Hydrocele in Adults

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A hydrocele is a collection of fluid in the scrotum. Most develop for no apparent reason, are harmless, and can be left alone. If needed, a small operation can usually cure the problem. In a small number of cases, a hydrocele is due to an underlying problem with a testicle (testis).

The scrotum is normally loose, soft and fleshy. It holds the two testicles (testes). Usually you can easily feel the testes in the scrotum. A tube (the vas deferens) takes sperm from each testicle (testis) to the the penis. It is normal for one testis to hang lower than the other.

A hydrocele is a collection of fluid in a sac in the scrotum next to a testicle (testis). It usually occurs on one side, but sometimes a hydrocele forms over both testicles (testes).


The normal testis is surrounded by a smooth protective tissue sac. You cannot normally feel this. It makes a small amount of 'lubricating' fluid to allow the testis to move freely. Excess fluid normally drains away into the veins in the scrotum. If the balance is altered between the amount of fluid that is made, and the amount that is drained, some fluid accumulates as a hydrocele.

See also the separate leaflet called Get to Know Your Testes (Testicles).

A hydrocele feels like a small fluid-filled balloon inside the scrotum. It feels smooth, and is mainly in front of one of the testicles (testes).

Hydroceles vary greatly in size. Very large hydroceles are sometimes seen in elderly men who have never shown their swelling to a doctor. It might have been getting larger over a number of years.

Hydroceles are normally painless. Large hydroceles may cause discomfort because of their size. Walking or sexual activity may become uncomfortable if you have a very large hydrocele.

Most hydroceles occur in adults and are most common in men aged over 40 years.

  • The cause is not known in most cases.
  • A small number of hydroceles are caused when something is wrong with one of the testicles (testes). For example, infection, inflammation, injury or tumours of a testicle (testis) may cause fluid to be formed which leads to a hydrocele forming.
  • Sometimes hydroceles develop when there is generalised swelling of the lower half of the body due to fluid retention.

A doctor will examine the testicles (testes). Your doctor may also shine a light through the scrotum, which helps to diagnose a hydrocele.

If the hydrocele is large, and the doctor cannot feel the testicle (testis), the fluid may be drained with a needle and syringe. (This is helped by injecting local anaesthetic into the overlying skin to make the procedure painless.) Once the fluid is removed, the testes can then be examined more easily.

Sometimes an ultrasound scan of the testes will be advised. This can check the testes to make sure there is no underlying cause for the hydrocele.

Leaving it alone can be an option

In adults, if the hydrocele causes no symptoms, one option is simply to leave it alone. If it becomes larger or troublesome, you can always change your mind and have treatment.


Surgery may be recommended if your hydrocele is large or uncomfortable. The operation for a hydrocele involves making a very small cut in the scrotum or lower tummy (abdominal) wall. The fluid is then drained from around the testicle (testis). The passage between the abdomen and the scrotum will also be sealed off so the fluid cannot re-form in the future. This is a minor operation and is performed as a day case, so does not usually involve an overnight stay in the hospital. A hydrocele may return after surgery but this is very uncommon.


The fluid can be drained easily with a needle and syringe. However, following this procedure, it is common for the sac of the hydrocele to refill with fluid within a few months. Draining every now and then may be suitable though, if you are not fit for surgery or if you do not want an operation.

Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
4389 (v39)
Last Checked:
Next Review:
The Information Standard - certified member
See also: Hydrocele written for professionals
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