Definition of Orchitis:

Orchitis is swelling (inflammation) of one or both of the testicles.

Causes, incidence, and risk factors:

Orchitis may be caused by an infection from many different types of bacteria and viruses.

The most common virus that causes orchitis is mumps. It most often occurs in boys after puberty. Orchitis usually develops 4 - 6 days after the mumps begins. Because of childhood vaccinations, mumps is now rare in the United States.

Orchitis may also occur along with infections of the prostate or epididymis.

Orchitis may be caused by sexually transmitted diseases (STD), such as gonorrhea or chlamydia. The rate of sexually transmitted orchitis or epididymitis is higher in men ages 19 - 35.

Risk factors for sexually transmitted orchitis include:

• High-risk sexual behaviors
• Multiple sexual partners
• Personal history of gonorrhea or another STD
• Sexual partner with a diagnosed STD

Risk factors for orchitis not due to an STD include:

• Being older than age 45
• Long-term use of a Foley catheter
• Not being vaccinated against the mumps
• Problems of the urinary tract that occurred at birth (congenital)
• Regular urinary tract infections
• Surgery of the urinary tract (genitourinary surgery)