Epididymitis vs testicular torsion: telling two causes of testicular pain apart

A painful, swollen testicle has more than one possible cause, and the two most discussed are epididymitis and testicular torsion. They matter in different ways. Epididymitis is an inflamed epididymis, the tube behind the testicle, and is usually an infection that antibiotics clear. Testicular torsion is the twisting of the spermatic cord, which supplies blood to the testicle. It is a surgical emergency in which minutes and hours count.

Because the symptoms overlap, you cannot reliably decide which one you have at home. The practical rule drawn from the NHS and hospital guidance is simple: sudden, severe testicular or lower tummy pain should be seen in an emergency department straight away. It is far better to be told it was epididymitis than to lose a testicle by waiting.

The NHS says epididymitis is where the epididymis, a tube behind the testicles, becomes swollen and painful. It is often caused by an infection and usually treated with antibiotics. In younger men under 35 it is more often due to a sexually transmitted infection such as chlamydia or gonorrhoea; in men over 35 the main cause is usually a urine infection. Less common causes include mumps, tuberculosis, the heart-rhythm medicine amiodarone, a groin injury and Behçet's disease.

Cambridge University Hospitals explains that testicular torsion occurs when the cord carrying blood to the testicle twists, which can range from half a turn to two full turns. The twisting cuts off the blood supply and causes pain and swelling. Some boys and men have a testicle that is not firmly attached at the base of the scrotum (called bell clapper deformity), which lets it twist more freely, but in many there is no apparent cause. Torsion may happen during exercise or sleep, or after an injury, and nothing the person did or did not do causes it.

The picture below combines what the NHS says for epididymitis with what the hospital leaflets say for torsion. Sharing a symptom is exactly why examination is needed.

For epididymitis, the NHS says that you will usually need tests to find the cause. These may include a groin examination, a swab of the tube that carries urine out of the body, urine and blood tests, and a rectal examination to check for prostate problems. Your recent sexual contacts may be offered STI testing if an infection is found.

For suspected torsion, the approach is different, because time is the main constraint. Guy's and St Thomas' says that at hospital the team takes a history, examines the scrotum and tests a urine sample for infection and blood, and that more tests are not usually helpful because of the urgency. It also states that it is difficult to be completely certain that someone has torsion, and the doctors might recommend scrotal exploration surgery if they think it is likely.

A scan is not a safe shortcut. The same leaflet says that a scan is not completely accurate and might delay surgery and risk loss of the testicle, and that watching and waiting also risks losing the testicle. It adds that in 1 in 10 people having this type of surgery no twist is found, in which case the cut is stitched and no further treatment is needed. That figure helps to explain why surgeons accept some operations that turn out not to be torsion: the cost of missing a true torsion is far higher.

Epididymitis is treated with antibiotics, given as injections, tablets or both. The NHS stresses finishing the whole course even if you feel better, and says you should start to feel better within a few days although full recovery may take up to 3 months. Painkillers such as paracetamol or ibuprofen, a cold pack and supportive underwear can help; the NHS also asks people with a history of seizures to check with a pharmacist before taking an NSAID alongside some of the antibiotics used. If an STI is the cause, it says to avoid sex until treatment is finished or for 7 days after.

Torsion is treated by an operation under general anaesthetic to untwist the testicle. Guy's and St Thomas' explains that if the testicle is healthy it is stitched in place to stop it twisting again, and the other side is usually stitched as well. If the testicle is too badly damaged to recover, it may need to be removed. Most people go home the same day or the day after. Cambridge University Hospitals notes that one testicle is sufficient for hormone production and fertility does not usually suffer long term.

Call 999 or go to A&E for sudden, unbearable pain in the testicles or tummy, and do not drive yourself there. For a lump, swelling, a change in shape, one testicle becoming bigger than the other, or aching that does not go away, the NHS says to see a GP, because lumps can be a sign of testicular cancer, which is easier to treat when found early. A sexual health clinic can also treat epididymitis and many offer walk-in services.

If you have been treated for epididymitis and have not improved, return for review. The NHS says a person still with symptoms after the expected recovery period may be referred for further tests.