Orchitis is infection of the testes, typically with mumps virus. Symptoms are testicular pain and swelling. Diagnosis is clinical. Treatment is symptomatic. Antibiotics are given if bacterial infection is identified.

Isolated orchitis (ie, infection localized to the testes) is nearly always viral in origin, and most cases are due to mumps. Rare causes include congenital syphilis, TB, leprosy, echovirus infection, lymphocytic choriomeningitis, coxsackievirus infection, infectious mononucleosis, varicella, and infection with group B arborviruses. Most bacterial causes also involve an epididymis (epididymo-orchitis—see Penile and Scrotal Disorders: Epididymitis).

Orchitis develops in 20 to 25% of males with mumps; 80% of cases occur in patients < 10 yr. Two thirds of cases are unilateral and one third bilateral. Sixty percent of patients with mumps orchitis develop testicular atrophy in at least one testis. Atrophy is unrelated to fertility or to the severity of the orchitis. The incidence of tumor does not appear to be increased, but unilateral disease diminishes fertility in one fourth of men after unilateral mumps orchitis and in two thirds of men who have had bilateral disease.

Symptoms and Signs

Unilateral mumps orchitis develops acutely between 4 and 7 days after parotid swelling in mumps. In 30% of cases, the disease spreads to the other testis in 1 to 9 days. Pain may be of any degree of severity. In addition to pain and swelling of the testes, systemic symptoms may develop, such as malaise, fever, nausea, headache, and myalgias. Testicular examination reveals tenderness, enlargement, and induration of the testis and edema and erythema of the scrotal skin.

Other infectious agents cause similar symptoms with speed of onset and intensity related to their pathogenicity.

Diagnosis

• Clinical evaluation and selective testing

History and physical examination usually indicate the diagnosis. Urgent differentiation of orchitis from testicular torsion and other causes of acute scrotal swelling and pain is accomplished with color Doppler ultrasonography. Mumps can be confirmed by serum immunofluorescence antibody testing. Other infectious agents may be identified by urine culture or serology.

Treatment

• Analgesics

Supportive care with analgesics and hot or cold packs is sufficient if bacterial infection has been ruled out. Bacterial causes are treated with appropriate antibiotics. Urologic follow-up is recommended.

Last full review/revision December 2012 by Patrick J. Shenot, MD

Content last modified January 2013