What Causes Obstructive Azoospermia?

Obstructions occur most commonly in the:

• Epididymis: The coiled tube on the back of each testicle where sperm matures
• Vas deferens: The tube that transports sperm from the epididymis
• Ejaculatory duct: The tube from which the sperm exit into the urethra and mix with fluid to form semen

Epididymis blockages

Several conditions can lead to a blockage in the epididymis:

• Infections (such as epididymitis)
• Inflammation
• Scrotal trauma/injury
• Rare genetic conditions: They can cause either a blockage or abnormal development. Cystic fibrosis can cause thickened secretions, leading to a buildup and semen getting stuck. This is sometimes even a problem for men with a cystic fibrosis gene mutation but no other disease symptoms.

Depending upon the cause, many cases are correctable with microsurgery.

Surgery on the vas deferens

During a vasectomy, your surgeon cuts or clamps each vas deferens, stopping the flow of sperm. But there are other conditions that can have the same impact:

• Trauma/injury
• Previous surgery for other reasons, including hernia repair
• Cystic fibrosis gene mutations, which can cause the normal connection to the urethra not to form

Microsurgical repair can often fix the obstruction or repair the connection.  

Ejaculatory duct blockages

Some ejaculatory duct blockages are present at birth (congenital). Others develop later on (acquired), from:

• Infections
• Trauma
• Prior surgery

Endoscopic surgery can relieve the blockage and often restore sperm to the semen.