The short answer
A lump you can feel needs a GP appointment. Sudden severe pain in a testicle needs A&E now. The NHS treats these as separate problems, and an ultrasound usually settles the lump.
The NHS says lumps and swellings in the testicles are not usually caused by anything serious, but should always be checked by a GP.
The NHS lists a lump, swelling, a change in shape, a change in how the testicles feel, one testicle larger than the other, or lasting aching or discomfort as reasons to see a GP.
The NHS says to go to A&E immediately or call 999 for sudden severe pain in a testicle, pain with feeling or being sick or tummy pain, or pain lasting more than an hour or continuing at rest.
NCI lists testicular cancer symptoms as a painless lump or swelling, a change in how the testicle feels, a dull ache in the lower abdomen or groin, sudden fluid build-up in the scrotum, and pain or discomfort.
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The full explanation.
Two problems, two clocks
Search results mix these up constantly, so it helps to separate them at the start.
A lump you can feel, with no pain, is a booking. The NHS lists it under non-urgent advice: see a GP.
Sudden severe pain in one testicle is not a booking. The NHS says to go to A&E immediately or call 999. Those are different problems with different causes, and treating one like the other wastes time in both directions.
The pain that cannot wait
The NHS says to go to A&E immediately or call 999 if you have:
- sudden, severe pain in a testicle.
- testicle pain along with feeling sick, being sick, or pain in your tummy.
- testicle pain that has lasted more than an hour, or continues when you are resting.
It says these can be signs of a serious problem that needs hospital treatment as soon as possible. The usual concern is torsion, a twist that cuts off the blood supply.
The NHS adds a practical note: do not drive yourself to A&E. Ask someone to drive you, or call 999 for an ambulance, and bring any medicines you take.
What the NHS says about a lump
For everything that is not sudden pain, the NHS list is a see-a-GP list:
- a lump in your testicles.
- swollen testicles.
- a change in the shape of your testicles.
- a change in the way your testicles feel.
- one testicle that has become bigger than the other.
- aching or discomfort that does not go away.
Its framing is worth repeating. Lumps and swellings are not usually caused by anything serious, but you should always get them checked. It also warns against trying to self-diagnose the cause.
The usual explanations
The NHS names two straight away. A build-up of fluid, called a cyst or hydrocele, and swollen veins in the testicles, called a varicocele. A varicocele often feels like a small bag of worms and can ache more when standing.
Add infection and inflammation behind the testicle, an old sports knock, and a hernia in the groin. Many need no treatment at all. The NHS says you might not need any if the lump is not causing problems and is not getting worse.
What testicular cancer feels like
NCI lists these symptoms, and says they may be caused by testicular cancer or by other conditions:
- a painless lump or swelling in either testicle.
- a change in how the testicle feels.
- a dull ache in the lower abdomen or the groin.
- a sudden build-up of fluid in the scrotum.
- pain or discomfort in a testicle or in the scrotum.
Pain is on that list, but painless is the classic. A firm lump that does not hurt is not reassuring, and that is the single most useful thing to know here.
The scan that settles it
The NHS says the GP may look at and feel your testicles, shine a torch through the scrotum to check for a fluid build-up, and refer you for an ultrasound scan.
An ultrasound is quick and painless: gel, a handheld probe, no needles. It separates solid from fluid, which answers most of the question in one appointment.
Between now and then, checking the same spot twenty times a day will not add information. Learn what is normal for you, including the soft cord behind each testicle that gets mistaken for a lump. How Cancer Is Diagnosed explains what follows if the scan finds something solid.
Sources
Words to know
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Common questions
Does a lump mean cancer?
Usually not. The NHS says most testicle lumps are caused by something less serious, such as a fluid-filled cyst or swollen veins in the testicles (varicocele). It still asks you to see a GP about every one.
Is a lump an emergency?
No. The NHS lists a lump under non-urgent advice: see a GP. What it does treat as an emergency is sudden severe pain in a testicle, pain with nausea, vomiting or tummy pain, or pain lasting more than an hour.
What does the scan involve?
A scrotal ultrasound. Gel and a small handheld probe, no needles, and it shows whether a lump is solid or fluid. The NHS says the GP may refer you for one after examining you.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
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Your next step
Write down timing, severity, changes, and questions before you talk with a clinician.
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Sources last checked: 2026-08-09 what this meansLast updated: 2026-08-13Next planned review: 2027-07-20
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Editorial review complete — This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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