Hydrocele and Scrotal Swelling | Dr. Theodore Cisu

The short answer: A hydrocele is a painless buildup of fluid around a testicle that makes one side of the scrotum swell. It's common and usually harmless, and it only needs treatment if it's large or bothersome. Any new scrotal swelling should still be checked, because other causes include a spermatocele, a varicocele, a hernia, an infection or a lump in the testicle. Sudden, severe testicle pain can be testicular torsion, and that needs the emergency room right away.

Written by Theodore Cisu, MD, board-certified urologist. There is no AUA guideline specific to hydrocele, so this article is based on patient information from the Urology Care Foundation (the foundation of the American Urological Association), the U.S. National Library of Medicine and published research reviews. Last reviewed November 2026.

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What is a hydrocele?

Each testicle sits inside a thin, two-layered sac. A small amount of fluid normally lets the testicle move freely. A hydrocele forms when extra fluid collects inside that sac.

In baby boys, a hydrocele often comes from a small opening left over from development, and many close on their own. In adults, a hydrocele usually means the lining makes more fluid than it absorbs. Sometimes it follows an injury, an infection or surgery in the area. Often there's no clear cause.

Symptoms of a hydrocele

• Painless swelling on one or both sides of the scrotum
• A smooth, soft feel, a bit like a water balloon
• A heavy or dragging feeling, often worse at the end of the day
• Swelling that slowly grows over months or years
• With larger hydroceles, trouble with clothing, sitting, walking or exercise

A hydrocele by itself usually doesn't hurt. If you have real pain, redness or fever, something else may be going on.

Other causes of scrotal swelling

Several conditions can look like a hydrocele from the outside. Here are the most common.

Spermatocele (epididymal cyst)

A fluid-filled cyst in the epididymis, the coiled tube that sits above and behind the testicle. It often feels like a small, separate ball next to the testicle. Most are harmless and painless.

Varicocele

Enlarged veins in the scrotum, sometimes described as feeling like a "bag of worms." They're more common on the left side and more noticeable when standing. A varicocele can cause a dull ache. In some men it's linked to fertility problems, and in teens it can affect how the testicle grows.

Inguinal hernia

Tissue or a loop of intestine pushes through a weak spot in the groin and down into the scrotum. The bulge may get bigger when you cough or strain and shrink when you lie down. Hernias are usually repaired by a general surgeon.

Epididymitis or orchitis

Infection or inflammation of the epididymis or testicle. This tends to be painful, with redness, warmth and sometimes fever. It's usually treated with antibiotics.

A lump on the testicle

A firm lump on the testicle itself is the finding that matters most to check. Testicular cancer is most common in younger men, and it's very treatable when found early. A large hydrocele can make the testicle hard to feel, which is one reason an ultrasound is often done.

When scrotal swelling is an emergency

Go to the emergency room or call 911 if you have:

• Sudden, severe pain in a testicle or the scrotum, especially with nausea or vomiting
• A testicle that suddenly sits higher than usual or at an odd angle
• Significant pain or swelling after an injury
• A painful, hard bulge in the groin or scrotum that won't go back in
• Fever with a red, hot, painful scrotum

Sudden testicle pain can be testicular torsion. The testicle twists on its cord and cuts off its own blood supply. Time matters: according to the Urology Care Foundation, lasting damage can begin after about six hours. Torsion is most common in teens and young men, but it can happen at any age. Don't wait to see if the pain passes, and don't wait for an office visit.

How is scrotal swelling diagnosed?

• Exam: Your doctor feels which part of the scrotum is swollen and checks your groin while you cough. Shining a light through the scrotum can show whether the swelling is clear fluid.
• Scrotal ultrasound: A painless test with no radiation. It shows the testicle, any fluid, cysts or enlarged veins, and the blood flow to the testicle. It's the standard test for most new scrotal swelling.
• Urine and blood tests: A urine test helps if infection is a possibility. Blood tests may be ordered if there's a lump in the testicle.

Hydrocele treatment options

The right choice depends on how big the hydrocele is, how much it bothers you and what the ultrasound shows.

Watchful waiting

If your hydrocele is small, doesn't bother you and the testicle looks normal on ultrasound, you don't need to do anything. A hydrocele doesn't damage the testicle. In adults it usually doesn't go away on its own, so you can choose to treat it later if it grows or becomes uncomfortable.

Hydrocelectomy (surgery)

Hydrocelectomy is the main treatment for a hydrocele that bothers you. It's an outpatient procedure done under anesthesia, and most people go home the same day. Through a small incision, usually in the scrotum, the fluid is drained and the sac lining is removed or folded back so fluid can't collect again.

What to expect afterward:

• Swelling and bruising are normal and can take several weeks to settle
• Snug, supportive underwear and ice packs help with comfort
• Pain usually improves within the first week
• You'll avoid heavy lifting and strenuous activity for a few weeks

Possible risks include bleeding or a blood collection in the scrotum, infection, prolonged swelling and, uncommonly, the hydrocele coming back. Dr. Cisu performs hydrocelectomy and will go over the details with you.

Needle drainage and sclerotherapy

The fluid can be drained with a needle, sometimes followed by injecting a medicine that helps the sac lining seal. It's less invasive and recovery is quicker. A Cochrane review found that the fluid is much more likely to come back after this approach than after surgery. Drainage alone almost always refills. This is an option your urologist can discuss, for example if surgery isn't a good fit for you.

Treating other causes

• Spermatocele: Usually just watched. It can be removed surgically if it's large or uncomfortable. Dr. Cisu performs spermatocele removal.
• Varicocele: Treated when it causes pain, affects fertility or affects testicle growth in a teen. Options include surgery and a procedure that blocks the vein from the inside. Your urologist can discuss these, and Dr. Cisu can coordinate referral to a subspecialist when appropriate.
• Hernia: Referred to a general surgeon for repair.
• Lump on the testicle: Needs prompt evaluation by a urologist, with an ultrasound and blood tests to plan next steps.

When to see a urologist

• Any new lump or swelling in the scrotum
• Swelling that is growing, heavy or getting in the way of daily life
• You can't clearly feel your testicle because of the swelling
• A dull ache that doesn't go away
• Follow-up after an emergency room visit for scrotal pain
• You're considering surgery or want a second opinion

Seeing Dr. Cisu for scrotal swelling

You can start with a telehealth visit from anywhere in Virginia. Our office can request your ultrasound and records ahead of time so Dr. Cisu has reviewed them before you talk. Second opinions are welcome. When an exam or procedure is needed, Dr. Cisu sees patients at clinics in Charlottesville and Fishersville. No referral is needed. Book an appointment.

Frequently asked questions

Is a hydrocele dangerous?

Usually not. A hydrocele is a collection of fluid and doesn't harm the testicle. The main reason to have it checked is to make sure nothing else, such as a lump on the testicle or a hernia, is causing the swelling.

Will a hydrocele go away on its own?

In babies, many hydroceles go away during the first year or so. In adults, they usually stay the same or slowly grow. Many men live with a small hydrocele for years without any trouble.

Can a hydrocele affect fertility or testosterone?

In most cases, no. A simple hydrocele doesn't usually affect how the testicle makes sperm or testosterone. A varicocele is a different condition that can affect fertility in some men.

How long is recovery from hydrocele surgery?

Pain usually improves within the first week. Swelling can take several weeks to go down. Most men avoid heavy lifting and strenuous exercise for a few weeks, based on their surgeon's advice.

Can a hydrocele come back after surgery?

It's uncommon after hydrocelectomy, but it can happen. Fluid is much more likely to return after needle drainage.

How do I know if it's torsion and not a hydrocele?

A hydrocele is usually painless and builds slowly. Torsion usually causes sudden, severe pain. You can't safely tell the difference at home, so treat sudden testicle pain as an emergency and go to the ER.

Does scrotal swelling mean cancer?

Most scrotal swelling is not cancer. Because a lump on the testicle can be cancer, any new swelling should be examined, usually with an ultrasound.

Sources

• Urology Care Foundation. Hydroceles and Inguinal Hernia.
• Urology Care Foundation. Testicular Torsion.
• Cochrane Database of Systematic Reviews. Aspiration and sclerotherapy versus hydrocoelectomy for treating hydrocoeles (2014).

This article is for general education and isn't a substitute for medical advice. If you have sudden, severe pain in a testicle or the scrotum, call 911 or go to the nearest emergency room.