Epididymitis and Orchitis

Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Patients with concomitant sexually transmitted diseases (STDs) may present with lower urinary tract symptoms. Diagnosis is based on clinical findings and urinalysis with culture. Scrotal ultrasound may show increased blood flow to the affected epididymis or testicle. Treatment is with empiric gram-negative coverage antibiotics and culture-directed therapy. Supportive care includes scrotal support and non-steroidal anti-inflammatory drugs.

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  • Epididymitis: acute inflammation of the epididymis due to viral or bacterial infections
  • Orchitis: acute inflammation of the testis due to viral or bacterial infections
  • Disease spectrum: Epididymitis can often progress to epididymo-orchitis if untreated.

Epidemiology and etiology

Epididymitis and orchitis are the most common causes of scrotal pain in adults (> 600,000 cases per year in the United States).


  • Acute epididymitis (often related to infectious causes): 
    • < 35-years-old: Chlamydia trachomatis (C. trachomatis), Neisseria gonorrhea (N. gonorrhea)
    • > 35-years-old: Escherichia coli (E. coli) and Pseudomonas related to urinary tract infection (UTI) or prostatitis 
  • Chronic epididymitis (noninfectious or chronic infectious origin): 
    • Genitourinary trauma history 
    • Greater than 3-month symptom duration 
    • Autoimmune immunoglobulin A (IgA) vasculitis 
  • Amiodarone: 
    • Secondary to high drug concentrations at the head of the epididymis 
    • Occurs in about 3%–11% of patients 
  • Rarely, isolated orchitis occurs secondary to mumps or other viruses (in nonimmune individuals).

Clinical presentation

  • Gradual onset testicular pain, swelling, and tenderness
  • Fevers
  • Redness and warmth in the scrotum
  • Lower urinary tract symptoms: 
    • Dysuria
    • Hematuria 
    • Urinary frequency 
    • Urinary urgency
Painless mass in scrotum

Epididymo-orchitis: presenting with swollen and tender right testicle, which appears larger compared to the normal left testicle

Image: “Painless mass” by Division of Pediatric Surgery, Oita Prefectural Hospital, 476 Bunyou Oita, Japan. License: CC BY 2.0

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Diagnosis and Management

Clinical findings

  • Positive Prehn’s sign: decreased pain with elevation of testicle
  • Urinalysis/culture: usually with pyuria and/or bacteriuria
  • Sexually transmitted disease (STD) screening: 
    • Urine nucleic acid amplification test (NAAT) for N. gonorrhoeae and C. trachomatis
    • Consider treating partner when applicable

Scrotal color Doppler ultrasound

  • Increased blood flow and inflammation of epididymis or testis
  • Assists in distinguishing testicular torsion with decreased testicular blood flow
Scrotal doppler ultrasound

Testicular ultrasound depicting the inflamed epididymis (B) with increased blood flow (A) (normal blood flow to the testicle)

Image: “Right scrotal ultrasound with color Doppler” by University of Pittsburgh, Graduate School of Medicine, 401 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA. License: CC BY 3.0


  • Scrotal support and non-steroidal anti-inflammatory drugs
  • For patients under 35-years-old, consider STD coverage: 
    • Regimen: ceftriaxone + doxycycline/azithromycin 
    • Fluoroquinolones, not an option if gonorrhea suspected due to resistance
  • For patients over 35-years-old, consider coverage for uropathogens: 
    • Levofloxacin 
    • Trimethoprim/sulfamethoxazole if unable to tolerate fluoroquinolones

Differential Diagnosis

  • Urinary tract infection (UTI): very common bacterial infection of the lower genitourinary system, which is effectively treated with antibiotics. The patient presents with dysuria, hematuria, suprapubic tenderness, or sometimes flank pain. Diagnosis is clinical with urinalysis and urine culture. 
  • Testicular torsion: acute-onset severe testicular pain in an adolescent boy, typically without an inciting event, is highly suspicious for torsion. Additional clinical findings include a hard testicle, swollen scrotum, and negative cremasteric reflex. Doppler ultrasound (showing no blood flow to the affected testicle) should not delay definitive management, which is acute surgical exploration and orchidopexy.
  • Prostatitis: bacterial infection of the prostate gland leading to lower urinary tract symptoms. Patients often present with dysuria, pelvic pain, urinary frequency, urgency, irritative voiding, and fevers. Diagnosis is clinical with a urinalysis, culture, and, if needed, a transrectal ultrasound. Treatment consists of long-term gram-negative coverage antibiotics.


  1. Eyre, R.C. (2021). Acute scrotal pain in adults. UpToDate. Retrieved January 27, 2021, from https://www.uptodate.com/contents/acute-scrotal-pain-in-adults
  2. Eyre, R.C. (2020). Nonacute scrotal conditions in adults. UpToDate. Retrieved January 27, 2021, from https://www.uptodate.com/contents/nonacute-scrotal-conditions-in-adults

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