What are typical PRFs for venous and arterial Doppler flow?

• A. Venous 14 cm/sec; Arterial 32 cm/sec
• B. Venous 32 cm/sec; Arterial 14 cm/sec
• C. Venous 10 cm/sec; Arterial 40 cm/sec
• D. Venous 16 cm/sec; Arterial 28 cm/sec

Answer: (A)

Understanding the velocity scale used in spectral Doppler is the key idea. Venous blood moves slowly, while arterial blood travels much faster. To visualize slow venous flow clearly, you set a lower velocity scale (lower PRF). To capture the higher arterial velocities without losing information or producing aliasing, you use a higher velocity scale (higher PRF). The typical pairing that reflects this difference is venous around 14 cm/s and arterial around 32 cm/s. This setup keeps the venous signal well resolved on the low end while allowing the arterial signal to be measured with a higher scale. The other options either reverse these roles or use values that don’t fit the common venous vs arterial velocity ranges.