Epididymitis is inflammation of the epididymis. Orchitis is inflammation of the testicle. Epididymo-orchitis is usually the result of infection in the epididymis and testicle on one side.
At the back of each testicle is the epididymis. Sperm are released from the testicle, into the head of the epididymis, connected at the top of the testicle. The sperm travel through the head, then body, then tail of the epididymis. Sperm mature and are stored in the epididymis. The epididymis drains into the vas deferens.
- Escherichia coli (E. coli)
- Chlamydia trachomatis
- Neisseria gonorrhoea
TOM TIP: Think of mumps in patients with parotid gland swelling and orchitis. Mumps tends only to affect the testicle, sparing the epididymis. It can also cause pancreatitis.
Epididymo-orchitis typically presents with a gradual onset, over minutes to hours, with unilateral:
- Testicular pain
- Dragging or heavy sensation
- Swelling of testicle and epididymis
- Tenderness on palpation, particularly over epididymis
- Urethral discharge (should make you think of chlamydia or gonorrhoea)
- Systemic symptoms such as fever and potentially sepsis
The key differential diagnosis for epididymo-orchitis is testicular torsion. Testicular torsion is a urological emergency that requires rapid treatment to avoid the testicle dying. Both present similarly, with acute onset of pain in one testicle. If there is any doubt, treat it as testicular torsion until proven otherwise.
The key with epididymo-orchitis is to distinguish whether the cause is likely to be an enteric organism (e.g., E. coli) or a sexually transmitted organism (e.g., chlamydia or gonorrhoea). The features that make a sexually transmitted organism more likely are (as per NICE CKS 2020):
- Age under 35
- Increased number of sexual partners in the last 12 months
- Discharge from the urethra
Investigations to help establish the diagnosis are:
- Urine microscopy, culture and sensitivity (MC&S)
- Chlamydia and gonorrhoea NAAT testing on a first pass urine
- Charcoal swab of purulent urethral discharge for gonorrhoea culture and sensitivities
- Saliva swap for PCR testing for mumps, if suspected
- Serum antibodies for mumps, if suspected (IgM – acute infection, IgG – previous infection or vaccination)
- Ultrasound may be used to assess for torsion or tumours
Acutely very unwell or septic patients are admitted to hospital for treatment (IV antibiotics).
Patients with a high risk of sexually transmitted infection should be referred urgently to genitourinary medicine (GUM) for assessment and treatment.
Local guidelines guide the choice of antibiotic.
For patients that are at a low risk of STIs, a typical choice is:
- Ofloxacin (usually first-line) for 14 days
- Levofloxacin / ciprofloxacin
- Supportive underwear
- Reduce physical activity
- Abstain from intercourse
TOM TIP: Quinolone antibiotics such as ofloxacin, levofloxacin and ciprofloxacin are powerful broad-spectrum antibiotics, often used for urinary tract infections, pyelonephritis, epididymo-orchitis and prostatitis. They give excellent gram-negative cover. It is worth remembering two critical side effects, as these may be tested in exams and are essential to inform patients about:
- Tendon damage and tendon rupture, notably in the Achilles tendon
- Lower seizure threshold (caution in patients with epilepsy)
Epididymo-orchitis can lead to:
- Chronic pain
- Chronic epididymitis
- Testicular atrophy
- Sub-fertility or infertility
- Scrotal abscess
Last updated May 2021