Overview
Acute Epididymitis
Quick Reference
Critical Alerts
- Must rule out testicular torsion: Ultrasound with Doppler if any doubt
- STI-related in young sexually active men: Chlamydia, gonorrhea
- Enteric organisms in older men or urinary abnormalities: E. coli, Pseudomonas
- Prehn's sign is unreliable: Do NOT use to rule out torsion
- Pain improves with elevation: Suggestive of epididymitis but not diagnostic
- Treat empirically after ruling out torsion: Cover likely pathogens
Key Diagnostics
| Test | Purpose |
|---|---|
| Scrotal ultrasound with Doppler | Rule out torsion (increased blood flow in epididymitis) |
| Urinalysis | Pyuria, bacteriuria |
| Urine NAAT | Chlamydia, gonorrhea |
| Urethral swab | If discharge present |
| Urine culture | Enteric organisms (older men) |
Empiric Treatment
| Population | Treatment |
|---|---|
| Sexually active <35 years (STI likely) | Ceftriaxone 500mg IM × 1 + Doxycycline 100mg BID × 10 days |
| >5 years or enteric organism likely | Levofloxacin 500mg daily × 10 days OR Ofloxacin 300mg BID × 10 days |
| MSM with history of insertive anal sex | Ceftriaxone 500mg IM × 1 + Levofloxacin 500mg daily × 10 days |
Definition
Overview
Epididymitis is inflammation of the epididymis, typically caused by bacterial infection. It is the most common cause of acute scrotum in adults. In sexually transmitted cases (younger men), Chlamydia trachomatis and Neisseria gonorrhoeae are the primary pathogens. In older men or those with urinary tract abnormalities, enteric Gram-negative organisms predominate.
Classification
By Etiology:
| Type | Age/Risk | Pathogens |
|---|---|---|
| STI-related | <35 years, sexually active | C. trachomatis, N. gonorrhoeae |
| Enteric | >5 years, BPH, instrumentation | E. coli, Pseudomonas, Enterococcus |
| MSM (insertive anal sex) | Any age | Enteric organisms ± STI pathogens |
| Chemical (reflux) | Any age | Sterile; amiodarone-associated |
Epidemiology
- Most common cause of scrotal pain in adults: 600,000 cases/year in US
- Peak age for STI-related: 19-35 years
- Peak age for enteric: >35 years
- Usually unilateral: Bilateral uncommon
Etiology
Infectious Causes:
| Age Group | Common Pathogens |
|---|---|
| <35 years, sexually active | C. trachomatis, N. gonorrhoeae |
| >5 years | E. coli, Klebsiella, Proteus, Pseudomonas |
| MSM (anal insertive) | Enteric organisms ± STI |
| Prepubertal (rare) | E. coli, often with UTI or anatomic abnormality |
Non-Infectious Causes:
- Chemical epididymitis (sterile urine reflux)
- Amiodarone-induced
- Trauma
- Behçet's disease
- Tuberculosis (chronic)
Pathophysiology
Mechanism
- Ascending infection: From urethra or bladder via vas deferens
- Colonization of epididymis: Bacterial proliferation
- Inflammation: Swelling, pain, erythema
- Extension to testis: Epididymo-orchitis if testis involved
- Complications: Abscess, chronic epididymitis, infertility (rare)
STI Transmission
- Urethral infection with C. trachomatis or N. gonorrhoeae
- Ascends via vas deferens to epididymis
- May have concurrent urethritis
Clinical Presentation
Symptoms
| Symptom | Description |
|---|---|
| Scrotal pain | Gradual onset (hours to days), unilateral |
| Swelling | Posterior/lateral testicle (epididymis) |
| Dysuria | Common with concurrent UTI or urethritis |
| Urethral discharge | STI-related cases |
| Fever | Variable |
| Inguinal pain | Referred |
Key Differentiator from Torsion:
History
Key Questions:
Physical Examination
| Finding | Significance |
|---|---|
| Tender, swollen epididymis | Posterior testicle |
| Scrotal erythema, warmth | Inflammation |
| Normal cremasteric reflex | (Absent in torsion) |
| Elevated testicle with torsion | (High-riding in torsion) |
| Prehn's sign (pain relief with elevation) | Suggestive but unreliable |
| Urethral discharge | STI-related |
| Fever | Systemic infection |
| Reactive hydrocele | May be present |
Prehn's Sign: Historically thought to differentiate epididymitis (relief with elevation) from torsion (no relief). Do NOT rely on this—Doppler ultrasound is required.
Gradual onset (torsion
sudden onset)
May have urinary symptoms (torsion
usually none)
Fever (torsion
usually none)
Older age (torsion
peak in adolescence)
Red Flags
Must Consider Testicular Torsion
| Finding | Concern | Action |
|---|---|---|
| Sudden onset severe pain | Torsion | Emergent ultrasound, urology consult |
| Adolescent/young adult | Higher risk of torsion | Low threshold for imaging |
| High-riding testicle | Torsion | Emergent ultrasound |
| Absent cremasteric reflex | Torsion | Emergent ultrasound |
| Bell-clapper deformity | Torsion | Emergent ultrasound |
Complications of Epididymitis
| Finding | Concern |
|---|---|
| Scrotal abscess | May need drainage |
| Fournier's gangrene (rare) | Surgical emergency |
| Sepsis | Systemic illness |
Differential Diagnosis
Other Causes of Acute Scrotum
| Diagnosis | Features |
|---|---|
| Testicular torsion | Sudden onset, adolescent, high-riding testis, absent Doppler flow |
| Torsion of appendix testis | Gradual onset, "blue dot sign," less severe |
| Orchitis (isolated) | Rare without epididymitis; mumps |
| Inguinal hernia | Reducible mass, bowel sounds |
| Hydrocele | Painless swelling, transilluminates |
| Scrotal abscess | Fluctuant, erythema, systemic signs |
| Trauma | History of injury |
| Tumor (testicular cancer) | Painless mass, often incidental |
Diagnostic Approach
Imaging
Scrotal Ultrasound with Color Doppler (Gold standard):
| Finding | Epididymitis | Torsion |
|---|---|---|
| Blood flow | Increased (hyperemia) | Absent or decreased |
| Epididymis | Enlarged, hypoechoic | Normal |
| Testis | Normal or orchitis (heterogeneous) | May appear ischemic |
| Hydrocele | May be present | May be present |
Laboratory Studies
| Test | Purpose |
|---|---|
| Urinalysis | Pyuria (>0 WBC/hpf), bacteriuria |
| Urine NAAT | Chlamydia, gonorrhea (first-void urine) |
| Urine culture | Enteric organisms (>5 years) |
| Urethral swab | If discharge present; Gram stain, culture, NAAT |
| CBC | WBC elevation |
Testing Algorithm
- Rule out torsion: If any doubt → Emergent ultrasound with Doppler
- Urine NAAT for CT/GC: All sexually active men
- Urine culture: Older men, recurrent, urinary abnormalities
- STI screening: HIV, syphilis if high-risk
Treatment
Principles
- Rule out testicular torsion first
- Empiric antibiotics based on likely pathogens
- Partner notification and treatment for STI cases
- Supportive care: Rest, scrotal elevation, analgesia
Empiric Antibiotic Therapy
Sexually Active Men <35 Years (STI Likely):
| Agent | Dose | Duration |
|---|---|---|
| Ceftriaxone | 500 mg IM × 1 | Single dose |
| + Doxycycline | 100 mg PO BID | 10 days |
Men >35 Years or Enteric Organism Likely:
| Agent | Dose | Duration |
|---|---|---|
| Levofloxacin | 500 mg PO daily | 10 days |
| OR Ofloxacin | 300 mg PO BID | 10 days |
MSM with Insertive Anal Sex:
| Agent | Dose | Duration |
|---|---|---|
| Ceftriaxone | 500 mg IM × 1 | Single dose |
| + Levofloxacin | 500 mg PO daily | 10 days |
Supportive Care
| Intervention | Details |
|---|---|
| Scrotal support | Jockstrap or briefs |
| Scrotal elevation | Reduce swelling |
| Ice packs | 20 min on/off, protect skin |
| NSAIDs | Ibuprofen 400-600 mg TID |
| Acetaminophen | 650-1000 mg q6h PRN |
| Rest | Avoid strenuous activity |
Partner Notification (STI Cases)
- Notify and treat all sexual partners in past 60 days
- Abstain from sex until treatment complete and symptoms resolved
- Provide resources for STI counseling
Disposition
Discharge Criteria
- Torsion ruled out
- Pain controlled
- Able to tolerate oral antibiotics
- Reliable follow-up
Admission Criteria
- Scrotal abscess requiring drainage
- Systemic illness/sepsis
- Severe pain requiring IV analgesia
- Unable to tolerate oral medications
- Suspicion for Fournier's gangrene (SURGICAL EMERGENCY)
Follow-Up
| Situation | Follow-Up |
|---|---|
| STI-related | STI clinic or PCP in 1-2 weeks; test of cure for gonorrhea |
| Enteric | Urology if recurrent or urinary abnormality |
| No improvement in 48-72 hours | Re-evaluate, consider abscess or resistant organism |
Patient Education
Condition Explanation
- "You have an infection of the tube behind the testicle called epididymitis."
- "This is usually caused by bacteria from a sexually transmitted infection or urinary infection."
- "Antibiotics will treat the infection."
Self-Care
- Elevate scrotum when resting
- Wear supportive underwear
- Apply ice packs for swelling
- Complete full course of antibiotics
STI Counseling (If Applicable)
- Notify and refer sexual partners for testing and treatment
- Abstain from sex until treatment completed and symptoms resolved
- Use condoms to prevent future STIs
- Get tested for HIV and syphilis
Warning Signs to Return
- Worsening pain despite treatment
- Fever, chills
- Spreading redness or swelling
- Unable to urinate
- Scrotal mass or abscess
Special Populations
Prepubertal Children
- Epididymitis is uncommon
- Consider anatomic abnormality (vesicoureteral reflux)
- Rule out torsion urgently
- Urology referral
Elderly
- Higher risk of enteric organisms
- May have BPH, catheter, or recent instrumentation
- Consider urology referral for recurrent episodes
HIV-Positive Patients
- Same treatment regimen
- Higher risk of atypical organisms
- Consider TB epididymitis if chronic
Amiodarone-Induced
- Chemical epididymitis (non-infectious)
- Dose-dependent
- May resolve with dose reduction
- Consider stopping amiodarone if possible
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| Doppler ultrasound if torsion considered | 100% | Rule out surgical emergency |
| Urine NAAT for CT/GC (sexually active) | >0% | Diagnose STI |
| Appropriate antibiotic based on age/risk | >5% | Guideline adherence |
| Partner notification for STI | 100% | Public health |
Documentation Requirements
- Torsion ruled out (clinical or imaging)
- STI testing ordered
- Antibiotic regimen and duration
- Partner notification plan (if STI)
- Follow-up arranged
Key Clinical Pearls
Diagnostic Pearls
- Torsion must be ruled out: Especially if sudden onset or adolescent
- Prehn's sign is unreliable: Do not use to exclude torsion
- Doppler US is definitive: Increased flow = epididymitis; absent/decreased = torsion
- STI in young, enteric in old: Guides antibiotic choice
- Urine may be normal: Especially in STI-related cases
- Check for urethral discharge: Gram stain and NAAT
Treatment Pearls
- Ceftriaxone + Doxycycline for STI: Cover both GC and CT
- Fluoroquinolone for enteric: Older men, BPH, catheters
- Supportive care helps: Elevation, ice, NSAIDs
- Complete the full course: 10 days of oral antibiotics
- Partner treatment is essential: Prevent reinfection
- Follow-up in 48-72 hours if not improving
Disposition Pearls
- Most can be discharged: With oral antibiotics
- Admit for abscess or sepsis: May need drainage
- Fournier's is a surgical emergency: Rapid debridement required
- Urology for recurrent or abnormality: Investigate underlying cause
References
- Workowski KA, et al. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1-187.
- Tracy CR, et al. Diagnosis and management of epididymitis. Urol Clin North Am. 2008;35(1):101-108.
- Trojian TH, et al. Epididymitis and orchitis: an overview. Am Fam Physician. 2009;79(7):583-587.
- McConaghy JR, et al. Evaluation of Acute Scrotal Pain. Am Fam Physician. 2022;106(2):184-190.
- Banyra O, et al. Acute epididymo-orchitis: staging and treatment. Cent European J Urol. 2012;65(3):139-143.
- Pilatz A, et al. European Association of Urology Guidelines on Urological Infections. 2023.
- Centers for Disease Control and Prevention. STI Treatment Guidelines. 2021.
- UpToDate. Acute scrotal pain in adults. 2024.