Quick answer. A hydrocele is a build-up of fluid around the testicle that causes painless scrotal swelling, common in newborns and older men. It is usually harmless, but any sudden painful swelling must be treated as a possible torsion and seen urgently.
A hydrocele is a collection of fluid in the sac surrounding a testicle, leading to soft, usually painless swelling of the scrotum. It is one of the more common causes of scrotal swelling and affects both newborn babies and adult men, particularly as they get older. In most cases a hydrocele is harmless and does not threaten fertility or general health.
This guide explains what a hydrocele is, how it differs from other scrotal lumps, how it is diagnosed and when treatment is needed. Importantly, it also covers the warning signs that point away from a simple hydrocele – because sudden, painful scrotal swelling can signal testicular torsion, a true emergency.
At a glance
| Feature | Typical hydrocele | Needs urgent care |
|---|---|---|
| Onset | Gradual | Sudden |
| Pain | Painless or mild heaviness | Sudden severe testicular pain |
| Associated symptoms | None | Nausea, vomiting, fever, redness |
| The swelling | Soft, fluid-filled, transilluminates | Tender, hard or rapidly enlarging |
| What to do | See a GP or urologist | Go to A&E / call <strong>995</strong> now |
What is a hydrocele?
A hydrocele is a build-up of clear fluid within the tunica vaginalis, the thin sac that surrounds each testicle. The extra fluid makes the scrotum swell on one or both sides. The swelling is typically soft and painless, and it often lights up when a doctor shines a light through it (transillumination), which helps distinguish it from a solid lump.
Hydroceles are common in newborn boys, where they usually clear up on their own within the first year of life. In adult men, especially older men, they can develop gradually and may persist or slowly enlarge. A hydrocele itself is generally harmless.
Symptoms & signs
The main feature is painless scrotal swelling. You might notice:
- A soft, smooth swelling on one or both sides of the scrotum
- A feeling of heaviness or dragging if the hydrocele is large
- Swelling that may be smaller in the morning and larger by the end of the day
- No pain, redness or fever in a simple hydrocele
If the swelling becomes painful, tender, red or appears suddenly, that is not typical of a simple hydrocele and needs prompt assessment.
Causes & risk factors
The cause differs between babies and adults:
- In newborns: a small passage between the abdomen and scrotum that normally closes before birth stays open, allowing fluid through. These usually resolve naturally.
- In adults: an imbalance between fluid produced and absorbed in the sac. This can follow inflammation, infection or injury of the testicle or epididymis, and sometimes no clear cause is found.
Risk factors in adults include older age, scrotal injury, infection and inflammation. Occasionally a hydrocele develops alongside another scrotal condition, which is why assessment is worthwhile.
How it is diagnosed
A doctor can often recognise a hydrocele from examination alone, but a scan is commonly used to confirm it and rule out other causes.
- Physical examination, including transillumination (shining a light through the swelling)
- Scrotal ultrasound to confirm fluid and check the testicle is normal underneath
- Urine tests or blood tests if infection is suspected
Ultrasound is especially useful because it confirms the swelling is fluid and not a solid mass, giving reassurance and guiding treatment.
Treatment options
Many hydroceles need no treatment at all:
- Watchful waiting: infant hydroceles usually resolve on their own within the first year, and small, painless adult hydroceles can simply be monitored.
- Surgery (hydrocelectomy): considered when a hydrocele is large, uncomfortable, unsightly or getting bigger. The surgeon drains the fluid and repairs the sac to stop it returning.
- Aspiration: drawing off the fluid with a needle is sometimes used, but the fluid often comes back, so surgery is generally preferred for a lasting result.
Where surgery is medically indicated, MediSave and MediShield Life may help with the cost in Singapore; check eligibility with your hospital rather than relying on a single quoted figure.
When to see a doctor & which specialist
See a doctor for any new or persistent scrotal swelling so the cause can be confirmed, and arrange review if a hydrocele is enlarging, uncomfortable or you are simply unsure what the lump is. Any solid lump needs assessment to exclude other causes.
Go to A&E or call 995 immediately if you have sudden severe testicular pain, with or without swelling – this could be testicular torsion (a twisted testicle), which is an emergency and must be treated within hours to save the testicle. Sudden painful swelling with fever or redness also needs urgent review.
For diagnosis and treatment of a hydrocele, see a urologist – browse the best urologists in Singapore.
What to expect at the appointment
Assessment for a hydrocele is usually quick and reassuring. The doctor will examine the scrotum, often shining a light through the swelling, because a fluid-filled hydrocele lights up (transilluminates) while a solid lump does not. A scrotal ultrasound is commonly arranged to confirm the fluid and check that the testicle underneath is normal. If an infection or inflammation is suspected, urine or blood tests may be done. Bring a note of how long the swelling has been present and whether it changes through the day, as this helps the doctor.
Recovery after hydrocele surgery
If surgery (hydrocelectomy) is needed, it is usually a day procedure. Afterwards you can expect some swelling and bruising for a week or two, which scrotal support, ice packs and simple pain relief help. Most men return to light activities within days and avoid heavy lifting and strenuous exercise for a few weeks, as advised by their surgeon. Where surgery is medically indicated, MediSave and MediShield Life may help with the cost in Singapore; check eligibility with your hospital rather than relying on a quoted figure.
Common questions
Will an infant’s hydrocele need an operation?
Most hydroceles in babies clear on their own within the first year of life. If one persists beyond that or is linked to a hernia, a doctor may recommend a small repair.
Can a hydrocele come back after being drained?
Draining with a needle (aspiration) often allows the fluid to return, which is why surgery is usually preferred for a lasting result.
Related guides
- Best Urology Clinics in Singapore — our editorial shortlist
- urology clinics directory
- Ovarian cyst
- Infant colic
- Nipah virus
- Varicocele
- Epididymitis
Sources
- NHS – Hydrocele
- Mayo Clinic – Hydrocele
- HealthHub Singapore – Men's health
- SingHealth – Conditions & treatments
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