What is the differential diagnosis (ddx) and management for scrotal swelling in a 2-year-old (2yo) patient?

Differential Diagnosis for Scrotal Swelling in a 2-Year-Old

In a 2-year-old with scrotal swelling, testicular torsion must be ruled out immediately as it is a surgical emergency requiring intervention within 6-8 hours, though torsion of testicular appendage is actually the most common cause of acute scrotal pain in this prepubertal age group. 1

Age-Specific Differential Diagnosis

The differential diagnosis in a 2-year-old differs significantly from older children and adults:

Most Common Causes in This Age Group

• Torsion of testicular appendage - This is the most common cause of testicular pain in prepubertal boys, including 2-year-olds 1

  • The pathognomonic "blue dot sign" is only visible in 21% of cases 1
  • Often presents with gradual onset pain and localized tenderness at the upper pole of the testis 1

• Testicular torsion - While less common than appendage torsion in this age, it remains a critical diagnosis that cannot be missed 1

  • Has a bimodal distribution with peaks in neonates and postpubertal boys, but can occur at any age including 2-year-olds 2
  • Presents with abrupt onset of severe scrotal pain, often with nausea and vomiting 2
  • Negative Prehn sign (pain NOT relieved with testicular elevation) distinguishes it from epididymitis 1, 2

• Epididymitis/epididymo-orchitis - Less common in prepubertal children but still possible 1

  • Characterized by gradual onset of pain 1
  • May have abnormal urinalysis, though normal urinalysis does not exclude it 1

Other Important Considerations

• Acute idiopathic scrotal edema - A rare, self-limiting condition primarily affecting prepubertal boys 1

  • Usually painless or minimally painful with marked scrotal wall thickening 1
  • Diagnosis of exclusion 1

• Incarcerated inguinal hernia - Must be considered emergent until proven otherwise 3

• Hydrocele - Can present as scrotal swelling, typically painless 1

Critical Diagnostic Approach

Immediate Clinical Assessment

Any acute scrotal pain or swelling must be treated as testicular torsion until proven otherwise. 1

Key clinical features to assess:

• Onset timing: Abrupt (minutes) suggests torsion; gradual (hours to days) suggests appendage torsion or epididymitis 1, 2
• Pain severity: Severe pain with nausea/vomiting strongly suggests testicular torsion 2
• Prehn sign: Negative (no relief with elevation) suggests torsion 1, 2
• Cremasteric reflex: Absent in testicular torsion 4
• Scrotal appearance: Rapid swelling and redness within minutes to 1-2 days suggests torsion 2

Imaging Protocol

• Duplex Doppler ultrasound is the first-line imaging modality when diagnosis is uncertain 1, 2
  • Grayscale examination should assess for the "whirlpool sign" of twisted spermatic cord (96% sensitivity) 1
  • Color Doppler assessment of testicular perfusion has 96-100% sensitivity 1
  • Power Doppler is particularly useful in prepubertal children like 2-year-olds who normally have slow flow 1
  • Use the contralateral asymptomatic testicle as an internal control 1

Critical Pitfall in This Age Group

False-positive Doppler evaluations can occur in infants and young boys who often have normally reduced intratesticular blood flow, potentially leading to unnecessary surgery. 1 This makes clinical correlation absolutely essential in 2-year-olds.

Management Algorithm

High Clinical Suspicion for Testicular Torsion

• Immediate urological consultation and emergent surgical exploration WITHOUT waiting for imaging 1, 2
• Time is critical: testicular viability compromised after 6-8 hours 1, 2
• Surgical outcomes are better when surgery occurs within 12 hours 1

Intermediate Suspicion

• Urgent Duplex Doppler ultrasound 1
• If ultrasound shows decreased/absent flow or whirlpool sign: immediate surgical exploration 1
• If ultrasound shows normal flow but clinical suspicion remains: still consider surgical exploration as false-negative rates can reach 30% 1

Confirmed Appendage Torsion

• Conservative management is appropriate for most cases 5
• However, surgical treatment may be indicated if:
  • Diagnosis cannot completely rule out testicular torsion 5
  • Severe inflammation present (hard scrotum or scrotal erythema) 5
  • Pain recurs after conservative treatment 5
• Surgery is safe, shortens hospital stay (median 2.0 vs 3.5 days), and prevents recurrence 5

Confirmed Epididymitis

• Bed rest, scrotal elevation, and analgesics 1
• Appropriate antibiotic therapy based on age and risk factors 1

Key Takeaway for 2-Year-Olds

The significant overlap in clinical presentation between testicular torsion, appendage torsion, and other causes makes diagnosis challenging in this age group. 1 When in doubt, surgical exploration is warranted as the consequences of missing testicular torsion (permanent testicular loss) far outweigh the risks of negative exploration. The normally reduced blood flow in prepubertal testes makes ultrasound interpretation particularly challenging, requiring experienced interpretation and strong clinical correlation. 1