The male reproductive system makes, stores and moves sperm. Testicles produce sperm. Fluid from the seminal vesicles and prostate gland combine with sperm to make semen. The penis ejaculates semen during sexual intercourse.
Orchitis can be caused by a bacterial or viral infection. Sometimes a cause of orchitis can't be determined.
Bacterial orchitis
Most often, bacterial orchitis is associated with or the result of epididymitis. Epididymitis usually is caused by an infection of the urethra or bladder that spreads to the epididymis.
Often, the cause of the infection is an STI. Other causes of infection can be related to having been born with abnormalities in your urinary tract or having had a catheter or medical instruments inserted into your penis.
Viral orchitis
The mumps virus usually causes viral orchitis. Nearly one-third of males who contract the mumps after puberty develop orchitis, usually four to seven days after onset of the mumps.