RPhS: Phlebology Sonography: Venous Duplex, Reflux, and Procedure Guidance

What this domain tests

The RPhS phlebology sonography domain assesses lower-extremity venous duplex: normal and variant anatomy, venous hemodynamics, provocation techniques, reflux and obstruction criteria, and ultrasound guidance for venous intervention. Marks hinge on protocol precision-patient position, Doppler angle, provocation maneuver, and numeric thresholds-rather than broad recall.

Anatomy and hemodynamics you must map

• Deep veins: common femoral, femoral, popliteal, posterior tibial, peroneal, gastrocnemius, and soleal veins.
• Superficial veins: great saphenous vein (GSV), small saphenous vein (SSV), and accessory saphenous veins. Know the saphenofemoral junction (SFJ) and saphenopopliteal junction (SPJ).
• Perforators: medial calf Cockett perforators, Boyd and Dodd perforators; normal perforator flow runs superficial-to-deep.
• Venous return depends on competent valves and the calf muscle pump. Standing is the provocative position because hydrostatic pressure loads the valves.

Reflux testing rules

• Examine standing or in reverse Trendelenburg with the limb externally rotated and weight on the opposite leg.
• Use a linear 5–12 MHz transducer for superficial veins; lower frequency for obese or deep segments.
• Keep the spectral Doppler angle at 60° or less and sample mid-lumen.
• Provoke with Valsalva for junctional and upper-thigh segments; use distal manual augmentation for below-knee segments.
• Reflux thresholds: superficial veins >0.5 s, deep veins >1.0 s, perforators >0.35 s with outward (deep-to-superficial) flow.
• Record duration, diameter, level, and direction; color aliasing alone does not define reflux.

Worked example

A patient with medial calf varicosities is scanned standing. The GSV at the SFJ measures 7 mm and shows retrograde flow for 1.4 s after Valsalva. The common femoral vein shows 0.6 s after Valsalva and 0.3 s after distal augmentation. Interpretation: GSV/SFJ reflux is present because 1.4 s exceeds the superficial threshold of 0.5 s. The common femoral vein is normal because 0.6 s does not exceed the deep threshold of 1.0 s, and augmentation confirms competent deep flow. Do not label deep reflux from the 0.6-s Valsalva signal alone.

Traps that cost marks

• Applying the 0.5-s superficial threshold to deep veins or the 1.0-s deep threshold to the GSV.
• Calling brief valve-closure spikes reflux without meeting duration criteria.
• Measuring perforator reflux in the normal superficial-to-deep direction.
• Scanning supine without provocation, or using an angle above 60°.
• Confusing augmentation-induced antegrade flow with retrograde reflux.
• Omitting vein diameter and anatomic level, which are needed for procedural planning.