Photo of a man (PantherMedia / reana)

Varicoceles are varicose veins in the scrotum (the sac that holds the testicles).

They form in the veins that run along the spermatic cord. Blood from the testicles flows back into the body through those veins. Like varicose veins in the legs, varicoceles form when blood builds up in the veins and they become permanently enlarged.


Varicoceles don't normally cause any symptoms. But they can sometimes lead to swelling, a feeling of tightness or a dull, “dragging” pain in the testicle.

Causes and risk factors

There are probably a number of reasons why veins in the scrotum sometimes become enlarged, including anatomical reasons: For instance, if the testicular vein joins the renal (kidney) vein at an almost right angle in the pelvis, the blood in the veins flows more slowly. This can cause the blood to build up in the scrotum, resulting in a varicocele. When the curve where the two veins meet is too tight, it's usually on the left side. That's why varicoceles are more common on the left side of the scrotum. Other possible causes of varicoceles include weak walls of the vein at birth and – like varicose veins elsewhere in the body – weak valves inside the vein.

In rare cases, varicoceles are caused by a tumor in the pelvis or abdomen. Tumors can push against veins and prevent the blood from flowing properly.


Varicoceles are common, particularly in teenage boys and men between the ages of 15 and 25. Experts believe that 5 to 15% of all men have a varicocele. About 90% of them have it on the left side of their scrotum.


It is thought that varicoceles can reduce fertility. Varicoceles are more common in men who have fertility problems. According to estimates, about 25 to 37% of all men who have poor sperm quality also have a varicocele. But varicoceles don’t always affect fertility: Many men with varicoceles don't have fertility problems.


Doctors can diagnose larger varicoceles just by looking at them or feeling them. They sometimes have to apply pressure to the belly so that the varicose vein fills with blood and can be felt.

Smaller varicoceles can only be found using ultrasound (sonography).


Varicoceles usually don't need to be treated. Men who have fertility problems are sometimes offered treatment to try to increase their chances of having children.

The treatment involves “shutting down” the affected vein so that the blood can flow through healthy, nearby veins instead. This can be done by blocking the vein using minimally-invasive procedures (embolization) or by performing varicose vein surgery.

The vein can be blocked with medication or special small metal coils that are released using a catheter inserted into the vein. The medication or coils cause a blood clot to form in the varicose vein, closing it off. The medical term for this is embolization. A different form of embolization – known as sclerotherapy – involves using a solution that damages the walls of the vein, causing them to scar and stick together. In surgery, the swollen vein and the surrounding smaller veins are either cut or tied off. This is either done through "open" surgery using a larger cut – for instance in the scrotum or in the groin – or through minimally invasive "keyhole" surgery. In keyhole surgery, the surgical instruments are inserted through small cuts.

The possible complications of treatment include bleeding, wound infections, injury to nerves or swelling in the scrotum (a hydrocele).

Research summaries

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.