Azoospermia, which is the absence of motile (and hence viable) sperm in the semen, occurs in %1 of all men, and %10-15 of all men which suffer from infertility related problems. Oligospermia is defined as the general absence of sperm in the semen.
In the cases of azoospermia, a small number of sperms can be found by centrifuging the semen. Those sperms could be enough for the micro-injection process, which would make surgery unnecessary.
In cases where no viable sperm is found in the semen, testicular sperm aspiration (TESA) or testicular sperm extraction (TESE) should be applied on the patient.
Azoospermia can occur due to various abnormalities:
⊕ The ejaculatory ducts could be obstructed; there is sperm production but the sperm cannot get out. In such cases, viable sperm could almost always be found by TESE.
⊕ There are also cases where, due to reasons unrelated to any obstruction, the sperm production is either very limited or non-existent. In such cases, it is possible to find and retrieve sperm by both TESA and TESE.