What are the causes of penile and scrotal edema?

Causes of Penile and Scrotal Edema

Life-Threatening and Urgent Causes

Testicular torsion is the most critical diagnosis to exclude in any patient presenting with acute scrotal edema, as testicular viability is compromised if surgical intervention is not performed within 6-8 hours of symptom onset. 1, 2

Testicular Torsion

• Presents with sudden onset of severe scrotal pain and swelling, with scrotal edema developing secondary to venous and lymphatic obstruction from the twisted spermatic cord 1
• More common in adolescents with bimodal distribution peaking in neonates and postpubertal boys 1, 2
• Emergency Doppler ultrasound shows decreased or absent blood flow to the affected testicle and the pathognomonic "whirlpool sign" of the twisted spermatic cord 1
• Critical pitfall: Normal urinalysis does not exclude testicular torsion 1, 2
• Requires immediate urological consultation and surgical exploration within 6-8 hours 2

Epididymitis/Epididymo-orchitis

• The most common cause of acute scrotal swelling in men younger than 35 years of age, representing approximately 600,000 cases annually in the United States 2, 3
• Presents with gradual onset of pain and scrotal swelling, in contrast to the abrupt onset of torsion 2
• For sexually transmitted causes (age <35 years): Treat with ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days 4, 1
• For enteric organisms or patients >35 years: Use ofloxacin 300 mg orally twice daily for 10 days or levofloxacin 500 mg orally once daily for 10 days 4, 1
• Adjunctive therapy includes bed rest, scrotal elevation, and analgesics until fever and inflammation subside 4, 1
• Critical pitfall: Failure to improve within 3 days mandates reevaluation for abscess, infarction, testicular cancer, or tuberculous/fungal epididymitis 4, 1

Fournier's Gangrene/Necrotizing Fasciitis

• Beta-hemolytic streptococci or clostridial species cause cellulitis of the scrotum and penis with rapid fluid accumulation between Colles' and Buck's fascia, producing intense scrotal swelling 5
• If not immediately decompressed by linear incisions, devascularization of scrotal and penile skin occurs, resulting in gangrene 5
• Requires immediate treatment with penicillin and radical debridement of necrotic tissue if gangrene develops 5

Infectious Causes

Lymphogranuloma Venereum (LGV)

• Caused by Chlamydia trachomatis serovares L1, L2, or L3, manifesting as painful inguinal and/or femoral lymphadenopathy that is usually unilateral 1
• Leads to secondary scrotal and penile edema through lymphatic obstruction 1

Streptococcal Cellulitis

• Caused by beta-hemolytic streptococci without a discernible portal of entry in the majority of instances 5
• Produces intense swelling of the scrotum due to fluid accumulation in the closed fascial space 5

Inflammatory and Systemic Causes

Crohn's Disease (Metastatic Crohn's Disease)

• Penile and scrotal swelling can occur as an extraintestinal manifestation of Crohn's disease, representing an uncommon form of metastatic Crohn's disease 6
• In 88% of pediatric patients, cutaneous symptoms precede the formal diagnosis of Crohn's disease, with two-thirds having no gastrointestinal symptoms at initial presentation 6
• Critical diagnostic point: An evaluation for Crohn's disease is necessary in all patients presenting with unexplained genital swelling 6
• Treatment of the underlying Crohn's disease with systemic medications is most effective 6

Lymphedema

• Can result from surgery (particularly abdominal/pelvic procedures), chemotherapy, or radiation therapy 7
• Presents with progressive swelling, pain, discomfort, and difficulties with ambulation and urination 7
• Treatment involves continuous use of compression garments together with thorough hygiene and skin care 7

Benign and Self-Limited Causes

Acute Idiopathic Scrotal Edema

• A rare, self-limiting condition primarily affecting prepubertal boys but can occur in adults 1, 2
• Characterized by painless or minimally painful marked scrotal wall thickening 1, 2
• This is a diagnosis of exclusion after ruling out testicular torsion, epididymitis, and other surgical emergencies 1

Hydrocele

• Presents as a fluid collection around the testis that demonstrates complete transillumination 1
• While typically not causing severe edema, large or tense hydroceles can contribute to scrotal swelling 1
• Critical pitfall: Hydroceles can occasionally mask underlying testicular tumors, particularly in young men 1

Diagnostic Approach Algorithm

Step 1: Assess timing and severity of onset

• Sudden, severe pain → Consider testicular torsion as surgical emergency 2
• Gradual onset → Consider epididymitis or other inflammatory causes 2

Step 2: Evaluate age and risk factors

• Age <35 years with sexual activity → Consider sexually transmitted epididymitis 4, 3
• Age >35 years → Consider enteric organism epididymitis or other causes 4
• Prepubertal boys → Consider acute idiopathic scrotal edema or torsion of testicular appendage 1, 2

Step 3: Perform urgent Doppler ultrasound

• Look for decreased/absent blood flow and "whirlpool sign" for torsion 1, 2
• Look for increased epididymal blood flow for epididymitis 2
• Assess for hydrocele, abscess, or tumor 1

Step 4: Obtain appropriate laboratory studies

• Gram-stained smear of urethral exudate for urethritis diagnosis 4
• Culture or nucleic acid amplification test for N. gonorrhoeae and C. trachomatis 4
• First-void uncentrifuged urine for leukocytes if urethral Gram stain is negative 4

Step 5: Consider systemic causes if no local pathology identified

• Evaluate for Crohn's disease in unexplained cases, especially in pediatric patients 6
• Assess for recent surgery, chemotherapy, or radiation suggesting lymphedema 7
• Consider LGV if inguinal lymphadenopathy is present 1