A hydrocele is a collection of fluid around the testicle. It is common, it is almost always harmless, and it is one of the more straightforward problems I see. What it is not is something to guess at from the outside — a swollen scrotum has several possible causes, and they are treated very differently.

This page covers what a hydrocele is, how to tell it apart from a varicocele, when it needs an operation and when it does not, and what the repair actually involves.

Hydrocele or varicocele? The short answer

These two get confused constantly, and it is easy to see why: both cause a swelling in the scrotum, and both are usually harmless. They are not the same thing.

Telling them apart

A hydrocele is fluid. It feels smooth and full, rather like a small water balloon around the testicle. The size stays much the same whether you are standing or lying down. It can occur on either side.

A varicocele is veins. It is often described as feeling like a bag of worms above and behind the testicle. It usually becomes more obvious when you stand up or strain, and it tends to soften or vanish when you lie flat. It sits on the left far more often than the right.

One more practical difference: a varicocele is sometimes relevant to fertility, and a hydrocele on its own is not.

Neither description is a substitute for being examined. The two can also coexist, and a scan settles it in minutes.

Think it might be a varicocele?

If the swelling feels like a bag of worms, is worse on standing, and eases when you lie down, read about varicoceles and what they mean for fertility.

What a hydrocele actually is

The testicle sits inside a thin, two-layered membrane called the tunica vaginalis. A small amount of fluid between those layers is normal — it lets the testicle move freely. A hydrocele is what happens when more fluid collects there than the body reabsorbs.

In adult men a hydrocele is usually described as primary, meaning no particular cause is found. It can also be secondary, developing after an injury, an infection such as epididymitis, or surgery in the groin or scrotum. Hydroceles become more common with age.

The swelling is typically painless. What most men notice first is the size, the weight, or the way it makes clothing and exercise awkward. Some describe a dull ache rather than pain.

Does it need treating?

Often, no. A hydrocele that is small and does not bother you needs nothing beyond an accurate diagnosis. Leaving it alone is a legitimate choice, not a failure to act.

Treatment is worth considering when the hydrocele is:

    • large enough to be uncomfortable, heavy or visible through clothing
    • getting in the way of exercise, sex or work
    • causing an ache that does not settle
    • worrying you enough that it affects daily life — worth saying out loud in clinic, though worry on its own is usually better answered by a scan and a clear explanation than by an operation

Draining it with a needle is not a solution. Aspiration removes the fluid, but it re-accumulates — usually quickly — and the needle can introduce infection. It is not curative and it is not standard practice. Surgery is the only treatment that reliably stops the fluid re-forming, though it is not a guarantee: hydroceles recur after surgery in between 1 in 50 and 1 in 250 men.

This is NHS work too

Hydrocele repair is a standard NHS operation, and your GP can refer you for it. Many areas apply access criteria, so the NHS will usually want the hydrocele to be causing real symptoms rather than simply being present — which is the same threshold I would apply myself.

What private care buys you is time and continuity: a shorter wait, and the same surgeon from the first scan to the follow-up. It does not buy you a different operation. If the NHS route suits you better, that is a perfectly good answer and I will say so.

Getting the diagnosis right first

I will examine you and, in almost every case, arrange a scrotal ultrasound. That is not because a hydrocele is dangerous. It is because fluid around the testicle makes the testicle itself impossible to feel properly, and I would rather look than assume.

To be clear about the level of risk: when Austrian urologists reviewed 156 men who had surgery for an apparently uncomplicated hydrocele (Kafka and colleagues, Anticancer Research, 2020), pre-operative ultrasound found no malignancies at all. The scan is a matter of good practice, not alarm. Occasional case reports do describe a tumour hidden behind a hydrocele, which is precisely why the scan is routine rather than optional.

When to be seen sooner rather than later

Please arrange assessment promptly, rather than waiting, if you notice a firm lump within the testicle itself, a swelling that appears suddenly or grows quickly, or scrotal swelling with fever or redness.

Sudden, severe testicular pain is different again. Pain that comes on abruptly and lasts more than an hour needs same-day emergency assessment — go to A&E. That is not a hydrocele.

The operation

Hydrocele repair is a short, well-established day-case procedure. It is normally done under a general or spinal anaesthetic; a local anaesthetic is possible but unusual.

    • A small incision is made in the scrotum and the fluid is drained.
    • The sac that held the fluid is then bunched up with absorbable stitches, or closed off behind the testicle, so the fluid cannot re-form.
    • If the sac wall is very thick, it is removed altogether.
    • The skin is closed with dissolvable stitches, and you are given a scrotal support to wear.

You may be given antibiotics at the time of surgery, and stockings or a blood-thinning injection to reduce the risk of clots.

One thing to expect: the treated side will always feel bulkier than the other. The bunched-up sac stays where it is. This is normal after the operation rather than a sign that something has gone wrong, and it is better to hear it now than afterwards.

Recovery

    • Swelling, bruising and discomfort in the scrotum are near-universal, and last from several days to a few weeks.
    • Wear the scrotal support. If it is uncomfortable, tight supportive underwear or cycling shorts do the same job.
    • Paracetamol or ibuprofen usually handles the discomfort. Ice packs help in the first few days — wrapped, never directly against the skin.
    • The stitches dissolve and normally disappear after two to three weeks.
    • Avoid heavy lifting and strenuous exercise for at least four weeks.
    • Most men do not need a routine follow-up appointment, though one can be arranged.

Bruising, swelling or pain that gets worse day by day is not part of normal recovery. Contact the surgical team if that happens.

The risks, with the actual numbers

These figures come from the British Association of Urological Surgeons patient information leaflet on adult hydrocele repair, which is the standard UK reference. Very rare effects, occurring in fewer than 1 in 250 patients, are not listed individually.

    • Swelling, discomfort and bruising of the scrotum, lasting several days to a few weeks.
    • A bulky feeling around the testicle, from the bunched-up hydrocele sac.

    • A blood collection (haematoma) around the testicle or wound, which either resolves slowly or needs surgical removal.
    • Infection in the incision or the testicle, needing antibiotics or surgical drainage.

    • Recurrence of the hydrocele.
    • Inadvertent injury to the epididymis, the vas deferens or the blood supply of the testicle.
    • Chronic pain in the testicle or scrotum.
    • Anaesthetic or cardiovascular problems, possibly requiring intensive care. Your anaesthetist can estimate your individual risk.

BAUS also notes that the risk of acquiring an infection in hospital is between 4 and 6 per cent, and that this is higher in patients with long hospital stays, repeated admissions or long-term catheters.

Where this sits in the wider picture

Not sure what the swelling is?

Start with the overview of testicular problems — lumps, swellings, aches and what each of them usually means.

Frequently Asked Questions About Hydroceles

No. They are two different things that both cause scrotal swelling. A hydrocele is a collection of fluid around the testicle. It feels smooth, like a small water balloon, and the swelling stays much the same whether you stand or lie down. A varicocele is a group of enlarged veins. It is often described as feeling like a bag of worms, it usually becomes more obvious when you stand up, and it tends to soften or disappear when you lie flat. A varicocele is also far more likely to sit on the left. Only an examination, usually with an ultrasound scan, can tell you which one you have.

No. A small hydrocele that does not bother you can simply be left alone. Surgery is offered when the swelling is uncomfortable, heavy, large enough to get in the way of everyday life, or when it is causing you distress. Draining a hydrocele with a needle is not a cure: the fluid comes back, usually quite quickly, and the needle can introduce infection. For that reason BAUS does not recommend aspiration as standard treatment.

Expect swelling, bruising and discomfort in the scrotum for several days to a few weeks. A scrotal support and simple painkillers help a great deal in the first week. The stitches dissolve on their own and usually disappear after two to three weeks. You should avoid heavy lifting and strenuous exercise for at least four weeks. Most men return to desk work well before that, but the timing depends on your job and how you feel.

It will feel better, but it will not feel identical to the other side. When the fluid sac is bunched up and stitched, that tissue stays there, so the treated testicle almost always feels bulkier than the untreated one. This is expected rather than a complication, and it is worth knowing before you agree to surgery. What does settle is the weight, the ache and the size of the swelling.

Swelling You Want Properly Explained?

A scrotal swelling deserves an examination and a scan, not guesswork. I will tell you what it is, whether it needs treating, and what happens if you leave it.