In a male patient with acute scrotal pain and a negative urinalysis, what is the appropriate next diagnostic step?

Immediate Scrotal Ultrasound with Color Doppler is the Next Step

In a male patient with acute scrotal pain and negative urinalysis, proceed directly to scrotal ultrasound with color Doppler imaging—this is the definitive diagnostic test to rule out testicular torsion, which is a surgical emergency requiring intervention within 6-8 hours to prevent testicular loss 1.

Why Ultrasound is Essential Regardless of Urinalysis Results

The negative urinalysis does not exclude testicular torsion, which is the most critical diagnosis to identify or exclude. Here's the clinical reasoning:

The Diagnostic Challenge

• Testicular torsion, torsion of testicular appendage, and epididymitis account for 85-90% of acute scrotal pain cases 1
• These three conditions have overlapping clinical presentations that make them clinically indistinguishable on examination alone 1
• Urinalysis has poor sensitivity (58.2%) for epididymo-orchitis and provides minimal diagnostic value in the acute scrotal pain workup 2

Why Urinalysis Results Don't Change Your Next Step

A negative urinalysis:

• Does not rule out epididymitis (sensitivity only 58.2%) 2
• Does not provide any information about testicular torsion
• Changed management in only 5.2% of cases in one study 2
• The diagnosis is primarily driven by ultrasound results, not urinalysis 2

The Ultrasound Findings You're Looking For

Testicular Torsion (Surgical Emergency)

• Absent or decreased blood flow to the affected testis on color Doppler 3, 4
• Sensitivity of 78.8% and specificity of 98.1% 2
• Must be identified within 6-8 hours of symptom onset to prevent testicular loss 1

Epididymitis/Epididymo-orchitis

• Increased blood flow to the epididymis and testis on color Doppler 3, 4
• Most common cause in adolescent boys and adults 1
• More insidious onset compared to torsion 1

Torsion of Testicular Appendage

• Most common in prepubertal boys 1
• May show focal hyperemia adjacent to the appendage 4

Critical Time-Sensitive Considerations

Do not delay imaging to obtain additional laboratory studies. The 6-8 hour window for testicular salvage in torsion cases is absolute 1. Every minute counts when testicular torsion is in the differential diagnosis.

Common Pitfalls to Avoid

• Don't rely on clinical signs alone: The Prehn sign (pain relief with testicular elevation) is unreliable and should not delay imaging 1
• Don't wait for urinalysis results: Even if not yet resulted, proceed with ultrasound 2
• Don't assume negative urinalysis means no infection: Epididymitis can occur with negative urinalysis 2
• Don't use urinalysis to triage imaging: All patients with acute scrotal pain require ultrasound evaluation 1

If Ultrasound is Equivocal

In rare cases where color Doppler ultrasound is indeterminate (particularly in children with small testicles where flow may be difficult to detect):

• Consider contrast-enhanced ultrasound or microvascular imaging ultrasound as problem-solving techniques 1
• Surgical exploration remains the gold standard when torsion cannot be excluded and clinical suspicion is high 1

The bottom line: A negative urinalysis provides no reassurance against testicular torsion and minimal diagnostic value overall in acute scrotal pain—proceed immediately to scrotal ultrasound with color Doppler.