A hydrocele (fluid around the testicle) is a collection of clear fluid inside the tunica vaginalis (the thin sac that surrounds the testicle). The fluid makes the scrotum swell on one or both sides. Most hydroceles are soft and painless, and they are very common — in adults they often develop slowly over months to years.
Non-communicating hydrocele
The sac is closed off, so fluid simply builds up around the testicle. This is the usual type in adults. The size may stay steady or slowly grow.
Communicating hydrocele
A small channel stays open to the abdomen, so fluid moves in and out. The swelling often changes size during the day — larger when standing or active, smaller after lying down. This type is more common in infants but can occur in adults.
Common symptoms
- Painless scrotal swelling — the most common sign, on one or both sides
- A feeling of heaviness or fullness in the scrotum
- Size changes — some hydroceles grow larger over time or fluctuate through the day
- Discomfort or a dragging sensation when the hydrocele becomes large; usually there is little or no sharp pain
How a hydrocele is diagnosed
Your urologist can usually diagnose a hydrocele with a simple physical exam. A quick test called transillumination (shining a light through the scrotum) makes fluid glow, which helps tell a hydrocele apart from a solid lump. A scrotal ultrasound (a painless imaging test) is often used to confirm the diagnosis and make sure the testicle underneath is healthy.