Epididymitis

1. History

• Onset and progression: Gradual onset of unilateral posterior scrotal pain over hours to days (sudden onset raises concern for torsion) [1-2]
• Urinary symptoms: Dysuria, urinary frequency, urgency, urethral discharge [2-3]
• Sexual history: Number of partners, condom use, insertive anal intercourse, recent new partner, history of STIs [1]
• Urologic history: Recent instrumentation, catheterization, prostate biopsy, vasectomy [1]
• Associated symptoms: Fever, scrotal swelling, penile discharge, lower abdominal pain
• Important negatives: Absence of nausea/vomiting (more common in torsion), no sudden onset, no trauma [3]

2. Alarm Features

• Sudden onset of severe scrotal pain → testicular torsion until proven otherwise [1][3]
• Absent cremasteric reflex — OR 47.6 for torsion in one study; 100% of torsion patients had absent cremasteric reflex vs. only 14% of epididymitis patients [4]
• High-riding testis in transverse lie [3]
• Nausea/vomiting with acute scrotal pain [3]
• Scrotal erythema with crepitus or rapid spread → Fournier's gangrene [1]
• Fever with severe pain unresponsive to treatment → abscess, infarction, or necrotizing fasciitis [1]
• Symptoms not improving within 48–72 hours of antibiotics → reevaluate for abscess, tumor, TB, or fungal infection [1][5]

3. Medications

Empiric antibiotic regimens (CDC 2021 STI Guidelines) — start presumptively before lab results: [1][3]

• For patients ≥150 kg: use ceftriaxone 1 g IM [1][3]
• The 2024 European guideline increased the ceftriaxone dose to 1 g IM for STI-related cases and no longer recommends azithromycin dual therapy (unless cefixime is used instead of ceftriaxone) [6]
• Adjunctive care: NSAIDs, bed rest, scrotal elevation until fever and inflammation subside [1][3]
• Medication contributors: Amiodarone is a recognized non-infectious cause of epididymitis [3]
• Contraindication: Avoid fluoroquinolone monotherapy if gonorrhea has not been ruled out [1]

4. Diet

• No specific dietary triggers or restrictions
• Adequate hydration is recommended, particularly if concurrent UTI is present
• Avoid alcohol during antibiotic therapy (general guidance)

5. Review of Systems

• GU: Dysuria, frequency, urgency, urethral discharge, hematuria
• Constitutional: Fever, chills, malaise
• GI: Nausea, vomiting (more suggestive of torsion)
• MSK/Derm: Scrotal swelling, erythema, warmth
• Sexual health: Discharge, partner symptoms, recent unprotected intercourse

6. Collateral History and Family History

• Partner history: Symptoms in sexual partners (urethritis, cervicitis, PID) — partners from the prior 60 days should be tested and treated if STI is confirmed [3]
• Family history: Bell-clapper deformity or family history of testicular torsion (relevant for differential) [3]
• Social context: Occupation (prolonged sitting, bicycle riding), sexual practices, substance use

7. Risk Factors

• Sexually active males aged 14–35 (STI-related) [2][5]
• Men >35 years with bladder outlet obstruction (BPH) [1-2]
• Insertive anal intercourse (enteric organisms) [1]
• Recent urinary tract instrumentation, prostate biopsy, vasectomy [1]
• Amiodarone use [3]
• Prolonged sitting, bicycle riding, trauma [3]
• Urogenital abnormalities (especially in prepubertal boys with recurrent episodes) [5]
• Diabetes, immunosuppression — associated with more severe disease [1]

8. Differential Diagnosis

• Testicular torsion — surgical emergency; sudden onset, absent cremasteric reflex, high-riding testis, nausea/vomiting; salvage rate ~90% if surgery within 6 hours [3-4]
• Torsion of testicular appendage — gradual superior pole pain, "blue dot sign," normal cremasteric reflex; managed conservatively [3][7]
• Orchitis (mumps or viral) — testicular tenderness/swelling without primary epididymal involvement [5]
• Testicular tumor — painless mass, but can present with pain if hemorrhage occurs; evaluate with ultrasound [3]
• Inguinal hernia (incarcerated) — bowel sounds in scrotum, reducibility, abdominal symptoms [8]
• Fournier's gangrene — rapidly progressive scrotal erythema, crepitus, systemic toxicity [1]
• Testicular abscess or infarction [1]
• Idiopathic scrotal edema — bilateral painless edema, more common in children [8]

9. Past Medical History

• Prior episodes of epididymitis or orchitis (recurrent in prepubertal boys warrants GU workup) [5]
• History of STIs, UTIs, or prostatitis
• BPH or bladder outlet obstruction
• Recent urologic procedures or catheterization
• Immunosuppression, diabetes (risk for complicated disease) [1]
• TB exposure (chronic granulomatous epididymitis) [1]

10. Physical Exam

• Vital signs: Fever suggests more severe infection or alternative diagnosis
• Inspection: Unilateral scrotal swelling, erythema, edema [2-3]
• Palpation: Tender, swollen epididymis (posterior to testis); testis in normal anatomic position [2]
• Cremasteric reflex: Typically intact (absent in 14% of epididymitis vs. 100% of torsion) [4]
• Prehn sign: Pain relief with scrotal elevation — associated with epididymitis but insufficient sensitivity to rule out torsion [3]
• Urethral discharge: Milk the urethra; if present, obtain Gram stain [1]
• Blue dot sign: Absent (present in torsion of appendix testis) [7]
• Inguinal canal: Palpate for hernia [3]
• Transillumination: Reactive hydrocele may be present [3]

11. Lab Studies

• Urinalysis: Positive leukocyte esterase or ≥10 WBCs/HPF on spun first-void urine [1]
• Urine NAAT for C. trachomatis and N. gonorrhoeae — preferred specimen is first-void urine [1][5]
• Urine culture: To identify enteric organisms and guide susceptibility [1][5]
• Gram stain of urethral secretions: ≥2 WBCs per oil immersion field confirms urethritis; intracellular gram-negative diplococci diagnostic for gonorrhea [1]
• CBC, CRP: Elevated CRP and WBC may indicate more severe disease and need for hospitalization [1]
• HIV and syphilis screening if STI confirmed [9]
• Retest for GC/CT at 3 months [9]

12. Imaging

• First-line: Color Doppler ultrasound of the scrotum — imaging test of choice for acute scrotal pain [3][10]
  • Epididymitis findings: enlarged, hypoechoic epididymis with increased blood flow (hyperemia) on color Doppler; reactive hydrocele and scrotal wall thickening may be present [8][10]
  • Sensitivity of color Doppler for scrotal inflammation is nearly 100% [10]
• Torsion findings on US (to distinguish): Decreased/absent intratesticular blood flow, twisted spermatic cord ("whirlpool sign") [8][10]
• When imaging is unnecessary: If clinical presentation is classic for epididymitis (gradual onset, intact cremasteric reflex, tender epididymis, urinary symptoms) and torsion is low on the differential. However, if any diagnostic uncertainty exists, obtain US [10-11]
• Nuclear medicine scrotal scan: Largely replaced by Doppler US; sensitivity 89–98% for differentiating torsion from epididymitis [10]

13. Special Tests

• TWIST Score (Testicular Workup for Ischemia and Suspected Torsion): Used to risk-stratify acute scrotal pain for torsion — sensitivity 91%, specificity 95%, NPV 99% [3][12]
• Point-of-care ultrasound (POCUS): Highly accurate for acute scrotum evaluation by emergency physicians — sensitivity 96%, specificity 95% for torsion when assessing blood flow and whirlpool sign [11-12]
• Gram stain of urethral discharge: POC test to confirm urethritis and identify gonococcal infection [1]
• Mycoplasma genitalium testing: Consider in cases of persistent epididymitis not responding to standard therapy [13]

14. ECG

• Not routinely indicated for epididymitis
• Consider ECG if the patient is on amiodarone (a known cause of drug-induced epididymitis) to assess underlying cardiac condition and medication management [3]

15. Assessment

Acute epididymitis is a clinical diagnosis supported by gradual-onset unilateral scrotal pain, tender swollen epididymis, intact cremasteric reflex, and evidence of urethral inflammation or pyuria. [1-2] Etiology is age-dependent: STI-related in younger sexually active men, enteric organism-related in older men or those with urologic risk factors. [2][5] A causative pathogen is identified in approximately 88% of antibiotic-naive patients, with E. coli being the most common overall (56%) and STIs not restricted to patients <35 years. [14]

Complications include abscess formation, testicular infarction, chronic pain, infertility, and progression to epididymo-orchitis. [1-2] Chronic epididymitis (≥6 weeks) should raise suspicion for TB, fungal infection, or tumor. [1]

16. Treatment Plan

17. Disposition

• Discharge (majority of cases): Uncomplicated epididymitis with reliable follow-up, ability to tolerate oral medications, and no signs of systemic illness [1]
• Admission criteria:
  • Severe pain or high fever suggesting alternative diagnosis (torsion, abscess, necrotizing fasciitis) [1]
  • Inability to comply with outpatient antimicrobial regimen [1]
  • Older age, diabetes, elevated CRP — markers of more severe disease [1]
  • Suspected Fournier's gangrene or scrotal abscess requiring surgical intervention [1]
• Urology consultation: Diagnostic uncertainty, suspected torsion, abscess, recurrent epididymitis in prepubertal boys, or failure to improve [1][5]

18. Follow Up / Return Precautions

• Follow-up within 48–72 hours if symptoms are not improving [1][5]
• Complete resolution of discomfort may take several weeks after completing antibiotics — counsel patients accordingly [1]
• Return precautions: Worsening pain, new-onset fever, scrotal erythema spreading, nausea/vomiting, or failure to improve within 3 days [1]
• Persistent swelling/tenderness after completing antibiotics: Evaluate for tumor, abscess, infarction, testicular cancer, TB, or fungal infection [1]
• STI follow-up: Retest for GC/CT at 3 months; ensure partner treatment [9]
• Prepubertal boys with recurrent epididymitis: Evaluate for underlying genitourinary abnormalities [5]