What is the normal Doppler (Digital Optical Pulse Encoder and Receiver) arterial flow to the testicles?

Normal Doppler Arterial Flow to Testicles

Normal testicular arterial flow on Doppler ultrasound is characterized by low-resistance waveforms with continuous diastolic flow, with peak systolic velocities typically ranging from 5-15 cm/sec in the intratesticular arteries and up to 25 cm/sec in the supratesticular region. 1

Anatomical Considerations

The testicular artery can be evaluated in several locations, with different normal parameters at each:

1. Supratesticular artery (SA) - Located in the spermatic cord

   • Proximal: Higher resistance, PSV ~23 cm/sec, RI ~0.8 2
   • Medial: Moderate resistance, PSV ~17 cm/sec, RI ~0.7 2
   • Distal: Lower resistance, PSV ~12 cm/sec, RI ~0.5 2

2. Capsular artery (CA) - Along the testicular surface

   • PSV ~11 cm/sec, RI ~0.4 2

3. Intratesticular artery (IA) - Within testicular parenchyma

   • PSV ~5-6 cm/sec, RI ~0.4 2

Normal Doppler Parameters

Adult Males

• Resistive Index (RI): 0.4-0.6 (normal range) 1
• Pulsatility Index (PI): 0.5-1.0 (normal range) 1
• End Diastolic Velocity (EDV): Present and continuous 1
• Peak Systolic Velocity (PSV): Varies by location (see above) 2

Age-Related Differences

• Prepubertal boys (testicular volume ≤4 cm³):

  • Higher RI (0.39-1.0, mean 0.87)
  • Diastolic flow may be undetectable in normal testes (RI=1.0) in 67% of cases 3

• Pubertal/postpubertal boys (testicular volume >4 cm³):

  • Lower RI (0.43-0.75, mean 0.57)
  • Continuous diastolic flow similar to adult pattern 3

Clinical Significance

Understanding normal testicular arterial flow is critical for diagnosing conditions that affect testicular blood flow and viability:

• Testicular torsion: Absent or reversed diastolic flow, increased RI >0.7, decreased or absent PSV 1
• Epididymo-orchitis: Increased blood flow, decreased RI (typically <0.5), increased PSV 1
• Partial testicular torsion: Variability in waveform amplitude, monophasic waveform, tardus-parvus morphology 1

Important Diagnostic Pitfalls

1. Age-related variations: Normal prepubertal testes may show absent diastolic flow, which could be misinterpreted as pathological in younger patients 3

2. Partial torsion: May show preserved arterial flow despite ongoing ischemia, leading to false-negative diagnoses 1

3. Torsion/detorsion: May show reactive hyperemia that mimics epididymo-orchitis 1

4. Evolution of testicular infarction: Reversal of diastolic flow is an ominous sign of impending infarction in cases of severe epididymo-orchitis 4

5. Examination technique: The contralateral asymptomatic testicle should always be used as an internal control 1

6. Anatomical location: Measurements vary significantly based on which portion of the testicular artery is sampled 2

Optimal Assessment Technique

For comprehensive evaluation:

• Perform spectral Doppler analysis at the upper, mid, and lower poles of each testicle 1
• Use power Doppler for increased sensitivity to low-flow states, especially in prepubertal testes 1
• Compare findings with the contralateral testicle 1
• Document both arterial and venous flow patterns 1

Understanding these normal parameters helps clinicians accurately diagnose conditions like testicular torsion, which requires immediate surgical intervention to prevent testicular loss and preserve fertility 5.