Venous Reflux Time and Vein Size

Reflux Time and Size Criteria for Incompetence 

Iliac vein stenosis, obstruction or May-Thurner Syndrome (MTS)

1. Venous Doppler waveforms may have normal phasic flow

2. Only see continuous or elevated flow in very high-grade stenosis

3. No flow with spectral Doppler indicates occlusion

4. Difference in flow lumen or Doppler waveforms comparing right to left side

5. Transverse vein diameter measurement is 1/3 or less the diameter of the contralateral iliac vein, generally < 3mm in diameter

6. Brightly echoic walls due to significant scarring over time

7. Left common iliac vein confluence at 90 degrees

Note: Vein compression is a dynamic, not static process