Table of Contents
Overview – Epididymo-Orchitis
Epididymo-orchitis is the inflammation of the epididymis and testis, typically caused by infection and presenting as unilateral testicular pain with swelling. It is most common in sexually active men and adolescents, but can also occur in children due to viral causes. Prompt diagnosis is crucial to exclude testicular torsion and initiate antibiotic treatment.
Definition
Epididymo-orchitis refers to inflammation of both the epididymis and testis, usually due to ascending bacterial or viral infection.
Aetiology
- Sexually transmitted infections (STIs) (most common in sexually active males):
- Chlamydia trachomatis (~50%)
- Neisseria gonorrhoeae
- Non-STI causes:
- Escherichia coli and other uropathogens in older men with urinary tract abnormalities
- Children:
- Viral infection – Mumps virus (especially with parotitis)
Pathogenesis
- Infection ascends via the urethra and vas deferens, or spreads haematogenously, leading to inflammation of the epididymis and testis.
- Inflammatory response → local oedema, pain, and systemic symptoms such as fever.
Morphology
Macroscopic:
- Swollen, erythematous scrotum
- Hot, tender testis
- May mimic testicular torsion in acute setting
Microscopic:
- Neutrophilic infiltration
- Oedema and occasional testicular necrosis
Clinical Features
Symptoms:
- Gradual onset of severe, unilateral testicular pain
- Pain may radiate to the inguinal region
- Scrotal erythema and oedema
- Dysuria, urethral discharge, or symptoms of urethritis
- Fever and malaise
Investigations
- Doppler ultrasound – to assess blood flow and exclude torsion, which is a surgical emergency
- Urinalysis and urine MCS – identify bacterial pathogens
- NAATs (PCR or ELISA) – for Chlamydia and Gonorrhoea
- Full blood count (FBC) – may show raised WCC
- Urethral swabs (if discharge present)
Management
- Empirical antibiotics:
- Ceftriaxone + Doxycycline (for STI-related causes)
- Ciprofloxacin (for urinary pathogens in older men)
- Analgesia – NSAIDs
- Scrotal elevation and rest
- Follow-up to ensure resolution and STI contact tracing if applicable
Summary – Epididymo-Orchitis
Epididymo-orchitis is a common cause of unilateral testicular pain in men, often due to Chlamydia or Gonorrhoea, or viral infections such as mumps in children. Prompt assessment and treatment with antibiotics are essential to prevent complications and rule out testicular torsion. For a broader context, see our Reproductive Health Overview page.