Hydrocele vs Varicocele: Key Differences Explained

Finding a swelling in your scrotum can be worrying. Two of the most common harmless causes are a hydrocele and a varicocele. Comparing hydrocele vs varicocele comes down to one simple difference: a hydrocele is fluid, while a varicocele is widened veins. This guide explains how they differ in cause, feel and testing, when each needs treatment, and which warning signs mean you should get help quickly.

Hydrocele vs varicocele at a glance

	Hydrocele	Varicocele
What it is	Fluid around the testicle	Widened veins above the testicle
Cause	Fluid not draining, or a channel that did not close after birth	Faulty valves let blood pool in the veins
Where	Around the testicle, which may be hard to feel	In the cord above and behind the testicle
Feel	Smooth, tense, like a water balloon	Soft and lumpy, like a “bag of worms”
Lying down	Usually stays the same size	Usually shrinks or disappears
Side	Either side, or both	Mostly the left
Light test	Usually glows	Does not glow
Fertility	Rarely affected	Sometimes linked with poorer sperm

What is a hydrocele?

A hydrocele is a collection of fluid in the thin sac that surrounds the testicle. It makes one side of the scrotum swell, sometimes to a large size.

In babies, a hydrocele is common. It forms because the channel the testicle passed through before birth has not fully closed, so fluid from the tummy can collect around the testicle. Most go away on their own in the first year or two of life.
In adults, a hydrocele is more common with age. Often there is no clear cause, and the fluid simply builds up faster than it drains. Sometimes it follows an injury, an infection of the testicle or epididymis, or surgery in the groin, including varicocele surgery. Rarely, it forms around a testicular tumour.

A hydrocele is usually painless, but a large one can feel heavy or get in the way.

What is a varicocele?

A varicocele is a cluster of widened veins in the cord that holds up the testicle. Small valves in the testicular vein fail, so blood falls back and pools instead of draining up towards the heart. It is a bit like a varicose vein in the leg. Varicoceles usually appear around puberty and are found in about 15 in 100 men, mostly on the left.

Many cause no trouble. Some cause a dull ache that builds after standing, and some are linked with fertility problems. Learn more in our varicocele overview and our guide to varicocele symptoms.

How doctors tell them apart

How the swelling feels

A doctor will usually examine you lying down and then standing.

A hydrocele feels smooth and fluid-filled. It surrounds the testicle, so the testicle itself can be hard to feel. It does not usually change much when you lie down.
A varicocele feels like soft, twisted cords above the testicle. The testicle can be felt separately below it. It gets bigger when you stand or bear down and smaller when you lie flat.

The light test (transillumination)

A doctor may shine a small light through the scrotum in a darkened room. Clear fluid lets light through, so a hydrocele usually glows. Blood in widened veins does not, so a varicocele stays dark. This is a useful clue, but not proof. Blood, thick fluid or a hernia can give a misleading result, so it is not a reliable home test.

Ultrasound scan

A scrotal ultrasound is quick, painless and uses no radiation. It is the most reliable way to tell the two apart:

A hydrocele shows as a dark pocket of fluid around the testicle.
A varicocele shows as widened veins, usually 3 mm or more across, with blood flowing the wrong way when you strain. European radiology guidance recommends scanning standing up and during straining, because veins can look normal when you lie down.

Just as important, the scan checks the testicle itself. In an adult with a new hydrocele, the fluid can hide the testicle from the examining hand, so a scan is often advised to make sure nothing else is going on. Our guide to varicocele grades explains what a varicocele scan report means.

Varicocele and hydrocele together

You can have both. They are common enough to occur together by chance. A hydrocele can also develop after varicocele surgery when lymph fluid cannot drain as before. This happens less often with microsurgery and is uncommon after embolisation.

Varicocele and epididymal cyst

An epididymal cyst is another common, harmless lump. It is a small, smooth, fluid-filled swelling in the coiled tube (epididymis) that sits above and behind the testicle. It feels like a separate pea or marble and may glow with a light, like a hydrocele. A varicocele, by contrast, is softer, worm-like and changes size with position. An ultrasound easily tells them apart.

When does each need treatment?

Hydrocele

Babies and young children. Most are simply watched, because they usually go away. Surgery is considered if one is still there after about the age of one to two, or sooner if it comes and goes in size, which suggests a hernia.
Adults. A small, painless hydrocele can be left alone. Treatment is considered if it is large, uncomfortable or growing. The usual treatment is a small operation to remove or fold the sac (hydrocelectomy). Draining the fluid with a needle is possible, but the fluid tends to come back.

Varicocele

Most varicoceles need no treatment either. Doctors usually consider it for:

An ache that keeps returning and affects daily life
Fertility problems with an abnormal semen test (see varicocele and fertility)
A teenager whose testicle on that side is not growing properly

The options are surgery or embolisation. Compare them in our guide to varicocele treatment.

What else could a scrotal lump be?

Other causes include an inguinal hernia, infection or inflammation (epididymitis or orchitis), a twisted testicle (torsion) and testicular cancer. Testicular cancer is uncommon, but it is one of the most common cancers in young men. It usually shows as a painless, hard lump in the testicle itself.

When to see a doctor

Always get a new lump or swelling in the scrotum checked by a doctor, even if you think it is a hydrocele or a varicocele. See a doctor soon if a testicle feels hard or has a firm lump, if a swelling is growing, or if a baby’s swelling changes size during the day.

Sudden, severe pain in a testicle is an emergency. It may be testicular torsion, where the testicle twists and loses its blood supply, and it needs surgery within hours. Get urgent help too for testicle pain with vomiting or tummy pain, a hot, red, swollen scrotum with fever, or a painful groin bulge that will not go back in. In Singapore, call 995 in an emergency.

Frequently asked questions

What is the main difference between a hydrocele and a varicocele?

A hydrocele is fluid collecting in the thin sac around the testicle. A varicocele is widened veins in the cord above the testicle, caused by faulty valves. A hydrocele feels smooth and tense, while a varicocele feels soft and lumpy and gets smaller when you lie down.

Can you have a varicocele and a hydrocele at the same time?

Yes. They are common and can occur together, sometimes on the same side. A hydrocele can also develop after varicocele surgery, although this is less common with microsurgery. An ultrasound scan shows both clearly.

How is an epididymal cyst different from a varicocele?

An epididymal cyst is a small, smooth, fluid-filled lump in the coiled tube above and behind the testicle. It feels like a separate pea or marble. A varicocele is a softer, worm-like cluster of veins that changes size when you stand or lie down. Both are usually harmless, but a doctor should check any new lump.

Which is more serious, a hydrocele or a varicocele?

Neither is usually serious. A varicocele is more often linked with fertility problems. In adults, a new hydrocele can sometimes form because of infection, injury or, rarely, a testicular tumour, which is why a doctor will usually arrange an ultrasound to check the testicle itself.

Can I use a torch at home to tell them apart?

It is not a reliable home test. A doctor may use a light as one clue, but blood, thick fluid or a hernia can confuse the result. An examination and an ultrasound scan are needed to be sure.

Sources and further reading

This article is general information, not personal medical advice. Please speak to a doctor about your own symptoms. How we create our content.