Not all cases of male infertility or azoospermia (absence of sperm in the ejaculate) are the same and should be treated in the same way. Azoospermia is divided into two large groups – obstructive azoospermia and non-obstructive azoospermia. Obstructive azoospermia is present when there is normal sperm production in the testicles, but the seminal ducts are blocked. Cause of occurrence and can be: Vasectomy – this is one of the most common causes of obstructive azoospermia. The reason is that this surgical intervention cuts off the seminal ducts, which also cuts off the flow of sperm. Infection: Obstructive azoospermia can also be caused by infections of the testicles, prostate or reproductive tract such as epididymitis / orchitis, prostatitis and sexually transmitted diseases such as chlamydia. They can cause blockage of the small tubules of the epididymis or the ejaculatory duct. NEWS_MORE_BOX Congenital anomalies: Some men are born with part of the vas deferens missing. In practice, this is a condition similar to a vasectomy, but the cause is genetic. Another congenital abnormality that can lead to obstructive azoospermia is cysts of the prostate gland. Another reason for the occurrence of obstructive azoospermia may be postoperative complications. Non-obstructive azoospermia is a condition in which there is a problem in the process of sperm formation. They are either absent or the level of their production is very low. Reasons for the development of non-obstructive azoospermia can be genetic, acquired and congenital. Among the genetic causes, the most common is a chromosomal abnormality. The most common chromosomal problem causing azoospermia is Klinefelter syndrome. Varicocele is also one of the diseases that in most cases lead to a slight decrease in the number of sperm, but in some cases it also leads to azoospermia. Testicular cancer: One of the first and most common symptoms of testicular cancer or other organs of the reproductive system is azoospermia or low sperm count.