What is epididymo-orchitis?

  • Epididymitis means inflammation of the epididymis (the structure next to the testis that is involved in making sperm).
  • Orchitis means inflammation of a testis (testicle).

As the epididymis and testis lie next to each other, it is often difficult to tell if the epididymis, the testis, or both are inflamed. Therefore the term epididymo-orchitis is often used.

What causes epididymo-orchitis?

Most cases are due to an infection. Causes of infection include the following:

A complication from a urine infection

Bacteria that cause urine infections such as E. coli can sometimes track down the vas deferens to cause an epididymo-orchitis. This can happen at any age and is the most common cause of epididymo-orchitis in men aged over 35. This is because partial blockage of urine flow becomes more common with increasing age, due an enlarged prostate or urethral stricture (narrowing of the urethra). Partial blockage of urine makes you more prone to develop urine infections. A complication of a urine infection is also the usual cause of epididymo-orchitis in young boys.

Sexually transmitted infection

This is the most common cause of epididymo-orchitis in young men (but can occur in any sexually active man). It most commonly occurs with chlamydial and gonorrhoeal infections. In men, these infections typically infect the urethra to cause a urethritis. However, sometimes the infection can track down the vas deferens to the epididymis and testis.

The mumps virus

This used to be a common cause. Most people with mumps develop swelling of the parotid salivary glands. However, mumps in boys also causes epididymo-orchitis in about 1 in 5 cases. The virus gets to the testes via the bloodstream. This cause is now uncommon since the measles, mumps and rubella (MMR) immunisation is now routinely given to children.

An operation to the prostate or urethra

This may allow bacteria into the urethra which may track down to the testes. Epididymo-orchitis used to be a common complication after prostatectomy (removal of the prostate). This is now rare due to better surgical techniques.


Epididymo-orchitis can occasionally be a side-effect of a drug called amiodarone. It normally occurs at doses above 200 mg.

Uncommon causes

Other viral infections are uncommon causes of epididymo-orchitis. Infection from other parts of the body can, rarely, travel in the blood to the testes, such as tuberculosis (TB) and brucellosis. When this happens it is usually in people who have a problem with their immune system (for example, people with AIDS). Schistosomiasis is a tropical infectious disease that can cause epididymo-orchitis. Men with Beh├žet’s disease may develop inflamed testes to cause a non-infective epididymo-orchitis. Injury to the scrotum can cause inflammation of the epididymis and testis.

Who gets epididymo-orchitis?

Epididymo-orchitis occurs in about 1 in 1,000 males. It is common in men aged 15-30, and in men aged over 60. It does not occur very often before puberty. About 3 in 10 boys who get mumps after puberty develop orchitis. Your risk of getting epididymo-orchitis is increased if you have a catheter or other instruments inserted into the urethra.

What are the symptoms of epididymo-orchitis?

Symptoms usually develop quickly – over a day or so. The affected epididymis and testis swell rapidly, and the scrotum becomes enlarged, tender, and red. It can be very painful.

There may be other symptoms if the epididymo-orchitis is a complication from another infection. For example: pain on passing urine if you have a urine infection; a discharge from the penis if you have a urethral infection; etc. As with any infection, you may have a fever and feel generally unwell.

Are any tests needed?

Tests to look for infecting bacteria

A urine test will usually be done if a urine infection appears to be the root cause. A swab of the urethra or other tests may be done if a sexually transmitted infection is thought to be the root cause. Sexual partners of people with epididymo-orchitis caused by a sexually transmitted disease will also need testing.

See separate leaflets called ‘Chlamydia – Genital’, ‘Urethritis and Urethral Discharge in Men’ and ‘Gonorrhoea in Men’ for details of these infections.

Tests of the urinary tract

Tests to look into the urethra and bladder may be needed if a urine infection is the cause, and this is thought to be due to partial blockage of urine flow or other urinary tract abnormalities.

See separate leaflets called ‘Urine Infection in Men’ and ‘Urine Infection in Children’ for details.

What is the treatment for epididymo-orchitis?

A course of antibiotics is usually advised as soon as epididymo-orchitis is diagnosed. These normally work well. Pain usually eases within a few days, but swelling may take a week or so to go down, sometimes longer. The choice of the antibiotic depends on the underlying cause of the infection.

If a sexually transmitted infection is the cause then you should not have sex until treatment and follow-up have been completed. Sexual partners of men with epididymo-orchitis caused by a sexually transmitted disease may also need antibiotic treatment.

Antibiotics do not kill viruses and they are not needed if a viral infection is the cause. For example, mumps.

You may find that supporting underwear helps to ease the pain. Painkillers and ice packs will also ease the pain.

Are there any complications from epididymo-orchitis?

Most people recover fully and complications are uncommon. Possible complications include:

  • An abscess (a collection of pus due to infection) occasionally develops in the scrotum. This may need a small operation to drain the pus.
  • Reduced fertility in the affected testis, especially in cases caused by the mumps virus.
  • An ongoing (chronic) inflammation occasionally develops.
  • Rarely, serious damage to the testis may occur and result in gangrene (dead tissue) in the testis that needs to be surgically removed.

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