The epididymis is a series of small tubes, attached to the back of each testicle, that collects and stores sperm. One of the most common causes of scrotal pain is epididymitis, which is infection and subsequent inflammation of these coiled tubes. Epididymo-orchitis occurs when the infection spreads to include the testicle. Epididymitis is usually a secondary bacterial infection that is triggered by a range of conditions, such as urinary tract infections or sexually transmitted diseases. The bacteria in the urethra (the tube that allows the exit of urine and sperm from the penis) simply back-track through the urinary and reproductive structures to the epididymis. Treatment options include antibiotics and bed rest. Some men develop chronic epididymitis, which is characterised by inflammation even when there is no infection.

The symptoms of epididymitis include:

Slight fever
Chills
A sensation of heaviness in the affected testicle
The testicle becomes sensitive to touch or pressure
Enlargement of the testicle
Abdominal pain
Pelvic pain
Frequent urge to urinate
A burning sensation on urination
Discharge from the penis
Blood in the urine
Painful ejaculation.