Last Updated: Mar 1, 2019


The epididymis is a long, tightly coiled tube located behind each testicle that connects the testicle to the ductus deferens and stores sperm.

Acute epididymitis is inflammation of the epididymis, causing pain and swelling of the scrotum. Most cases are caused by sexually transmitted bacterial infections occurring in men age 19 to 35 years old.

Chronic epididymitis refers to inflammation characterized by persistent testicular pain in the absence of scrotal swelling. This condition is usually more difficult to treat and may result in long-term pain.

Causes and Risk Factors

Side view of epididymis behind testicle

Epididymitis is usually caused by a bacterial infection that starts in the urethra, bladder, or prostate and ultimately spreads to the epididymis. Depending on the patient’s age, the most common causes of epididymitis are sexually transmitted infection, an enlarged prostate gland, or urinary tract infections.

Causal Factors

In heterosexual men under age 35, acute epididymitis is most often caused by a sexually transmitted infection with chlamydia or gonorrhea. These bacteria frequently cause serious infections of the genitals and reproductive systems of men and women. Men who practice anal intercourse may develop epididymitis caused by enteric bacteria found in the lower gastrointestinal tract, such as E. coli. Unprotected sexual intercourse or sexual intercourse with multiple partners increases the risk of these infections.

In men over age 35, the most common cause of acute epididymitis is an enlargement of the prostate gland. This condition, known as benign prostatic hypertrophy, obstructs the normal flow of urine from the bladder and causes urinary tract infections, which may later spread to the epididymis.

Less commonly, epididymitis occurs in children. In pediatric patients, epididymitis is usually related to a urinary tract infection, congenital abnormality of the genitourinary system, or the presence of foreskin on an uncircumcised penis.

Other factors increasing the risk of epididymitis include urinary tract surgeries, use of a urinary catheter for bladder drainage, or medical conditions causing suppression of the immune system, such as HIV. Uncommonly, a noninfectious type of epididymitis is the consequence of testicular trauma or use of a heart medication called amiodarone.


Major complications of acute epididymitis include chronic epididymitis, infertility, and testicular abscess. Chronic epididymitis is an outcome of inadequately treated acute epididymitis or recurrent infection. Some patients experience chronic epididymitis after vasectomy, a procedure to cut the ductus deferens as permanent birth control for men.


Patients with acute epididymitis usually complain of one-sided testicular pain, tenderness, and scrotal swelling. Other symptoms may include a cloudy discharge from the tip of the penis, frequent urination, and burning with urination.

Chronic epididymitis is distinguished by the presence of pain for longer than 6 weeks and the absence of swelling.

Diagnosis and Treatment

Male urinary tract

In acute epididymitis, the physical examination shows tenderness and swelling of the scrotum, discharge from the penis, enlarged groin lymph nodes, and fever.

Diagnostic Tests

Treatment of Acute Epididymitis

The goals are to cure the infection, prevent transmission of the infection to others, and prevent infertility or chronic pain. Treatment includes the following:

Treatment of Chronic Epididymitis

Usually, chronic epididymitis is more difficult to treat and may require 4 to 6 weeks of antibiotics. Unfortunately, some patients experience persistent pain for many years. As a last resort, doctors may consider surgery to remove the epididymis (epididymectomy).


Sexually active individuals can decrease their risk of sexually transmitted infections by using condoms for intercourse and having sex with only one partner at a time.

Anyone with urethral discharge, scrotal swelling or testicular pain should refrain from sexual activity and seek immediate medical treatment to prevent transmission of the infection to others and avoid long-term complications.


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Tina Shahian, PhD

Tina is a Life Science Writer for a number of online publications, including Innerbody.com. Her expertise is in conveying complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. In her spare time, she enjoys drawing science-related cartoons.