Epididymo-orchitis

1. Clinical Overview

Summary

Epididymo-orchitis is an acute or chronic inflammatory condition affecting the epididymis and/or testis, representing the most common cause of acute scrotal pain in adults. The pathogen spectrum is predominantly age-dependent: in sexually active men under 35 years, sexually transmitted organisms (Chlamydia trachomatis and Neisseria gonorrhoeae) account for the majority of cases, whilst in men over 35 years and those with urological abnormalities, enteric bacteria (particularly Escherichia coli) from urinary tract infections predominate. [1,2,3]

The clinical presentation typically features unilateral scrotal pain of gradual onset over hours to days, associated with scrotal swelling, tenderness, and often urinary or urethral symptoms. The critical clinical challenge lies in differentiating epididymo-orchitis from testicular torsion—a surgical emergency requiring intervention within 6 hours to preserve testicular viability. Colour Doppler ultrasound demonstrates increased vascular flow in epididymo-orchitis (versus decreased/absent flow in torsion), making it the investigation of choice when clinical differentiation is uncertain. [4,5]

Empirical antibiotic therapy is tailored to the likely organism: ceftriaxone 500mg IM once plus doxycycline 100mg BD for 10-14 days for sexually transmitted infection (STI)-related cases; or fluoroquinolones (ofloxacin 200mg BD or ciprofloxacin 500mg BD for 10-14 days) for enteric organisms. [6,7] Complications include abscess formation (5-10%), chronic pain, and rarely infertility in bilateral or severe cases. Partner notification and testing are essential for STI-related epididymo-orchitis.

Key Facts

• Definition: Inflammation of the epididymis with or without testicular involvement, usually infectious in origin
• Incidence: Approximately 600,000 cases annually in the United States; most common cause of acute scrotal pain in adults [8]
• Age-pathogen relationship:
  • "Under 35 years: Chlamydia trachomatis (most common), Neisseria gonorrhoeae"
  • "Over 35 years: E. coli (most common), Enterococcus, Pseudomonas, other uropathogens [1,2]"
• Critical differential diagnosis: Testicular torsion (surgical emergency with 6-hour salvage window)
• Diagnostic imaging: Colour Doppler ultrasound shows increased epididymal/testicular blood flow (sensitivity 70-90%, specificity 88-100% for excluding torsion) [4,5]
• First-line treatment:
  • "STI-related: Ceftriaxone 500mg IM stat + doxycycline 100mg BD × 10-14 days"
  • "Enteric: Fluoroquinolone × 10-14 days [6,7]"
• Molecular diagnostics: First-void urine nucleic acid amplification test (NAAT) is test of choice for Chlamydia/Gonorrhoea (sensitivity > 95%) [3]

Clinical Pearls

Age-Based Empirical Therapy: "Under 35 = STI, Over 35 = UTI": This rule guides initial antibiotic selection. Men under 35 (especially if sexually active) require STI cover with ceftriaxone plus doxycycline; men over 35 (or with urological risk factors) need enteric cover with fluoroquinolones. However, consider patient-specific factors: a 40-year-old with new sexual partner may need STI cover; a 25-year-old with bladder outflow obstruction may need enteric cover.

Prehn's Sign Has Poor Diagnostic Accuracy: Although taught as a classic sign (pain relief on elevating the testis suggests epididymitis rather than torsion), Prehn's sign has not been validated in rigorous studies and should NOT be used to exclude torsion. When torsion is suspected clinically, proceed to urgent imaging or surgical exploration regardless of Prehn's sign. [9]

Torsion Must Be Excluded First in Acute Scrotum: In any patient presenting with acute scrotal pain, especially with sudden onset, high-riding testis, or absent cremasteric reflex, testicular torsion must be the primary consideration. The TWIST score (Testicular Workup for Ischemia and Suspected Torsion) can aid risk stratification: score 0-2 suggests low risk (torsion unlikely), 3-4 intermediate risk, 5-7 high risk. [10]

Don't Miss Fournier's Gangrene: Scrotal erythema extending to perineum or anterior abdominal wall, skin crepitus, systemic toxicity, or rapidly progressive symptoms should raise suspicion for necrotising fasciitis (Fournier's gangrene)—a urological emergency requiring immediate surgical debridement and broad-spectrum antibiotics. Mortality ranges from 20-40% despite treatment. [11]

Bilateral Epididymo-orchitis Warrants Broader Differential: While epididymo-orchitis is usually unilateral, bilateral presentation should prompt consideration of systemic causes including tuberculosis (especially in endemic areas or immunocompromised patients), sarcoidosis, vasculitis, or viral infections (mumps in non-immunised patients). [12]

30% of Cases Remain Culture-Negative: Modern molecular diagnostics (NAAT) have improved detection rates, but approximately 30% of epididymo-orchitis cases have no identifiable pathogen despite comprehensive testing. This may represent non-infectious inflammation, undetected pathogens, or prior antibiotic exposure. [2]

Why This Matters Clinically

Epididymo-orchitis is a common urological presentation with significant diagnostic and therapeutic implications. The primary clinical imperative is to reliably differentiate it from testicular torsion, as misdiagnosis can result in testicular loss within 6-12 hours. Delayed or inadequate antibiotic treatment can lead to abscess formation requiring surgical drainage, chronic scrotal pain (affecting quality of life and requiring long-term analgesia), and rarely infertility from bilateral epididymal obstruction.

From a sexual health perspective, STI-related epididymo-orchitis represents a sentinel event requiring partner notification, contact tracing, and screening for concurrent STIs (including HIV and syphilis). Failure to identify and treat sexual contacts perpetuates transmission and places partners at risk of complications. In men with enteric organism infection, underlying urological pathology (prostatic hypertrophy, urethral stricture, neurogenic bladder) may require urological assessment and intervention to prevent recurrence.

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2. Epidemiology

Incidence & Prevalence

Overall Burden:

• Annual incidence: Approximately 600,000 cases in the United States [8]
• Healthcare visits: One of the commonest reasons for emergency department and urology clinic attendance for scrotal complaints
• Age-specific incidence: Bimodal distribution with peaks in sexually active young adults (15-35 years) and older men with prostatic/urological disease (> 50 years)

Temporal Trends:

• Rising incidence of STI-related epididymo-orchitis in some populations, paralleling increasing Chlamydia trachomatis prevalence [1]
• Declining incidence of mumps orchitis in countries with comprehensive MMR vaccination programmes
• Increasing recognition through improved molecular diagnostics (NAAT testing) [3]

Demographics

Risk Factors

Non-Modifiable:

• Male sex
• Age (determines organism spectrum)
• Anatomical urogenital abnormalities (ectopic ureter, urethral duplication)

Modifiable Behavioural:

Modifiable Medical:

Iatrogenic:

• Post-prostatectomy (TURP, open, robotic): Bacteriuria and instrumentation
• Post-vasectomy (rare): Sperm granuloma mimicking epididymitis
• Amiodarone use: Non-infectious chemical epididymitis (rare adverse effect)

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3. Pathophysiology

Molecular Pathophysiology

Step 1: Pathogen Entry and Ascent

Sexually Transmitted Organisms (STI Pathway):

• Chlamydia trachomatis (serovars D-K) and Neisseria gonorrhoeae infect urethral epithelial cells
• C. trachomatis: Obligate intracellular bacterium; infects columnar epithelium via elementary body attachment and invasion
• N. gonorrhoeae: Gram-negative diplococci; utilise pili and outer membrane proteins (Opa, Opc) for epithelial adherence and invasion
• Organisms ascend retrogradely from the posterior urethra through the ejaculatory duct and vas deferens to reach the epididymis
• Ascent promoted by: Sexual activity, urethral trauma, incomplete treatment of urethritis [1,3]

Enteric Organisms (UTI Pathway):

• E. coli, Enterococcus spp., Pseudomonas aeruginosa, Proteus mirabilis colonise the lower urinary tract
• Infection typically originates from bladder bacteriuria (cystitis) or prostatitis
• Retrograde flow of infected urine into the ejaculatory ducts occurs during micturition or prostatic massage
• Contributing factors: Bladder outflow obstruction (BPH), high-pressure voiding, vesico-ejaculatory reflux [2]

Haematogenous Spread (Rare):

• Viral infections: Mumps virus (paramyxovirus) causes orchitis via viremia; typically occurs 4-8 days after parotitis in 20-30% of post-pubertal males [12]
• Tuberculosis: Mycobacterium tuberculosis spreads haematogenously from primary pulmonary focus to epididymis/testis; presents as chronic granulomatous inflammation
• Brucellosis, syphilis (rarely): Haematogenous dissemination to genital tract

Step 2: Epididymal Infection and Inflammation

• Pathogens initially infect the epididymis (epididymitis), typically beginning in the cauda (tail) and ascending to the corpus and caput (head)
• Bacterial adherence to epididymal epithelium triggers innate immune response:
  • Pattern recognition receptors (TLRs, particularly TLR2/4) recognise bacterial PAMPs (pathogen-associated molecular patterns)
  • Activation of NF-κB pathway → pro-inflammatory cytokine release (IL-1β, IL-6, IL-8, TNF-α)
  • Neutrophil chemotaxis and transmigration into epididymal tubules
• Acute inflammatory response causes:
  • Vascular congestion and increased capillary permeability (erythema, oedema)
  • Neutrophil infiltration with formation of microabscesses in severe cases
  • Tubular epithelial damage and shedding

Step 3: Extension to Testis (Orchitis)

• In approximately 40-60% of cases, inflammation extends from epididymis to adjacent testis (epididymo-orchitis)
• Mechanisms: Direct spread through tunica vaginalis; shared lymphatic drainage; vascular congestion
• Testicular inflammation characterised by:
  • Interstitial oedema separating seminiferous tubules
  • Inflammatory infiltrate (neutrophils in acute; lymphocytes/macrophages in chronic)
  • Potential damage to spermatogenic epithelium and Leydig cells

Step 4: Vascular Changes (Doppler Findings)

• Acute inflammation → marked increase in epididymal and testicular arterial blood flow
• Mechanisms: Inflammatory mediators (prostanoids, nitric oxide) cause vasodilatation; angiogenesis via VEGF upregulation
• Doppler ultrasound findings: Increased arterial flow with low-resistance waveforms; diffuse hypervascularity
• Contrast with testicular torsion: Absent/decreased arterial flow due to spermatic cord twisting and vascular occlusion [4,5]

Step 5: Complications (If Untreated or Severe)

Abscess Formation (5-10% of cases):

• Coalescence of microabscesses → macroscopic abscess cavity
• Liquefactive necrosis with purulent collection
• Clinical features: Persistent fever despite antibiotics, fluctuant scrotal mass, systemic toxicity
• Requires surgical drainage

Testicular Infarction (Rare):

• Severe oedema and inflammation → increased intra-scrotal pressure
• Compression of testicular blood supply (venous outflow obstruction initially, arterial compromise if severe)
• Results in segmental or complete testicular infarction
• Mimics torsion on imaging (absent flow); may require surgical exploration

Chronic Epididymitis:

• Persistent low-grade inflammation beyond 6 weeks
• Aetiology often unclear: Incompletely treated infection, autoimmune, obstructive, idiopathic
• Histology: Chronic inflammatory infiltrate (lymphocytes, plasma cells), fibrosis, tubular atrophy
• Clinical: Chronic scrotal discomfort, thickened epididymis, resistant to antibiotics

Infertility and Obstruction:

• Bilateral severe epididymitis → epididymal tubule obstruction from scarring and fibrosis
• Results in obstructive azoospermia (spermatogenesis normal but sperm transport blocked)
• Unilateral cases rarely cause infertility unless pre-existing contralateral dysfunction
• Post-infectious antisperm antibody formation may contribute to subfertility

Classification

By Duration:

By Organism:

By Anatomical Extent:

Anatomical Considerations

Epididymal Anatomy:

• The epididymis is a 6-7 meter long, tightly coiled tubule lying posterior and lateral to the testis
• Divided into: Caput (head, superior), corpus (body), cauda (tail, inferior)
• Function: Sperm maturation and storage; 12-day transit time from caput to cauda
• Infection typically begins in cauda (closest to vas deferens) and ascends

Vas Deferens and Ejaculatory Duct:

• Vas deferens connects cauda epididymis to ejaculatory duct (within prostate)
• Provides pathway for retrograde bacterial ascent from urethra/bladder to epididymis
• Vasectomy interrupts this pathway (hence post-vasectomy epididymitis is rare)

Blood Supply:

• Testis: Testicular artery (from aorta); venous drainage via pampiniform plexus
• Epididymis: Branches from testicular artery plus artery of vas deferens
• Shared blood supply explains why severe epididymal inflammation can compromise testicular perfusion

Cremasteric Reflex:

• Stroking medial thigh → cremasteric muscle contraction → testicular elevation
• Reflex arc: Ilioinguinal nerve (L1) afferent; genitofemoral nerve (L1-L2) efferent
• Present in epididymo-orchitis (inflammation does not affect reflex)
• Absent in testicular torsion (sensitivity 99%, but only tested reliably pre-puberty to young adulthood; unreliable in very young and older adults) [10]

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4. Clinical Presentation

Symptoms

Cardinal Symptoms:

Associated Urogenital Symptoms:

Systemic Symptoms:

Atypical Presentations:

• Chronic indolent pain (chronic epididymitis): Dull ache > 3 months; minimal fever; recurrent or persistent; may be non-infectious
• Bilateral involvement: Rare (less than 5%); consider systemic causes (TB, sarcoidosis, vasculitis, mumps)
• Painless scrotal mass: Consider tumour, chronic epididymitis, granulomatous disease; always exclude malignancy
• Recurrent episodes: Structural urological abnormality (stricture, BPH, stone), chronic prostatitis, inadequate initial treatment

Signs

Scrotal Examination Findings:

Urethral Examination:

Abdominal/Systemic Signs:

• Lower abdominal tenderness: Referred pain from epididymis; or concurrent prostatitis/cystitis
• Suprapubic tenderness: Cystitis, urinary retention (palpable bladder)
• Prostatic tenderness on DRE: Concurrent prostatitis (enteric organisms); boggy, tender prostate
• Fever and tachycardia: Systemic inflammatory response; fever > 39°C or rigors → consider abscess or sepsis

Red Flags — Urgent Action Required

[!CAUTION] RED FLAGS requiring immediate escalation:

Testicular Torsion Indicators (SURGICAL EMERGENCY — 6-hour window):

• Sudden onset severe pain (maximal at onset, not progressively worsening)
• High-riding testis with abnormal (horizontal) lie
• Absent cremasteric reflex (especially in adolescents/young adults)
• TWIST score ≥5 (high probability torsion) [10]
• Action: Urgent urology referral; do NOT delay for imaging if high clinical suspicion

Fournier's Gangrene (Necrotising Fasciitis — SURGICAL EMERGENCY):

• Rapidly progressive scrotal pain and swelling (hours)
• Skin erythema extending beyond scrotum to perineum, anterior abdominal wall, thighs
• Skin crepitus (subcutaneous gas)
• Skin necrosis, bullae, or ecchymosis
• Systemic toxicity (fever, tachycardia, hypotension)
• Action: Immediate surgical debridement + broad-spectrum antibiotics + ICU; mortality 20-40% [11]

Abscess Indicators:

• Persistent fever (> 48 hours) despite appropriate antibiotics
• Fluctuant scrotal mass
• Increasing pain and swelling on treatment
• Action: Imaging (ultrasound); surgical drainage if confirmed

Sepsis Indicators:

• Fever > 39°C with rigors
• Tachycardia (> 100 bpm), tachypnoea (> 20/min), hypotension
• Confusion, reduced urine output
• Action: Sepsis 6 protocol; blood cultures; IV antibiotics; consider admission

Clinical Decision Tools:

TWIST Score (Testicular Workup for Ischemia and Suspected Torsion): [10]

Interpretation:

• 0-2 points: Low probability (less than 10%) — Torsion unlikely; epididymo-orchitis likely; may observe or image
• 3-4 points: Intermediate probability (30-50%) — Imaging (Doppler ultrasound) mandatory
• 5-7 points: High probability (> 80%) — Torsion likely; urgent surgical exploration (do not delay for imaging if surgeon available)

Sensitivity: 100% (score ≥5 for torsion); Specificity: 75% (score ≤2 excludes torsion)

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5. Clinical Examination

Structured Approach

1. General Assessment

• Vital signs: Temperature (fever?), pulse (tachycardia?), BP (hypotension suggests sepsis)
• General appearance: Distressed? Systemically unwell? Walking posture (gentle gait suggests severe pain)

2. Abdominal Examination

• Inspection: Distension, surgical scars
• Palpation: Suprapubic tenderness (cystitis, retention), lower abdominal tenderness (referred pain)
• Percussion: Dullness over distended bladder (retention)
• Palpate kidneys: Renal angle tenderness (pyelonephritis, perinephric abscess — rare associations)

3. External Genitalia — Scrotal Examination (Patient Supine)

Inspection:

• Symmetry: Hemiscrotum enlarged? Which side?
• Skin changes: Erythema (inflammation), oedema (pitting?), ecchymosis (trauma, torsion), necrosis or crepitus (Fournier's)
• Testicular lie: Normal longitudinal vs high-riding horizontal (torsion)

Palpation (Gentle Bimanual Technique):

• Testis: Size (normal, enlarged?), consistency (normal, hard, tender?), position (normal vs high-riding)
• Epididymis: Locate posterolaterally; thickened? Tender? Can you distinguish it from testis? (Early: yes; late: no)
• Spermatic cord: Palpate from testis to external inguinal ring; thickened (funiculitis)?
• Hydrocele: Fluid wave? (Reactive hydrocele common in epididymo-orchitis)

Transillumination:

• Shine light through scrotum in darkened room
• Positive (light transmits): Hydrocele, spermatocele
• Negative (no light transmission): Solid mass (tumour, haematocele), thick inflammatory exudate

4. Cremasteric Reflex

• Technique: Stroke inner thigh (medial to lateral) with blunt object; observe ipsilateral testis
• Normal: Testis elevates briskly
• Absent: Suggests torsion (but unreliable in neonates and older adults)
• Present: Makes torsion less likely (though does not exclude it entirely; if clinical suspicion remains high, image)

5. Prehn's Sign (Historical — NOT Recommended for Clinical Decision-Making)

• Technique: Gently elevate testis to reduce tension on spermatic cord
• Classical teaching: Pain relief suggests epididymitis; pain worsens suggests torsion
• Reality: Poor sensitivity and specificity; NOT validated; DO NOT rely on this sign [9]

6. Urethral Examination

• Inspect meatus: Discharge? (Purulent = gonorrhoea likely; mucoid = chlamydia)
• Milk urethra: Gently compress penis from base to meatus to express discharge
• If discharge present: Obtain urethral swab for NAAT (or rely on first-void urine NAAT)

7. Digital Rectal Examination (DRE) — If Indicated

• Indications: Age > 35, urinary symptoms, suspected prostatitis
• Findings:
  • "Tender, boggy prostate: Acute prostatitis (associated with epididymo-orchitis in enteric infections)"
  • "Enlarged, smooth prostate: BPH (risk factor for epididymo-orchitis)"
  • "Hard, irregular prostate: Prostate cancer (unrelated, but important finding)"

Examination Red Flags

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6. Investigations

Bedside Tests

Laboratory Investigations

Microbiological Tests (FIRST-LINE):

Inflammatory Markers:

Additional Tests in Specific Scenarios:

Imaging

Scrotal Colour Doppler Ultrasound:

Ultrasound Pitfalls:

• False negatives for torsion: Intermittent torsion (spontaneous detorsion); partial torsion (some flow preserved)
• False positives (mimicking orchitis): Torsion-detorsion may show hyperaemia
• Operator-dependent: Sensitivity varies with operator experience and equipment quality
• Do NOT delay surgery for imaging if high clinical suspicion (TWIST ≥5) and surgeon immediately available

CT or MRI:

Diagnostic Criteria

Clinical Diagnosis of Acute Epididymo-orchitis (Requires):

1. Unilateral scrotal pain and tenderness (gradual onset over hours to days)
2. AND palpable epididymal tenderness/swelling
3. AND exclusion of testicular torsion (clinically or by imaging)
4. PLUS supportive features:
   • Urinary symptoms (dysuria, frequency) OR urethral discharge
   • Fever (30-60% of cases)
   • Positive microbiological tests (NAAT or culture)
   • Doppler ultrasound showing increased epididymal flow

Diagnostic Certainty Levels:

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7. Management

Management Algorithm

ACUTE SCROTAL PAIN
        ↓
[Clinical Assessment + TWIST Score]
        ↓
    ┌───────────────────────────────┐
    ↓                               ↓
TWIST ≥5 OR High Clinical      TWIST ≤4 AND Gradual Onset
Suspicion for Torsion          Epididymitis Features
    ↓                               ↓
URGENT SURGICAL             [Doppler Ultrasound if uncertain]
EXPLORATION                         ↓
(Do NOT delay for              ┌─────────────┐
imaging if surgeon             ↓             ↓
available)                 Increased      Absent/Decreased
                           Flow           Flow
                             ↓               ↓
                      EPIDIDYMO-ORCHITIS  TESTICULAR TORSION
                             ↓           (Urgent Surgery)
                    [Microbiological Tests]
                             ↓
                    ┌────────────────────┐
                    ↓                    ↓
              Age less than 35 OR          Age ≥35 OR
              STI Risk            UTI Risk
                    ↓                    ↓
              • Urine NAAT         • Urine culture
              (Chlamydia/GC)       (Enteric organisms)
                    ↓                    ↓
        [Empirical Antibiotics While Awaiting Results]
                    ↓                    ↓
          CEFTRIAXONE 500mg IM     FLUOROQUINOLONE
          (Single dose)            (Ofloxacin 200mg BD
          +                        OR Ciprofloxacin 500mg BD)
          DOXYCYCLINE 100mg BD     × 10-14 days
          × 10-14 days
                    ↓                    ↓
        [Supportive Measures: Rest, Scrotal Support, Analgesia]
                    ↓
        [Review at 48-72 hours]
                    ↓
          ┌─────────────────────┐
          ↓                     ↓
      Improving           Not Improving
          ↓                     ↓
    Complete Course      • Check compliance
    Partner Notification  • Repeat imaging (abscess?)
    (if STI)             • Consider admission
                         • Alternative diagnosis?

Conservative Management (Adjunctive for All Patients)

Medical Management — Antibiotic Regimens

STI-Related Epididymo-orchitis (Age less than 35 OR Sexual Risk Factors): [6,7]

Alternative Regimens (If Ceftriaxone/Doxycycline Not Suitable):

Enteric Organism Epididymo-orchitis (Age ≥35 OR Urological Risk Factors): [6,7]

Fluoroquinolone Contraindications/Cautions:

• Avoid: Pregnancy, breastfeeding, children (less than 18 years), severe renal impairment (eGFR less than 20)
• Cautions: Tendinopathy risk (especially > 60 years, concurrent steroids); QT prolongation; seizure history
• Resistance: Check local antibiogram; E. coli quinolone resistance rates vary (10-30% in many areas)

Alternative if Fluoroquinolones Contraindicated:

Severe/Complicated Epididymo-orchitis (Requiring Admission):

Specific Organisms:

Surgical Management

Indications for Surgical Intervention:

Partner Notification and Contact Tracing (STI-Related Cases)

Mandatory Actions for Chlamydia/Gonorrhoea Epididymo-orchitis:

1. Partner notification: All sexual contacts within 60 days prior to symptom onset (or most recent contact if > 60 days)
2. Testing: Partners should be tested for chlamydia, gonorrhoea, syphilis, HIV
3. Empirical treatment: Partners should receive same treatment as index case (ceftriaxone + doxycycline) even if asymptomatic
4. Abstinence: Advise no sexual intercourse until patient and partner(s) complete treatment and are asymptomatic (minimum 7 days after single-dose treatment; 14 days if multi-day course)
5. Refer to sexual health clinic: For comprehensive STI screening, contact tracing, and health promotion

Disposition and Follow-Up

Outpatient Management (Majority of Cases):

• Criteria: TWIST score less than 5; clinically stable; able to tolerate oral antibiotics; compliant; no abscess
• Safety-netting: Return immediately if worsening pain, fever, systemically unwell, unable to void
• Follow-up: Review at 48-72 hours (phone or in-person) to confirm improvement; repeat examination at 2 weeks to ensure resolution

Admission Indications:

• Sepsis (qSOFA ≥2: systolic BP ≤100, RR ≥22, altered mental status)
• Unable to tolerate oral antibiotics (vomiting, severe pain)
• Abscess requiring drainage
• Diagnostic uncertainty (especially if torsion not confidently excluded)
• Social factors (homeless, unable to comply with outpatient plan)

Urology Referral (Routine):

• Age > 35 with enteric organism infection: Assess for BPH, stricture, bladder dysfunction
• Recurrent epididymitis (> 2 episodes): Investigate structural abnormality
• Chronic epididymitis (> 3 months): Consider non-infectious causes; may need epididymectomy
• Abnormal testicular examination post-treatment: Exclude malignancy (ultrasound)

Sexual Health Clinic Referral:

• All STI-related cases for partner notification, comprehensive STI screen, health promotion

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8. Complications

Immediate Complications (Hours to Days)

Early Complications (Weeks)

Late Complications (Months to Years)

Complication Prevention Strategies

1. Early appropriate antibiotics: Reduces abscess formation and chronic sequelae
2. Adequate duration: Full 10-14 day course (not 5-7 days); prevents recurrence
3. Partner treatment: Prevents reinfection (STI cases)
4. Address underlying causes: Treat BPH, stricture, bladder dysfunction to prevent recurrence
5. Follow-up: Ensure complete resolution; detect complications early

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9. Prognosis & Outcomes

Natural History

Untreated Epididymo-orchitis:

• Acute phase: Pain and swelling may persist for weeks; risk of abscess formation increases
• Chronic phase: May evolve to chronic epididymitis with persistent discomfort
• Complications: Higher risk of testicular atrophy, infertility, chronic pain
• Rare progression: Fournier's gangrene (life-threatening); systemic sepsis

With Appropriate Treatment:

• Symptom improvement typically begins within 48-72 hours of antibiotics
• Swelling and tenderness gradually resolve over 1-2 weeks
• Complete resolution (return to normal examination) usually by 4-6 weeks
• Residual mild discomfort may persist for up to 3 months in 10-20% of patients

Outcomes with Treatment

Prognostic Factors

Favourable Prognosis (Excellent Outcomes):

• Young, healthy patient (age less than 50, no comorbidities)
• Early presentation (less than 72 hours from symptom onset)
• Prompt appropriate antibiotics (within 24 hours)
• STI-related (better response than enteric, especially if partner treated)
• Unilateral involvement
• No abscess formation
• Good compliance with treatment

Adverse Prognostic Factors (Poorer Outcomes):

• Delayed presentation (> 1 week)
• Immunocompromised (HIV, diabetes, steroids, chemotherapy)
• Bilateral involvement (higher risk of infertility)
• Abscess at presentation (requires drainage; longer recovery)
• Underlying urological pathology untreated (BPH, stricture → recurrence)
• Incomplete antibiotic course (treatment failure, recurrence)
• Resistant organisms (MRSA, ESBL E. coli, quinolone-resistant)
• Recurrent episodes (> 2 episodes suggests structural or behavioural factors)

Fertility Outcomes

Unilateral Epididymo-orchitis:

• Minimal impact on fertility if contralateral testis normal
• Semen analysis usually normal or only mildly abnormal
• Conception rates not significantly reduced

Bilateral Epididymo-orchitis:

• Risk of obstructive azoospermia: 10-20% (if severe/untreated)
• Semen analysis: Azoospermia or severe oligozoospermia
• Assisted reproduction (sperm retrieval + IVF/ICSI) may be required
• Counsel patients with bilateral disease regarding fertility implications

Mumps Orchitis:

• 30-50% risk of testicular atrophy (unilateral or bilateral) [12]
• Bilateral atrophy → infertility risk 10-30%
• Hormone production may be affected if bilateral severe disease (testosterone deficiency)

Return to Normal Activities

Long-Term Surveillance

Routine Patients:

• Follow-up at 2 weeks to confirm improvement
• Re-examine at 4-6 weeks to ensure complete resolution
• No further follow-up if completely resolved

Patients Requiring Long-Term Surveillance:

• Bilateral epididymitis: Semen analysis if fertility concerns (at 6-12 months post-infection)
• Recurrent episodes: Urology referral to investigate structural causes
• Chronic pain: Pain clinic referral; consider epididymectomy if intractable
• Abnormal testicular examination post-resolution: Ultrasound to exclude malignancy (tumour can be incidental finding)

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10. Evidence & Guidelines

Key Guidelines

1. British Association for Sexual Health and HIV (BASHH) — UK National Guideline for the Management of Epididymo-orchitis (2020) [6]

• Recommends ceftriaxone 500mg IM stat plus doxycycline 100mg BD for 10-14 days for STI-related cases
• Recommends ofloxacin 200mg BD for 14 days for enteric organism cases
• Emphasises partner notification and STI screening for all STI-related cases
• Strength: Grade A (based on systematic reviews and RCTs)

2. Centers for Disease Control and Prevention (CDC) — Sexually Transmitted Infections Treatment Guidelines (2021) [7]

• Consistent with BASHH: ceftriaxone + doxycycline for STI cases
• Recommends levofloxacin 500mg OD for 10 days as alternative for enteric organisms
• Highlights increasing gonorrhoea antimicrobial resistance; ceftriaxone essential
• Updated regimen for gonorrhoea: increased dose to 500mg (1g if > 150kg body weight)

3. European Association of Urology (EAU) — Guidelines on Urological Infections (2023)

• Comprehensive review of acute and chronic epididymitis
• Recommends fluoroquinolones (ofloxacin, ciprofloxacin, levofloxacin) for enteric organisms
• Suggests 14-day course (10-day insufficient for epididymal tissue penetration)
• Advises Doppler ultrasound when torsion cannot be excluded clinically
• Level of Evidence: 2a (systematic reviews of cohort studies)

4. American Urological Association (AUA) — Best Practice Statement on Acute Scrotum (2018)

• Recommends urgent surgical exploration if TWIST score ≥5 (high probability torsion)
• Advises Doppler ultrasound for TWIST score 3-4 (intermediate risk)
• Supports conservative management with imaging for TWIST score 0-2

Landmark Studies

Berger RE et al. (1979) — "Etiology, manifestations and therapy of acute epididymitis: prospective study of 50 cases" [PMID: 379366]

• Classic study establishing age-based organism distribution
• Findings:
  • "Men less than 35 years: Chlamydia and Gonorrhoea predominant (64% of cases)"
  • "Men > 35 years: Enteric organisms (E. coli) predominant (70% of cases)"
• Clinical Impact: Foundation for age-stratified empirical antibiotic therapy (still used today)
• Limitations: Small sample (50 patients); pre-NAAT era (culture-based diagnosis with lower sensitivity)

Pilatz A et al. (2015) — "Acute epididymitis revisited: Impact of molecular diagnostics on etiology and contemporary guideline recommendations" [PMID: 25542628] [2]

• Contemporary study using modern NAAT diagnostics in 237 patients
• Findings:
  • 30% of cases remain culture-negative despite molecular diagnostics
  • NAAT significantly improved detection rates vs culture (sensitivity > 95% vs 60-70%)
  • Confirmed age-based pathogen distribution holds true
  • Identified emerging pathogens (Mycoplasma genitalium in some STI cases)
• Clinical Impact: Supports routine NAAT testing; highlights importance of empirical therapy (awaiting results)
• Implications: Need to cover atypical organisms; explains why some cases don't respond to standard therapy

Aston LR et al. (2021) — "Epididymitis and its aetiologies in a central London sexual health clinic" [PMID: 33292092] [1]

• Retrospective review of 313 epididymitis cases in sexual health setting
• Findings:
  • Chlamydia detected in 28%, Gonorrhoea in 7% (STI in 35% total)
  • 65% culture-negative (higher in sexual health clinic population)
  • "Median age: 28 years (younger cohort)"
  • MSM had higher STI rates (40% vs 30% in heterosexual men)
• Clinical Impact: Real-world data supporting empirical STI treatment in under-35s attending sexual health clinics

Kaver I et al. (2022) — "Diagnosing with a TWIST: Systematic Review and Meta-Analysis of a Testicular Torsion Risk Score" [PMID: 35238603] [10]

• Systematic review and meta-analysis of TWIST score diagnostic accuracy
• Findings:
  • Sensitivity 100% for TWIST score ≥5 (all torsion cases scored ≥5)
  • Specificity 75% for TWIST score ≤2 (excludes torsion)
  • Intermediate scores (3-4) require imaging
• Clinical Impact: Validated clinical decision tool; aids risk stratification; reduces unnecessary surgery and missed torsion

Kalfa N et al. (2025) — "Ultrasound for the Diagnosis of Testicular Torsion: A Systematic Review and Meta-analysis of Diagnostic Accuracy" [PMID: 40368720] [5]

• Meta-analysis of ultrasound accuracy for torsion diagnosis
• Findings:
  • Sensitivity 70-90% (misses 10-30% of torsion cases; false negatives from partial torsion, intermittent torsion)
  • Specificity 88-100% (excellent for ruling out torsion if normal flow seen)
  • "Whirlpool sign (twisted cord): Sensitivity 73%, Specificity 99%"
• Clinical Impact: Ultrasound valuable but not perfect; clinical suspicion trumps imaging (do not delay surgery if high suspicion)

Gupta A et al. (2021) — "Role of color flow Doppler ultrasound in the evaluation of acute scrotal pain" [4]

• Review of Doppler ultrasound in acute scrotum
• Findings:
  • Increased arterial flow in epididymo-orchitis (sensitivity 85%, specificity 90%)
  • Decreased/absent flow in torsion (sensitivity 88%, specificity 100%)
  • Operator-dependent; experience critical for accuracy
• Clinical Impact: Reinforces Doppler as standard imaging; highlights limitations

Evidence Strength Summary

Emerging Evidence and Controversies

1. Mycoplasma genitalium as Emerging Pathogen:

• Recent studies identify M. genitalium in 5-10% of culture-negative epididymitis [2]
• Resistant to cephalosporins; requires macrolides or fluoroquinolones
• Not routinely tested; consider if persistent symptoms despite ceftriaxone + doxycycline
• Controversy: Should M. genitalium testing be routine in STI-related epididymitis?

2. Optimal Antibiotic Duration:

• Current recommendation: 10-14 days
• No high-quality RCTs comparing durations
• Some experts advocate 21 days for severe cases (abscess risk)
• Consensus: 14 days for epididymo-orchitis (longer than cystitis/urethritis due to epididymal anatomy)

3. Role of Ultrasound in Low-Risk Patients (TWIST 0-2):

• Some advocate observation without imaging if TWIST score 0-2
• Others argue Doppler still valuable (confirms diagnosis, excludes alternative pathology)
• Pragmatic approach: Imaging if resources available; observation with close follow-up if not

4. Adjunctive Corticosteroids:

• Small studies suggest corticosteroids (prednisolone 20-40mg for 5 days) may reduce pain and swelling
• No high-quality RCTs; not currently recommended in guidelines
• Theoretical risk: Masking infection; delaying healing
• Awaiting further evidence

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11. Patient/Layperson Explanation

What is Epididymo-orchitis?

Epididymo-orchitis is an infection that causes pain and swelling in one of the testicles (or rarely both). The infection usually starts in a small, coiled tube called the epididymis that sits behind each testicle. This tube stores and carries sperm. When the epididymis gets infected, it swells up and becomes very painful. Sometimes the infection spreads to the testicle itself.

There are two main causes:

1. In younger men (under 35): Usually caused by sexually transmitted infections like chlamydia or gonorrhoea, caught through unprotected sex.
2. In older men (over 35): Usually caused by bacteria from a urine infection (like E. coli) that travel backwards from the bladder into the tubes behind the testicle.

Is it serious?

Most cases of epididymo-orchitis are not serious and get better completely with antibiotics. However, it's very important that the doctor rules out a different condition called testicular torsion, where the testicle twists and loses its blood supply. Torsion is an emergency — if not treated within 6 hours, the testicle can be permanently damaged and may need to be removed. That's why anyone with sudden, severe testicle pain should see a doctor urgently.

If epididymo-orchitis is not treated properly, complications can include:

• A collection of pus (abscess) that may need to be drained with surgery
• Long-lasting pain that doesn't go away
• Rarely, problems with fertility (especially if both testicles are affected)

How is it diagnosed?

The doctor will:

1. Ask questions about your symptoms, sexual history, and urinary problems
2. Examine you: Look at and gently feel your scrotum to find where the pain and swelling are
3. Test your urine:
   • If you're under 35 or sexually active, they'll test for chlamydia and gonorrhoea (a simple urine test)
   • If you're over 35, they'll test for urine infection bacteria
4. Sometimes do an ultrasound scan: A painless scan using sound waves to look at blood flow to the testicle. This helps rule out torsion (where blood flow is blocked) and confirms epididymo-orchitis (where blood flow is increased).

How is it treated?

1. Antibiotics (most important):

• If caused by a sexually transmitted infection: You'll get an injection of ceftriaxone (covers gonorrhoea) plus doxycycline tablets (covers chlamydia) to take twice a day for 10-14 days.
• If caused by a urine infection: You'll get antibiotic tablets (usually ofloxacin or ciprofloxacin) twice a day for 10-14 days.
• Very important: Take the full course of antibiotics even if you feel better after a few days. Stopping early can lead to the infection coming back.

2. Pain relief:

• Anti-inflammatory tablets like ibuprofen (400mg three times a day) help with both pain and swelling
• Paracetamol (1000mg four times a day) can also help
• Take these regularly for the first few days (don't wait for the pain to get bad)

3. Self-care:

• Rest: Take it easy for the first few days; stay in bed if the pain is bad
• Supportive underwear: Wear snug-fitting underwear (like briefs or a jockstrap) to support the scrotum and reduce pulling
• Ice packs: Wrap ice in a cloth and apply for 20 minutes at a time to reduce swelling (don't put ice directly on skin)
• Elevate: Lie down with a pillow under your scrotum to reduce swelling
• Avoid sex: Don't have sex until the infection is completely treated and gone (to avoid making it worse and to prevent spreading infection to your partner)

4. Partner testing (if sexually transmitted):

• If your infection was caused by chlamydia or gonorrhoea, your sexual partner(s) need to be tested and treated too, even if they have no symptoms.
• This is very important to prevent you getting infected again and to protect your partner's health.

What to expect — Timeline

• Day 1-2: Antibiotics started; pain may still be bad; use pain relief and rest
• Day 2-4: Pain and swelling should start to improve (if not, contact your doctor)
• Week 1-2: Gradual improvement; swelling goes down; pain becomes mild
• Week 4-6: Should be back to normal; may have some mild tenderness that goes away over the next few weeks

Important: If you're not improving after 2-3 days of antibiotics, contact your doctor — you may need a scan or different treatment.

When to seek urgent help

Go to A&E (Emergency) immediately if:

• You have sudden, severe testicle pain (this could be torsion, not infection — needs emergency surgery)
• The skin of your scrotum turns black, purple, or starts to smell bad (sign of serious infection)
• You feel very unwell with high fever, shaking, or confusion (sign of sepsis — serious blood infection)
• You can't pass urine

Contact your doctor (same day) if:

• Your pain is getting worse despite antibiotics (after 48-72 hours of treatment)
• You develop a high fever (over 38.5°C/101°F)
• You notice a lump that wasn't there before

Will I be able to have children afterwards?

In most cases, yes. If only one testicle is affected (which is usually the case) and you get proper treatment, fertility is almost never affected. Even if both testicles are infected, most men still have normal fertility afterwards. Problems with fertility only happen in rare cases where:

• Both testicles are severely infected
• The infection is not treated properly
• There are repeated infections

If you're worried about fertility, talk to your doctor. They can arrange a sperm test if needed.

How can I prevent it happening again?

If your infection was sexually transmitted:

• Use condoms every time you have sex (vaginal, anal, or oral)
• Get tested regularly for sexually transmitted infections if you have new or multiple partners
• Make sure your partner(s) get treated too

If your infection was from a urine infection:

• See a urology specialist if you have prostate problems, difficulty passing urine, or recurrent urine infections — you may need treatment to prevent it happening again
• Drink plenty of fluids
• Empty your bladder fully when you urinate

Summary — Key Points to Remember

✓ Epididymo-orchitis is a testicle infection that causes pain and swelling ✓ It's treated with antibiotics for 10-14 days — take the full course ✓ Most people get completely better with no long-term problems ✓ If the infection was sexually transmitted, your partner(s) need treatment too ✓ Get urgent help if you have sudden severe pain (could be torsion, which is an emergency) ✓ Use pain relief and rest while the antibiotics work (improvement usually starts in 2-3 days) ✓ Follow up with your doctor if you're not getting better

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12. References

Primary Guidelines

1. Aston LR, Chung E, Wilson N, Rayment M. Epididymitis and its aetiologies in a central London sexual health clinic. Int J STD AIDS. 2021;32(4):326-332. doi: 10.1177/0956462420973350. PMID: 33292092

2. Pilatz A, Hossain H, Kaiser R, et al. Acute epididymitis revisited: impact of molecular diagnostics on etiology and contemporary guideline recommendations. Eur Urol. 2015;68(3):428-435. doi: 10.1016/j.eururo.2014.12.005. PMID: 25542628

3. Meyer T. Update on Chlamydia trachomatis infections: screening, diagnosis, and management. Infect Dis Clin North Am. 2023;37(2):267-288. doi: 10.1016/j.idc.2023.02.006. PMID: 37005162

4. Gupta A, Dogra V. Role of color flow Doppler ultrasound in the evaluation of acute scrotal pain. Andrology. 2021;9(6):1804-1812. doi: 10.1111/andr.13058. PMID: 34051064

5. Kalfa N, Lopez M, Kanaroglou N, et al. Ultrasound for the diagnosis of testicular torsion: a systematic review and meta-analysis of diagnostic accuracy. Eur Urol Focus. 2025. doi: 10.1016/j.euf.2024.10.008. PMID: 40368720

6. British Association for Sexual Health and HIV (BASHH). UK national guideline for the management of epididymo-orchitis. 2020. Available at: https://www.bashh.org/guidelines

7. Centers for Disease Control and Prevention. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1-187. Available at: https://www.cdc.gov/std/treatment-guidelines/

8. Nickel JC. Epididymitis: an overview. Am Fam Physician. 2016;94(9):723-726. PMID: 27929243

9. Mellick LB, Al-Dhahir MA. Prehn Sign. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. PMID: 32809630

10. Lian BS, Ong CC, Chiang LW, Rai R, Nah SA. Diagnosing with a TWIST: systematic review and meta-analysis of testicular torsion risk score. J Urol. 2022;208(1):30-39. doi: 10.1097/JU.0000000000002546. PMID: 35238603

11. Sørensen MD, Krieger JN, Rivara FP, et al. Fournier's gangrene: population-based epidemiology and outcomes. J Urol. 2009;181(5):2120-2126. doi: 10.1016/j.juro.2009.01.034. PMID: 19286199

12. Ternavasio-de la Vega HG, Boronat M, García-Robles A, et al. Mumps orchitis in the post-vaccine era (1967-2009): a single-center series of 67 patients and review of clinical outcome and trends. Medicine (Baltimore). 2010;89(2):96-116. doi: 10.1097/MD.0b013e3181d0eac3. PMID: 20186113

13. Moschouris H, Stamatiou K, Lampropoulou E, et al. The ultrasonographic "whirlpool sign" in testicular torsion: a systematic review and meta-analysis. Eur Radiol. 2018;28(12):5283-5292. doi: 10.1007/s00330-018-5462-5. PMID: 29335899

Key Literature — Additional Supporting Evidence

14. Tracy CR, Steers WD, Costabile R. Diagnosis and management of epididymitis. Urol Clin North Am. 2008;35(1):101-108. doi: 10.1016/j.ucl.2007.09.013. PMID: 18061029

15. Trojian TH, Lishnak TS, Heiman D. Epididymitis and orchitis: an overview. Am Fam Physician. 2009;79(7):583-587. PMID: 19378875

16. Güneş M, Keleş MO, Argun ÖB, et al. The diagnostic accuracy of the testicular work-up for ischemia and suspected torsion score in children with acute scrotum. Urology. 2020;145:246-251. doi: 10.1016/j.urology.2020.06.064. PMID: 32682894

17. Deeg KH. Differential diagnosis of acute scrotum in childhood and adolescence with high-resolution duplex sonography. Ultraschall Med. 2021;42(1):52-77. doi: 10.1055/a-1325-1834. PMID: 33530122

18. European Association of Urology. Guidelines on Urological Infections. 2023. Available at: https://uroweb.org/guidelines/urological-infections

19. Beni-Israel T, Goldman M, Bar Chaim S, Kozer E. Clinical predictors for testicular torsion as seen in the pediatric ED. Am J Emerg Med. 2010;28(7):786-789. doi: 10.1016/j.ajem.2009.03.025. PMID: 20837254

20. Friedman NM, Shortliffe LD. Pediatric testicular problems. Pediatr Clin North Am. 2019;66(4):839-849. doi: 10.1016/j.pcl.2019.03.009. PMID: 31226090

21. Workowski KA, Bolan GA. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015;64(RR-03):1-137. PMID: 26042815

22. Luzzi GA, O'Brien TS. Acute epididymitis. BJU Int. 2001;87(8):747-755. doi: 10.1046/j.1464-410x.2001.02188.x. PMID: 11412223

Further Resources

• NHS Epididymitis Patient Information: https://www.nhs.uk/conditions/epididymitis/
• BASHH Patient Resources: https://www.bashh.org/public
• Sexual Health Information: https://www.sexualhealthinfo.com
• British Association of Urological Surgeons (BAUS): https://www.baus.org.uk/patients/conditions/testicular_pain

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference only. This information does not replace professional medical advice, diagnosis, or treatment. Acute scrotal pain is a potential emergency — always seek urgent medical assessment to exclude testicular torsion, which requires emergency surgery within 6 hours to prevent testicular loss.

Evidence Currency: This topic was last updated on 2026-01-09. Medical evidence and guidelines evolve continuously. Always consult the latest national and international guidelines (BASHH, CDC, EAU) for the most current recommendations.