What Is Pathologic Reflux?
Venous reflux is retrograde flow through an incompetent valve. Pathologic reflux is defined as reversed flow lasting longer than 0.5 seconds in superficial veins and longer than 1.0 seconds in deep veins.
Exam Setup
Perform the exam with the patient standing, weight-bearing on the contralateral leg. Apply generous gel and use the lightest probe pressure possible.
Augmentation Techniques
- Manual calf squeeze and release: Rapidly squeeze the calf to push blood proximally, then release. Competent valves close; incompetent valves allow retrograde flow.
- Valsalva maneuver: Patient bears down against a closed glottis. Standard for the saphenofemoral junction and proximal GSV.
Doppler Settings by Machine
- MX7: Color PRF 1000-1500 Hz, Wall Filter 50-100 Hz, Smart Track ON.
- M8 Elite: Same PRF and wall filter. iClear enhances tissue-flow boundary. Smart Track ON.
- Resona i9T: V Flow for angle-independent velocity mapping at junctions.
- Consona N9: Color PRF 1000-1500 Hz, Wall Filter low. D Trace for automated spectral envelope.
Measuring Reflux Duration
Place the spectral Doppler gate within the vein lumen, angle-corrected to 60 degrees or less. Perform augmentation. Measure from onset to cessation of reversed flow.
Frequently Asked Questions
What PRF for venous reflux assessment?
Start with 1000-1500 Hz. Adjust down if not seeing flow, up if too much artifact.
Standing or supine?
Standing is the standard. Supine measurements are not accepted by most insurance carriers.
How long is pathologic reflux?
>0.5 seconds superficial, >1.0 seconds deep.
What is Smart Track?
Automatic Doppler angle correction and sample volume tracking on MX7 and M8 Elite.