TESE 

The absence of sperms in the semen test is called azoospermia, which can be caused by the absence of sperm in the testicle or by the blockage of the sperm transmission duct. Each of these cases can be caused by genetic causes, infections, and medical injuries. Clinical examinations, blood tests for hormonal studies and genetic studies are all helpful in the diagnosis of azoospermia. Of course, none of these methods alone or together can predict the presence or absence of sperm certainly.

The only definitive method for assessing the presence or absence of sperm in testicles is through a surgical biopsy of the testis (TESE; testicular sperm extraction); or TESA (testicular sperm aspiration) and PESA (percutaneous epididymal sperm aspiration) which is performed by sticking a needle in the testis (or epididymis) and aspirating fluid and tissue with negative pressure.

Indeed, in recent years, with the advent of a microinjection and ICSI techniques that can be carried out with a few number of sperms, these methods can be a solution for men with azoospermia.