Epididymo-orchitis is an inflammation of the epididymis and/or testicle (testis). In adults, epididymo-orchitis is usually due to infection, most commonly from a urine infection or a sexually transmitted infection. A course of antibiotic medicine will usually clear the infection. Full recovery is usual. Epididymo-orchitis complications are uncommon.
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.
In boys who have not reached puberty, symptoms are often not due to an infection. The most common cause at this age is thought to be urine refluxing into the duct that sperm pass down (the ejaculatory duct, or vas deferens). It can also be due to urine infection. Rarely, epididymo-orchitis in children can be a complication of Henoch-Schönlein purpura, a condition caused by inflammation of the blood vessels.
In over-14s, most cases of epididymo-orchitis are due to an infection. Causes of infection include the following:
Germs (bacteria) such as E. coli that cause urine infections 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 years. This is because partial blockage of urine flow becomes more common with increasing age, due to an enlarged prostate gland or narrowing of the urethra (urethral stricture). The urethra is the tube that urine flows out of from the bladder. Partial blockage of urine makes you more prone to develop urine infections.
A sexually transmitted infection 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 testicle (testis).
The mumps virus 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 testicles via the bloodstream. This cause is now uncommon since the measles, mumps and rubella (MMR) immunisation is now routinely given to children.
Epididymo-orchitis can occasionally be a side-effect of a medicine called amiodarone. It normally occurs at doses above 200 mg, especially when the dosage range reaches 400-800 mg.
Symptoms usually develop quickly – over a day or so. The affected epididymis and testicle 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 high temperature (fever) and feel generally unwell.
