Epididymo-Orchitis
Summary
Epididymo-Orchitis is inflammation/infection of the epididymis and/or testis. It is typically caused by ascending infection. In men <35 years, it is most commonly due to sexually transmitted infections (STIs) – Chlamydia trachomatis and Neisseria gonorrhoeae. In men >35 years, enteric organisms (E. coli, Pseudomonas) are more common, often associated with UTI or BPH. Mumps can cause viral orchitis. Presentation includes unilateral scrotal pain, swelling, and tenderness, typically affecting the posterior aspect (Epididymis). Phren's sign (Pain relief on testicular elevation) is unreliable for distinguishing from torsion. Key differential is Testicular Torsion – A surgical emergency. Doppler Ultrasound shows increased blood flow (Vs. Absent in torsion). Treatment is antibiotics based on likely organism: Ceftriaxone + Doxycycline for STI; Fluoroquinolone for enteric.
Key Facts
- <35 years: STI (Chlamydia, Gonorrhoea). Sexually active.
- >35 years: Enteric organisms (E. coli). UTI, BPH, Instrumentation.
- Mumps Orchitis: Post-pubertal. Bilateral in 30%. Infertility risk.
- Key Differential: Testicular Torsion (Emergency – No blood flow on Doppler).
- Phren's Sign: Unreliable.
- Treatment: Ceftriaxone + Doxycycline (STI). Ciprofloxacin (Enteric).
Clinical Pearls
"If in Doubt, Explore": Testicular torsion is a surgical emergency. If history and Doppler are inconclusive, surgical exploration is indicated.
"Posterior = Epididymis": The epididymis lies posteriorly. Tenderness here suggests epididymitis.
"STI vs Enteric = Age/Sexual History": Young, sexually active = STI. Older, UTI symptoms = Enteric.
"Doppler Shows Increased Flow": In epididymo-orchitis. ABSENT flow = Torsion.
Why This Matters Clinically
Epididymo-orchitis is common. Distinguishing it from testicular torsion (Which requires emergency surgery) is critical.
Incidence
- Common: ~600,000 cases/year (USA).
- Age: Bimodal – Sexually active young men (<35); Older men with BPH/UTI (>35).
- Mumps Orchitis: ~30% of post-pubertal males with Mumps.
By Age and Risk Factor
| Age / Risk Factor | Organisms |
|---|---|
| <35 years (STI) | Chlamydia trachomatis (Most common). Neisseria gonorrhoeae. |
| >5 years (Enteric) | E. coli. Pseudomonas. Enterococcus. |
| Urological Instrumentation | Enteric organisms. |
| Anal Intercourse (MSM) | Enteric organisms (E. coli). Also STIs. |
| Mumps (Viral) | Paramyxovirus. Orchitis (Often without epididymitis). |
| TB | Mycobacterium tuberculosis. Chronic. "Beaded" Vas deferens. |
Pathways
| Pathway | Notes |
|---|---|
| Retrograde (Ascending) | Infection ascends from urethra via Vas deferens. Most common. |
| Haematogenous | Blood-borne (Viruses – Mumps). |
Symptoms
| Symptom | Notes |
|---|---|
| Scrotal Pain | Unilateral. Gradual onset (Over hours to days). |
| Swelling | |
| Dysuria / Urethral Discharge | If STI. |
| Fever | |
| Lower Abdominal Pain |
Signs
| Sign | Notes |
|---|---|
| Tender, Swollen Epididymis | Posterior. May become diffusely swollen. |
| Swollen Testis | If orchitis component. |
| Erythema / Warmth of Scrotum | |
| Urethral Discharge | STI. |
| Phren's Sign (Unreliable) | Pain relief on testicular elevation. Positive in Epididymitis (Theoretically). NOT reliable to exclude Torsion. |
| Cremasteric Reflex | Usually PRESENT (Vs. ABSENT in Torsion). |
| Feature | Testicular Torsion | Epididymo-Orchitis |
|---|---|---|
| Age | Typically <25 (Peak 12-18). | <35 (STI) or >5 (Enteric). |
| Onset | Sudden (<6 hours). | Gradual (Hours to Days). |
| Pain Character | Severe. Constant. | Moderate. Progressive. |
| Nausea / Vomiting | Common. | Less common. |
| Cremasteric Reflex | ABSENT. | Usually PRESENT. |
| Lie of Testis | High-riding. Horizontal lie. | Normal. |
| Doppler US | ABSENT blood flow. | INCREASED blood flow. |
| Phren's Sign | Negative (Unreliable). | Positive (Unreliable). |
| Management | Emergency Surgery. | Antibiotics. |
If ANY doubt, explore surgically.
Urinalysis / Urine Tests
| Test | Purpose |
|---|---|
| First Catch Urine (FCU) | Chlamydia / Gonorrhoea NAAT (PCR). |
| MSU (Mid-Stream Urine) | Enteric organisms. Culture. |
| Urethral Swab | If discharge present. |
Scrotal Doppler Ultrasound
| Finding | Interpretation |
|---|---|
| Increased Blood Flow | Epididymo-Orchitis. |
| ABSENT Blood Flow | Testicular Torsion (Emergency). |
| Enlarged Epididymis | Epididymitis. |
| Reactive Hydrocele | Common. |
| Abscess | Complication. |
STI Screen
- Full STI screen if STI suspected (Chlamydia, Gonorrhoea, HIV, Syphilis).
Bloods
| Test | Notes |
|---|---|
| FBC | Leucocytosis. |
| CRP | Elevated. |
| Blood Cultures | If febrile/unwell. |
Principles
- Exclude Testicular Torsion First.
- Antibiotics Based on Organism/Risk.
- Analgesia and Supportive Care.
- STI Partner Notification.
Antibiotics
STI-Related (<35 years, Sexually Active)
| Drug | Dose | Duration | Notes |
|---|---|---|---|
| Ceftriaxone | 500mg IM (Or 1g if >00kg). | Single Dose. | Covers Gonorrhoea. |
| PLUS Doxycycline | 100mg BD PO. | 14 days. | Covers Chlamydia. |
If Gonorrhoea confirmed and sensitivities known, can use Ciprofloxacin.
Enteric-Related (>35 years, UTI, Instrumentation)
| Drug | Dose | Duration | Notes |
|---|---|---|---|
| Ofloxacin | 200mg BD PO. | 14 days. | OR |
| Ciprofloxacin | 500mg BD PO. | 14 days. | Fluoroquinolone. |
| Levofloxacin | 500mg OD PO. | 14 days. | Alternative. |
Supportive Care
| Intervention | Notes |
|---|---|
| Analgesia | NSAIDs, Paracetamol. |
| Scrotal Support / Elevation | Comfort. |
| Rest | |
| Ice Packs |
Partner Notification (If STI)
- Refer to GUM (Sexual Health clinic).
- Trace and treat partners.
- Abstain from sex until both treated.
| Complication | Notes |
|---|---|
| Abscess Formation | May require drainage. |
| Chronic Epididymitis | Recurrent/Persistent pain. |
| Infertility | Mumps Orchitis (Bilateral). Obstruction. |
| Testicular Atrophy | Especially Mumps. |
| Reactive Hydrocele | Usually resolves. |
| Sepsis | Rare if treated. |
| Scenario | Outcome |
|---|---|
| Treated Appropriately | Full recovery. |
| Mumps Orchitis | ~30-50% develop some degree of testicular atrophy. Infertility if bilateral. |
| Chronic Epididymitis | May cause persistent pain/discomfort. |
Key Guidelines
| Guideline | Organisation | Notes |
|---|---|---|
| BASHH Guidelines (Epididymo-Orchitis) | British Association for Sexual Health and HIV | UK STI management. |
| EAU Guidelines (Urological Infections) | European Association of Urology | Enteric causes. |
Scenario 1:
- Stem: A 22-year-old sexually active man presents with gradual onset left scrotal pain and swelling over 2 days. He has dysuria and urethral discharge. What is the likely diagnosis and treatment?
- Answer: Epididymo-Orchitis (STI – Chlamydia/Gonorrhoea). Treat with Ceftriaxone 500mg IM stat + Doxycycline 100mg BD for 14 days.
Scenario 2:
- Stem: How do you distinguish Epididymo-Orchitis from Testicular Torsion on Doppler Ultrasound?
- Answer: Epididymo-Orchitis = Increased blood flow. Torsion = Absent blood flow.
Scenario 3:
- Stem: What antibiotics are used for Enteric epididymo-orchitis in a 60-year-old man with BPH?
- Answer: Ciprofloxacin 500mg BD PO for 14 days (Or Ofloxacin).
| Scenario | Urgency | Action |
|---|---|---|
| Sudden onset pain, Suspected Torsion | Emergency | A&E. Urology. Surgical exploration. |
| Typical Epididymo-Orchitis | Routine | GP/GUM treatment. |
| Abscess / Failing to Improve | Urgent | Urology. Consider drainage. |
| STI Confirmed | Urgent | GUM for partner notification. |
What is Epididymo-Orchitis?
Epididymo-Orchitis is an infection of the tubes at the back of the testicle (epididymis) and sometimes the testicle itself. It causes pain and swelling in the scrotum.
What causes it?
- In younger men: Usually sexually transmitted infections (Chlamydia, Gonorrhoea).
- In older men: Usually urinary tract infections.
- Mumps virus can also cause it.
How is it treated?
- Antibiotics (A course of tablets or an injection).
- Painkillers.
- Supportive underwear.
Key Counselling Points (If STI)
- Complete Antibiotics: "Finish the full course."
- Partners: "Your partner(s) need testing and treatment."
- Abstain from Sex: "Until you and your partner are treated."
| Standard | Target |
|---|---|
| Doppler USS performed if torsion not excluded | 100% |
| STI screen offered to <35 years | 100% |
| Partner notification for STI cases | 100% |
- Phren's Sign: Described by Phren (1877). Historically used but now known to be unreliable.
- Doppler Ultrasound: Gold standard for distinguishing torsion from epididymitis since 1980s.
- BASHH Guidelines. Epididymo-Orchitis. bashh.org
- EAU Guidelines. Urological Infections. uroweb.org
Last Reviewed: 2025-12-24 | MedVellum Editorial Team
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. If you have scrotal pain, seek medical attention – Testicular torsion is an emergency.