Scrotal Swelling: Hydrocele, Varicocele, Spermatocele or Something Else?
Updated: 1 day ago
Most scrotal swelling comes from harmless causes, such as fluid around the testicle (hydrocele), swollen veins (varicocele) or a small cyst (spermatocele). However, sudden severe pain can mean testicular torsion, an emergency. A hard lump inside the testicle also needs prompt checks for cancer.
Medically reviewed by Assoc. Prof. Dr. Tuncay Taş, urologist. Updated October 2026.
This guide helps you understand what each cause feels like and how fast it develops. It also explains which tests confirm it and what treatment looks like. Above all, it shows which signs need urgent care and which can wait.
First, rule out an emergency
Some causes of scrotal swelling cannot wait. In the US and Canada, call 911 or go to the emergency department.
In the UK, go to A&E or call 999. Do this if you have any of the signs below.
Sudden, severe pain in one testicle.
Testicle pain with nausea, vomiting or pain in the belly.
Pain that lasts more than an hour or continues while you rest.
A groin or scrotal bulge that becomes painful, hard and will not go back.
A red, hot, swollen scrotum with fever and feeling very unwell.
Testicular torsion, the main worry, twists the cord that carries blood to the testicle. After about 6 hours without blood flow, the risk of losing the testicle rises sharply. So do not wait to see if the pain settles, and do not drive yourself.
Scrotal swelling causes at a glance
The table compares the common causes. It is a guide, not a diagnosis, because several causes can feel alike. Only an examination and a scan can tell them apart for certain.
Cause | What it usually feels like | Pain | How fast | Urgency |
Hydrocele | Smooth, soft swelling around the whole testicle | Usually none, or a heavy feeling | Slow, over weeks or months | Routine |
Varicocele | Bag of worms above the testicle, usually left side | Dull ache, worse when standing | Slow | Routine |
Spermatocele or epididymal cyst | Small, smooth pea-like lump above and behind the testicle | Usually none | Slow | Routine |
Epididymitis or orchitis | Tender, warm, swollen testicle or epididymis | Moderate to severe | Hours to days | Same day |
Inguinal hernia | Bulge from the groin into the scrotum, bigger on coughing | Mild, unless trapped | Slow, then sudden if trapped | Routine, emergency if trapped |
Testicular torsion | Swollen, high-riding, very tender testicle | Sudden and severe | Minutes to hours | Emergency |
Testicular cancer | Hard, painless lump inside the testicle | Usually none, sometimes an ache | Weeks to months | Prompt, within 2 weeks |
Injury | Bruising and swelling after a blow | Varies | Immediate | Same day if severe |
Hydrocele: fluid around the testicle
A hydrocele is a collection of fluid in the thin sac around the testicle. It feels like a smooth, soft balloon, and the testicle may be hard to feel inside it. Usually, it causes no pain, although a large one can feel heavy or drag.
In baby boys, hydroceles are common and often disappear within the first year. In adults, they can follow an injury, an infection or surgery, but often there is no clear cause. A light held against the scrotum shines through a hydrocele, because it contains clear fluid.
Your urologist can simply watch a small hydrocele that causes no trouble. Surgery makes sense when the swelling is large, uncomfortable or growing. The hydrocele surgery page explains the operation and recovery.
Varicocele: swollen veins above the testicle
A varicocele is a group of swollen veins in the cord above the testicle, much like varicose veins in the leg. Classically, it feels like a bag of worms. It also tends to shrink when you lie down and fill up when you stand.
Varicoceles affect about 15 in 100 men, and most appear on the left side. Many cause no symptoms at all. Others cause a dull ache that gets worse after standing, exercise or a long day.
Why a varicocele matters for fertility
A varicocele can warm the testicle and lower sperm quality. For this reason, urologists often find one when a couple has trouble conceiving. Treatment can raise sperm counts in selected men, especially with an abnormal semen test.
The usual repair is a microscopic varicocelectomy, which ties off the swollen veins through a small groin cut. If a semen test showed no sperm at all, our guide to obstructive and non-obstructive azoospermia explains the next steps.
A varicocele on the right side only
A new varicocele on the right side alone is unusual. Similarly, a varicocele that does not empty when you lie down is unusual.
In both cases, a urologist may then order a scan of the belly. This checks for pressure on the veins higher up.
Spermatocele and epididymal cyst
A spermatocele is a small cyst full of fluid. It grows from the epididymis, the coiled tube behind the testicle. An epididymal cyst is very similar.
Both feel like a smooth pea above and behind the testicle, clearly separate from it.
These cysts are common and harmless, so they rarely need more than a scan to confirm them. In addition, they do not affect testosterone and rarely affect fertility. Most need no treatment, although surgery can remove one that grows large or uncomfortable.
Epididymitis and orchitis: infection and inflammation
Epididymitis is inflammation of the epididymis, usually from infection. When the testicle also becomes inflamed, doctors call it epididymo-orchitis. The swelling and pain build over hours to days, rather than minutes.
In younger, sexually active men: sexually transmitted infections such as chlamydia and gonorrhoea are the usual cause.
In older men: urine infections often spread from the bladder or prostate, especially with an enlarged prostate.
Mumps orchitis: mumps after puberty can inflame one or both testicles.
Treatment is antibiotics, rest, scrotal support and painkillers. Pain usually eases within a few days, but swelling can take weeks to settle. Partners also need testing and treatment if they may carry the infection.
Torsion or infection?
Torsion and infection can look alike, especially in teenagers and young men. Typically, torsion starts suddenly and severely, often with vomiting. Infection usually builds more slowly, sometimes with burning when passing urine.
Still, only an urgent scan can safely tell them apart, so never assume infection.
Inguinal hernia reaching the scrotum
An inguinal hernia happens when part of the bowel or fatty tissue pushes through a weak spot in the groin. In men, the bulge can travel down into the scrotum. Typically, it gets bigger when you stand, cough or strain, and it may go back when you lie down.
Straining to pass urine may also play a part. In fact, Assoc. Prof. Taş studied the link between urinary symptoms and inguinal hernia. You can find the paper in the sources below.
Therefore, a man with a hernia and a weak stream may need both problems assessed.
A hernia does not heal on its own, so most men eventually need a repair. However, a trapped hernia that turns painful, hard and red is an emergency. In that case, the bowel may lose its blood supply.
Testicular cancer: the lump that needs prompt checks
Testicular cancer usually starts as a painless lump or hardness inside the testicle itself. Some men notice that one testicle has grown or feels heavy. Others only feel a dull ache in the lower belly or scrotum.
It is most common in men aged 15 to 49. Risk also rises after undescended testicles or when a father or brother had it. Importantly, testicular cancer is one of the most treatable cancers, especially when found early.
The main tests are a scrotal ultrasound and blood tumour markers. If the scan shows a tumour, the usual first step is surgery. The surgeon then removes the affected testicle through the groin.
The testicular cancer surgery page explains treatment and follow-up.
Other causes of a swollen scrotum
Injury: a blow can cause bruising or bleeding around the testicle, and a scan rules out a rupture.
After surgery: swelling is common for a few weeks after vasectomy, hernia repair or scrotal surgery.
Fluid retention: heart, kidney or liver disease can swell both sides of the scrotum, often with swollen legs.
Skin infection: a red, hot, painful scrotum with fever needs same-day care, as it can spread quickly.
In young boys: a hernia, a hydrocele and a twisted small appendage on the testicle are common causes.
One side or both sides?
Where the swelling sits gives a useful clue. For example, a swelling on one side points to a local cause, such as a hydrocele, a cyst, a varicocele or a tumour. Swelling on both sides, however, more often comes from fluid retention, an infection that spreads or a recent operation.
Also note whether the swelling sits in the testicle, above it or in the groin. A lump separate from the testicle is usually a cyst or a varicocele. In contrast, a lump within the testicle itself always needs a scan.
Watch, treat or operate?
Not every swelling needs surgery, and some need none at all. In fact, many men only need a clear diagnosis and a plan for follow-up. The table shows how urologists usually decide.
Cause | Watchful waiting is reasonable when | Treatment is advised when |
Hydrocele | It is small, painless and stable | It is large, uncomfortable or growing |
Varicocele | It causes no pain and fertility is not a concern | It aches, the semen test is abnormal or the testicle shrinks |
Spermatocele or cyst | It is small and painless | It grows large or causes discomfort |
Epididymitis | Never, as it needs antibiotics | Always, with antibiotics and rest |
Inguinal hernia | It is small and causes few symptoms, after a surgeon's review | It causes pain, grows or becomes hard to push back |
Solid lump in the testicle | Never | Always, with prompt scans and surgery if confirmed |
How doctors find the cause
Most men need only a short visit and one scan. First, the doctor asks when the swelling started and whether it hurts. Then they examine both sides while you stand and lie down.
Examination: the doctor checks whether the swelling lies in the testicle, above it or in the groin.
Light test: a torch held behind the scrotum shines through fluid, such as a hydrocele or cyst.
Scrotal ultrasound with Doppler: the main test, which shows fluid, solid lumps and blood flow.
Urine and blood tests: these check for infection and, if needed, tumour markers such as AFP, hCG and LDH.
For patients who travel from the US, Canada or the UK, Assoc. Prof. Taş examines the scrotum in person and arranges an ultrasound at the clinic. The treatment plan then rests on that in-person assessment.
How to check your testicles at home
A monthly self-check helps you notice change early. The best time is after a warm bath or shower, when the scrotum is relaxed.
Hold the scrotum in your palm and check each testicle in turn.
Roll each testicle gently between thumb and fingers, feeling for lumps or hard areas.
Find the epididymis, the soft tube at the back, so you know it is normal.
Note any change in size, shape or weight, and see a doctor if it lasts more than 2 weeks.
It is normal for one testicle to hang lower or be slightly larger than the other. Instead, what matters is change over time, so compare each check with the last one.
When to see a urologist
Every new lump or swelling in the scrotum deserves a medical check, even if it does not hurt. Your GP or family doctor can start the assessment, then refer you on. A urologist is the right next step in these situations.
A hard lump inside the testicle, even if painless.
Any swelling that keeps growing, aches or drags.
Trouble conceiving, or a low sperm count, together with a varicocele.
Swelling that has not settled 2 weeks after treatment for infection.
A hernia or hydrocele that limits sport, work or clothing.
To plan an assessment in person, book a consultation with Assoc. Prof. Taş or message the team on WhatsApp. Patients from the US, Canada and the UK receive a personal plan and quote after the consultation. Then the coordinator arranges the days in Istanbul.
Frequently asked questions
What is the most common cause of scrotal swelling?
In adults, the most common causes are a hydrocele, a varicocele, a cyst of the epididymis and infection. Most of these are harmless or easy to treat. Even so, every new swelling deserves a check by a doctor.
When is a swollen testicle an emergency?
Sudden, severe pain in a testicle is an emergency, especially with nausea, vomiting or belly pain. Pain that lasts more than an hour or continues at rest also needs urgent care. These signs can mean testicular torsion, which needs surgery within hours.
How can I tell a hydrocele from a varicocele?
A hydrocele feels like a smooth, soft balloon of fluid around the testicle. A varicocele feels like a bag of worms above the testicle, usually on the left, and often shrinks when you lie down. An ultrasound scan confirms which one it is.
Is a painless lump in the testicle cancer?
Most lumps are not cancer. However, a hard, painless lump inside the testicle itself needs prompt assessment, because testicular cancer often starts this way. Testicular cancer is also one of the most treatable cancers, especially when found early.
Can a hernia cause scrotal swelling?
Yes. An inguinal hernia can push down from the groin into the scrotum. It often gets bigger when you stand or cough and may go back when you lie down. A hernia that becomes painful and cannot go back needs emergency care.
What tests diagnose scrotal swelling?
A doctor first examines the scrotum and may shine a light through it to check for fluid. A scrotal ultrasound with Doppler is the main test. Urine tests check for infection, and blood tumour markers help if the scan shows a solid lump.
Does scrotal swelling go away on its own?
Sometimes. Swelling after a minor injury or a treated infection usually settles within days to weeks. A hydrocele, varicocele or hernia usually stays or slowly grows, so it needs a urologist's opinion.
Sources
About the reviewer
Assoc. Prof. Dr. Tuncay Taş is a urologist in Istanbul with more than 20 years of experience and patients from over 60 countries. He graduated from Istanbul University in 2004, trained at Taksim Training and Research Hospital, completed a uro-oncology and laparoscopy fellowship at Heidelberg University and belongs to the EAU and the Endourological Society. Read his full profile.
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