Epididymitis

What the epididymis does

The epididymis is a tightly coiled tube about 6 meters long when uncoiled, packed into a comma-shaped structure along the back of each testicle. Sperm made in the testicle mature there over a couple of weeks before moving into the vas deferens. When the epididymis is infected or irritated, it swells and becomes very tender. Inflammation often spreads into the testicle itself (orchitis), and the combined condition is called epididymo-orchitis.

Symptoms

• pain at the back of one testicle, spreading to the whole scrotum, groin or lower belly
• swelling, warmth and redness of the scrotum on the affected side
• a tender, thickened cord-like area behind the testicle
• burning or pain when passing urine, and needing to go often
• discharge from the penis (more common with chlamydia or gonorrhea)
• fever and feeling unwell
• sometimes pain during ejaculation or blood in the semen

How quickly do epididymitis symptoms start?

Acute epididymitis typically develops gradually over 1 to 2 days, sometimes a little longer. Pain starts as a dull ache and steadily worsens. This contrasts with testicular torsion, where severe pain comes on suddenly over minutes. Symptoms after an STI exposure usually appear within 1 to 3 weeks of the infection, though some infections are silent before spreading to the epididymis.

Epididymitis vs testicular torsion

If there is any doubt, doctors treat it as testicular torsion and arrange an urgent ultrasound or surgical exploration.

Causes

Sexually transmitted infections

In sexually active men under about 35, the commonest causes are chlamydia and gonorrhea. The bacteria travel up from the urethra. Mycoplasma genitalium is a less common cause.

Urinary bacteria

In men over 35, children and men who have insertive anal sex, enteric bacteria such as E. coli are more common. Risk factors include:

• an enlarged prostate or urethral stricture blocking urine flow
• a recent catheter, cystoscopy or prostate procedure
• urinary tract infections and prostatitis

Other causes

• Viral: mumps causes orchitis more than epididymitis, usually in unvaccinated boys and men.
• Medicine: amiodarone, a heart rhythm drug, can cause non-infectious epididymitis that settles when the dose is lowered.
• Tuberculosis and fungal infections in people with weak immune systems.
• Trauma or heavy straining, which can force urine back into the ducts.
• Inflammatory diseases such as Behcet's disease.
• In boys: often inflammation after a viral illness, or urinary tract abnormalities.

Diagnosis

1. Examination: a doctor checks the position of the testicles, feels for tenderness at the back of the testicle, and checks the cremasteric reflex.
2. Urine tests: a dipstick and culture for urinary bacteria.
3. STI testing: a urine nucleic acid amplification test (NAAT) for chlamydia and gonorrhea, plus a swab if there is discharge. HIV and syphilis testing are usually offered.
4. Scrotal ultrasound with Doppler: shows increased blood flow in epididymitis and reduced flow in torsion. It also detects an abscess.

Treatment

Treatment starts on the day of diagnosis, before test results come back.

Antibiotics

• Likely STI cause: a single injection of ceftriaxone plus a course of doxycycline, following CDC guidance.
• Likely urinary bacteria: a fluoroquinolone such as levofloxacin, chosen according to local resistance.
• Men who have insertive anal sex: cover for both.

Finish the full course even when pain improves. If an STI is the cause, sexual partners from the previous 60 days need testing and treatment, and you should avoid sex until both of you have completed treatment and symptoms have gone.

Relieving pain and swelling

• Rest, and lie with the scrotum raised on a folded towel.
• Wear supportive underwear or an athletic supporter.
• Apply ice packs wrapped in a cloth for 15 to 20 minutes at a time.
• Take ibuprofen or acetaminophen (paracetamol) at the label dose.

Pain usually improves within 1 to 3 days. Swelling and tenderness can take several weeks, sometimes up to 3 months, to settle completely.

Complications

• Abscess: a pus collection that may need drainage.
• Chronic epididymitis: pain lasting more than 6 weeks, sometimes without ongoing infection.
• Testicular atrophy: shrinking of the testicle if blood supply is affected.
• Reduced fertility: scarring can block sperm transport, especially after repeated or two-sided infections.
• Spread of infection into the bloodstream, rarely.

Prevention

• Use condoms, and get tested for STIs when you have a new partner.
• Treat urinary symptoms and prostate enlargement promptly.
• Follow catheter care advice carefully.
• Make sure boys are vaccinated against mumps (MMR).

Frequently asked questions

How quickly do epididymitis symptoms start?

Epididymitis usually develops over 1 to 2 days, beginning as a mild ache at the back of a testicle and gradually becoming more painful and swollen. Pain that comes on within minutes is more typical of testicular torsion, which is a surgical emergency.

Is epididymitis an STI?

Not always, but often. In men under 35 it is commonly caused by chlamydia or gonorrhea, which are sexually transmitted. In older men and children it is more often caused by urinary bacteria. STI testing is recommended for anyone sexually active with epididymitis.

How long does epididymitis last?

With antibiotics, pain usually improves within 72 hours. Swelling and tenderness may take several weeks to resolve fully. Pain or swelling lasting more than 6 weeks is called chronic epididymitis and needs follow-up with a urologist.

Can epididymitis go away on its own?

Bacterial epididymitis should not be left to settle by itself. Untreated infection can cause an abscess, damage the testicle and affect fertility, and an STI can spread to partners. Non-infectious forms, such as those caused by amiodarone, may settle once the cause is removed.

Does epididymitis affect fertility?

A single, promptly treated episode rarely affects fertility. Repeated infections, infections on both sides, or untreated cases can scar the epididymis and block sperm transport. If you have trouble conceiving after epididymitis, a semen analysis can check sperm count.