Testicle pain is discomfort in one or both testicles. The pain sometimes radiates to the lower abdomen.

The testicles sit inside the scrotum. They are very sensitive. Even a minor injury can cause pain or discomfort to the testicles. Sudden, severe testicle pain, however, requires immediate medical care.

If a young man has abdominal pain, the scrotum should always be carefully examined. Abdominal pain may occur before testicle pain in some conditions, including testicular torsion. This is a twisting of the testicles that can cut off the blood supply and cause tissue to die. Testicular torsion is an emergency that needs to be treated within hours.

Testicular cancer is usually painless. But any testicle lump should be evaluated by your doctor, whether or not there is pain.

Common causes of testicle pain include:

• Injury
• Infection or inflammation
• Testicular torsion -- most common in young men between 10 and 20 years old

Possible infections include:

• Epididymitis -- inflammation of the ducts through which sperm leaves the testicle. This is often caused by chlamydia, a sexually transmitted disease, or a urinary tract infection that results from an inability to empty the bladder because of an enlarged prostate
• Orchitis -- inflammation of one or both testicles, which may be caused by bacteria or a virus like mumps. Orchitis can occur at the same time as epididymitis or prostatitis (inflammation of the prostate gland).

Fluid in the testicles often causes painless swelling, but may cause mild discomfort. There are several main types of fluid collection:

• Varicocele -- enlarged veins in the scrotum that carry blood away from the testicles.
• Spermatocele -- fluid in the epididymis that forms a cyst and often contains dead sperm cells.
• Hydrocele -- fluid in the area inside the scrotum, surrounding the testicle; common in newborns.

Pain may also be caused by a hernia or an unrelieved erection.