microscope and subsequently fertilized with egg using ICSI.