Orchitis is infection of the testes, most often by a virus such as mumps..
Orchitis can occur when the epididymis is infected, as part of epididymo-orchitis. When infection involves only the testes, it is called orchitis. Orchitis is most often caused by a virus, usually the mumps virus. Rarely, it is caused by other infections. About 20 to 25% of men who have mumps develop orchitis. Most cases of mumps orchitis occur in boys younger than 10 years.
Orchitis may cause the testis to shrink but usually does not decrease production of the male hormone testosterone. Orchitis may diminish the person's fertility, particularly if it affects both testes and/or occurs after puberty. However, infertility is rare.
Orchitis develops between 4 and 7 days after the salivary gland swelling. The testis swells and is painful. Sometimes both testes are affected. The person may also have fever, nausea, headache, and muscle aches.
Orchitis is diagnosed by physical examination, urinalysis, and sometimes Doppler ultrasonography, which assesses blood flow to the testes. Sometimes blood tests are done to identify the mumps virus.
Orchitis is usually treated with bed rest, pain relievers, and ice packs applied to the scrotum.
Last full review/revision June 2013 by Patrick J. Shenot, MD