A varicocele is a dilated (enlarged) group of veins in the scrotum, around the testicles.

Varicoceles are similar to varicose veins that occur in the legs.

Men with varicoceles may notice heavy, dragging or aching feeling in the scrotum.

Varicoceles are a common cause of low sperm counts and decreased quality of sperm, which may lead to infertility. However, not all varicoceles affect male fertility.

Varicoceles can also cause the testicles to fail to develop normally or shrink (atrophy).

Fortunately, most varicoceles are easily diagnosed and many do not require treatment.

If a varicocele causes symptoms or signs, then it should be treated, either by embolization or surgery.

The spermatic cord carries blood to (arterial) and from (venous drainage) the testicles.

Many experts believe that a varicocele occurs when the valves inside the testicular veins prevent your blood from properly flowing out of the scrotum.

This results in backup of the venous blood, causing the veins in the scrotum to widen (dilate), thus formation of the varicocele.

This reflux may then result in damage to the testicle and may worsen fertility. 

Varicoceles may be asymptomatic and only discovered incidentally.

When varicoceles are symptomatic, these can be variable:

• Pain:
• May vary from dull aching discomfort to sharp pain
• Increases with standing or physical exertion, especially over extended time periods
• Worsening of the course of the day
• Pain decreases or relieved by lying flat on your back
• "Bag of Worms": when palpating or feeling the scrotum it may feel like a "bag of worms", but usually not tender.

With time, varicoceles may increase in size and become more apparent.