The most common causes of no sperm production in men involve genetic defects which affect their fertility. Sometimes these defects may impact the production of sperm, and other times they may lead to a blockage which prevents sperm from being released. Other potential causes for little or no sperm count may include injury to the testicles or penis and vasectomy.
Klinefelter's syndrome is the most common cause of no sperm production. It is a genetic mutation in which a male has an extra sex chromosome. Most men have one X chromosome and one Y. Those with Klinefelter's Syndrome have an extra X chromosome, leading to excessive breast production, small hard testicles, and infertility. There are also genetic defects which may alter the hormonal balance in males, and these can also lead to a lack in sperm production. Men who are having problems fathering a child with their partners should be tested for these abnormalities.
Another genetic condition which may lead to no sperm is a congenital absence of the van deferens (CAVD). This results in a lack of ducts which are needed to secrete sperm into semen. Sometimes the male might have ducts but they are malformed. Males with this condition typically have average sperm production, but the sperm cells are trapped inside the testicles with no way to escape. Men with CAVD can still impregnate a woman through artificial insemination, or in some cases, surgery may be performed to remove any blockages.
In some instances, a man may have an absence of sperm for unknown reasons. Other times an injury to the penis or testicles may result in no sperm production. In these instances, some men may have corrective procedures to repair the damage. Many times this cannot be done, however, and permanent infertility results.
Men who have had a vasectomy will also have a sperm count of zero. Sperm are still produced in the testicles, but the passageway between them and the penis is blocked or severed. In some cases a vasectomy can be reversed and full or partial fertility may be restored, but this isn't always an option.
Even men who have a zero sperm count may have small numbers of sperm within the testicles. Modern infertility treatments can sometimes allow for the retrieval and use of these sperm cells. Those who truly have no sperm may have to resort to using a sperm donor in order to have a family with their partners.