What is the initial diagnostic workup for a patient presenting with scrotal edema?

Diagnostic Workup for Scrotal Edema

Initial Approach

Begin with scrotal ultrasound with Doppler as the primary diagnostic modality, as it is the imaging test of choice for all scrotal abnormalities and can differentiate between the various causes of scrotal edema. 1

Clinical History and Physical Examination

Focus your clinical assessment on these specific elements:

• Onset and timing of symptoms: Abrupt onset suggests testicular torsion (surgical emergency), while gradual onset suggests epididymitis or other inflammatory conditions 1, 2
• Pain characteristics: Severe pain with negative Prehn sign (no relief with testicular elevation) suggests torsion, while painless or minimally painful edema suggests acute idiopathic scrotal edema 2, 3
• Age of patient: Prepubertal boys more commonly have torsion of testicular appendage or acute idiopathic scrotal edema, while adults over 25 typically have epididymitis 2
• Associated symptoms: Check for urinary symptoms, fever, trauma history, and sexual activity 4
• Physical examination specifics: Palpate the testis and epididymis separately, assess scrotal wall thickness, check for transillumination, examine the abdomen and inguinal region 4

Laboratory Testing

• Urinalysis is mandatory in all cases, though normal urinalysis does not exclude testicular torsion or epididymitis 2, 4
• Consider complete blood count and inflammatory markers if infection is suspected 5

Imaging Protocol

Duplex Doppler Ultrasound (First-Line Imaging)

Ultrasound should include three components 1, 2:

• Grayscale examination: Assess testicular homogeneity and identify the "whirlpool sign" of twisted spermatic cord (96% sensitivity for torsion) 1, 2
• Color Doppler assessment: Evaluate testicular perfusion (96-100% sensitivity for torsion) 1, 2
• Power Doppler: Particularly useful for detecting slow flow in prepubertal testes 1, 2

Specific Ultrasound Findings by Diagnosis

Testicular torsion 2:

• Decreased or absent blood flow to affected testicle
• "Whirlpool sign" of twisted spermatic cord
• Enlarged heterogeneous testis
• Ipsilateral hydrocele and scrotal wall thickening

Epididymitis/epididymo-orchitis 2:

• Enlarged epididymis with increased blood flow on Doppler
• Scrotal wall thickening and hydrocele common

Acute idiopathic scrotal edema 1, 6, 3:

• Marked scrotal wall thickening with heterogeneous striated appearance ("onion-like" layers)
• Increased scrotal wall vascularity
• Normal testes and epididymis with no increased testicular vascularity
• Reactive hydrocele may be present

Segmental testicular infarction 2:

• Classic wedge-shaped avascular area on ultrasound
• May also present as round lesions with variable flow

Critical Pitfalls to Avoid

• False-negative Doppler can occur with partial torsion or spontaneous detorsion - if clinical suspicion remains high despite normal ultrasound, proceed to surgical exploration 2
• Always use the contralateral asymptomatic testicle as an internal control during ultrasound evaluation 2
• Significant overlap exists in clinical presentation between different causes - do not rely on clinical examination alone 2
• Normal urinalysis does not exclude testicular torsion 2

When to Consider MRI

• MRI may be appropriate for very large scrotal masses where ultrasound is limited 1
• MRI is most sensitive for testicular torsion when ultrasound is equivocal, showing decreased or absent perfusion on dynamic contrast-enhanced sequences 1
• MRI can identify segmental testicular infarction when ultrasound is unclear 1

Urgent Surgical Consultation Criteria

Immediate urological consultation is required for 2:

• Any suspicion of testicular torsion (surgical intervention needed within 6-8 hours)
• High TWIST score (≥6) even without imaging
• Equivocal imaging with high clinical suspicion

Systemic Causes to Consider

When scrotal edema is bilateral and painless with characteristic "onion-like" ultrasound appearance, investigate for 6, 5:

• Heart failure
• Hepatic failure
• Lymphatic or venous obstruction
• Idiopathic lymphedema