Epididymo-orchitis
Epididymo-orchitis is inflammation of the epididymis and/or testis, usually due to infection. Most commonly from a urinary tract infection but may also be as a result of a sexually transmitted infection.
Main differential: testicular torsion (a surgical emergency). If in doubt, assume torsion until excluded. Diagnostic tools: ultrasound, MSU, urinary PCR, and urethral swabs (if indicated).
Pathology
Organisms:
- UTI pathogens (e.g. E. coli): retrograde spread from urinary tract.
- STIs: Chlamydia trachomatis, Neisseria gonorrhoeae
- Other infective agents: mumps, TB, brucellosis, schistosomiasis, Mycoplasma pneumoniae
- Non-infectious causes: sterile urine reflux, Behçet’s disease (auto-inflammatory)
Risk Assessment
- UTI more likely in: males >35, urinary obstruction, recent instrumentation
- STI more likely in: males <35, high-risk sexual behaviour
Complications
- Abscess formation
- Reduced fertility (esp. mumps)
- Chronic inflammation
- Gangrene/sepsis (rare, esp. in diabetics or immunosuppressed)
Clinical Features
- Pain: Unilateral, gradual onset, radiates to groin/loin
- Tenderness: Often generalised scrotal; swelling, erythema
- Fever and constitutional symptoms may be present
- Urinary symptoms: frequency, dysuria (variable)
- Urethral discharge: Suggestive of STI
- Mass: Suggests abscess or tumour
Differential Diagnoses
| Epididymo-orchitis | Testicular Torsion |
|---|---|
| Gradual onset | Acute onset |
| May have fever/CRP | Afebrile/Normal CRP |
| Older age | Younger (<20 years) |
| Urinary symptoms present | Absent |
| Mild-moderate pain | Severe pain |
Other differentials: Fournier gangrene, tumour, trauma
Investigations
- Bloods: FBE, CRP (elevated in EO), U&Es, glucose, blood cultures (if septic)
- Urine: MSU for MCS
- STI tests: Urethral swab, urine PCR for Chlamydia and Gonorrhoea
- Ultrasound: with Doppler; confirms EO, excludes torsion, detects abscess, hydrocele, tumour
Management
- Analgesia: As required
- Scrotal support
- Antibiotics:
Urinary Tract Source (14 days):
- Trimethoprim 300 mg PO daily
- Cephalexin 500 mg PO BD
- Amoxicillin/clavulanate 500/125 mg PO BD
- Nitrofurantoin 100 mg PO BD
- Severe cases: IV ceftriaxone + ampicillin
Sexually Acquired (STI):
- Ceftriaxone 500 mg IM/IV single dose
- Azithromycin 1 g PO single dose PLUS:
- Doxycycline 100 mg PO BD for 14 days
- OR Azithromycin 1 g PO at Day 7 (non-adherent)
- Sexual Health Advice: Abstain from intercourse until patient and partners are treated and followed up
- Treatment failures: Consider resistant organism, urinary anomaly, mumps/TB, alternative diagnosis
Disposition
Urinary source:
- Most can be discharged with outpatient urology follow-up
- Admission for IV antibiotics if:
- Severe symptoms
- Complicated (abscess, comorbidity)
- Paediatric cases: Refer to paediatric urology
STD source:
- Ensure sexual partners are treated
- Screen for other STIs
References
FOAMed
- Rippey J. Ultrasound Case 065. LITFL
Publications
- Asgari SA, Mokhtari G, Falahatkar S, Mansour-Ghanaei M, Roshani A, Zare A, Zamani M, Khosropanah I, Salehi M. Diagnostic accuracy of C-reactive protein and erythrocyte sedimentation rate in patients with acute scrotum. Urol J. 2006 Spring;3(2):104-8.
- Street E, Joyce A, Wilson J; Clinical Effectiveness Group, British Association for Sexual Health and HIV. BASHH UK guideline for the management of epididymo-orchitis, 2010. Int J STD AIDS. 2011 Jul;22(7):361-5
Fellowship Notes
Physician in training. German translator and lover of medical history.