Epididymitis is an inflammation of the epididymis, the tubular structure that connects the testicle with the vas deferens.

Acute epididymitis causes swelling of the scrotum, pain in the testicles, and sometimes a fever of up to 6 weeks duration or less (usually with a gradual onset over several days).

If not treated, or in some other cases, the condition can become chronic. In chronic cases, there is usually no swelling, but simply pain.

The incidence is approximately 600,000 cases per year. The highest prevalence is in young men 19 to 35 years of age. The disorder is a major cause of hospital admissions in the military (causing approximately 20% of admissions).

Epididymitis is usually caused by spread of infection from the urethra or the bladder. The most common organisms involved in the condition in young heterosexual men are gonorrhoea and chlamydia. In children and older men, typical uropathogens, such as coliform organisms (E. coli), are much more common. This is also true in the case of homosexual men.

Mycobacterium tuberculosis (TB) can manifest also as epididymitis. "Beadlike" irregularities along vas deferens are the characteristic sign of this condition. Other bacteria (such as Ureaplasma) may also cause epididymitis.

A non-infectious cause of epididymitis is the use of anti-arrhythmic medication, amiodarone. In this case, the inflammation is limited to the head of the epididymis and does not respond to anti-microbial therapy. The treatment is dosage reduction or change of medications.

An increased risk is associated with sexually-active men who are not monogamous and do not use condoms. Men who have recently had surgery or have a history of structural problems involving the genito-urinary tract are also at increased risk (regardless of sexual behaviors). Other risk factors include chronic indwelling urethral catheter use and being uncircumcised.

Epididymitis may begin with a low grade fever and chills and a heavy sensation in the testicle. The testicle becomes increasingly sensitive to pressure or traction.

There may be lower abdominal discomfort or pelvic discomfort, and urination may cause burning or pain. On occasion, there may be a discharge from the urethra, blood in the semen, or pain on ejaculation. The testicle may enlarge significantly and produce severe pain.

It is important that this condition be distinguished from testicular torsion (a reduction or stoppage of the blood flow to the testicle) which requires emergency care. Testicular torsion is a surgical emergency and should be treated as soon as possible. Acute testicular pain should never be ignored.

• Painful scrotal swelling (testes enlarged)
• Testicular lump
• Tender, swollen testicle on affected side
• Tender, swollen groin area on affected side
• Testicle pain aggravated by bowel movement
• Fever
• Discharge from urethra (the opening at the end of the penis)
• Blood in the semen
• Groin pain

Physical examination shows a red, tender, and sometimes swollen mass on the affected hemi-scrotum. Tenderness is usually localized to a small area of the testicle where the epididymitis is attached.

Enlarged lymph nodes in the groin area (inguinal nodes) may be present. There may be a discharge from penis. A rectal examination may reveal an enlarged or tender prostate.

These tests may be performed:

• A urinalysis and culture (the provider may request several specimens including: initial stream, mid-stream, and after a prostate massage)
• Tests to screen for Chlamydia and gonorrhea
• CBC (complete blood count)
• Doppler ultrasound to rule out testicular torsion -- hypoechoic region may be visible on the affected side as well as increased blood flow or scrotal abscess
• Testicular scan (nuclear medicine scan) to rule out torsion -- in case of the epididymitis, increased blood flow may also be demonstrated