Hydrocele: Why the Scrotum Swells and How It's Treated

Noticed painless swelling in one side of the scrotum? It's often a hydrocele — a common, usually harmless build-up of fluid around the testicle. Here's what causes it, how doctors confirm the diagnosis, and what modern hydrocelectomy surgery involves.

What Is a Hydrocele?

A hydrocele is a fluid-filled sac that forms around a testicle, causing the scrotum to swell — sometimes noticeably, sometimes only slightly. It develops when fluid accumulates in the thin sheath (tunica vaginalis) surrounding the testicle. In newborns, hydroceles are common and usually resolve on their own within the first year of life, as the small passage connecting the abdomen and scrotum closes naturally. In adults, hydroceles typically develop due to injury, infection, inflammation, or fluid drainage problems within the scrotum, though sometimes there's no clear identifiable cause.

There are two main types: a communicating hydrocele, where fluid can flow between the abdomen and scrotum through an open passage (increasing and decreasing with activity or position), and a non-communicating hydrocele, where the fluid is sealed within the scrotal sac and stays fairly constant in size.

Signs and Symptoms

• Painless swelling in one or both sides of the scrotum
• A feeling of heaviness or pressure in the scrotum
• Swelling that may increase throughout the day and decrease overnight
• In larger hydroceles, discomfort or difficulty with normal activity

Because testicular swelling can also signal more serious issues like a hernia or tumor, any new scrotal swelling should always be evaluated by a doctor rather than assumed to be a simple hydrocele.

Diagnosis

A physical exam is usually the first step — your doctor will check whether light passes through the swelling (a process called transillumination), which is characteristic of fluid-filled hydroceles. An ultrasound is often used to confirm the diagnosis, rule out a hernia or tumor, and assess the testicle underneath.

Treatment: When Is Surgery Needed?

Small, painless hydroceles that aren't bothersome often don't need treatment and can simply be monitored. Surgery — called hydrocelectomy — is recommended when the hydrocele is large, uncomfortable, cosmetically concerning, or associated with an underlying hernia. The procedure typically takes around 30 to 45 minutes under general or spinal anesthesia. The surgeon makes a small incision, drains the fluid, and either removes or folds back the sac lining to prevent recurrence. Most patients go home the same day.

Recovery and Aftercare

• Mild swelling and bruising for the first week is expected
• A supportive undergarment (jockstrap) reduces discomfort and swelling
• Most people return to light activity within a few days and full activity within 2–3 weeks
• Follow-up visits confirm proper healing and rule out recurrence

The Takeaway

Hydroceles are common, generally harmless, and highly treatable when they do need attention. If you notice scrotal swelling, a prompt evaluation ensures the right diagnosis and, if needed, a straightforward path to resolving it.