Venous Reflux and Chronic Venous Insufficiency: Duplex Protocol

Venous reflux duplex is ordered before varicose vein ablation, sclerotherapy, or phlebectomy — the referring provider needs a complete map of the incompetent venous system. This is one of the more technically demanding peripheral vascular studies, and a thorough protocol is what makes the difference between a useful report and a useless one.

Anatomy You Need to Know

Great Saphenous Vein (GSV)

The GSV runs medially from the dorsal foot, up the medial leg, medial knee, medial thigh, and joins the common femoral vein (CFV) at the saphenofemoral junction (SFJ) — a few centimeters below the inguinal ligament. It runs within the "saphenous canal" between two fascial layers (the saphenous eye on transverse imaging).

Normal GSV diameter: < 4 mm at mid-thigh (supine); up to 6 mm may be acceptable.

Small Saphenous Vein (SSV)

The SSV runs posteriorly from the lateral ankle, up the midline of the posterior calf, and joins the popliteal vein at the saphenopopliteal junction (SPJ) — highly variable location (typically in the popliteal fossa, but can be high or duplicated).

Perforating Veins

Connect the superficial and deep systems through the fascia. Pathologic perforators (Cockett, paratibial) allow high-pressure deep system blood to reflux into superficial veins.

Deep System

Common femoral, femoral (formerly superficial femoral), popliteal, posterior tibial, peroneal veins — reflux here usually indicates post-thrombotic disease.

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What Is Pathologic Reflux?

Normal venous blood moves proximally (from foot to heart). Valvular incompetence allows retrograde flow (reflux) when pressure above the valve exceeds pressure below.

Definition of pathologic reflux: Retrograde flow duration > 0.5 seconds in superficial veins (GSV, SSV) after augmentation or Valsalva.

• Deep veins: > 1.0 second (more forgiving because they handle higher volumes)
• Perforating veins: outward flow (deep to superficial) > 0.5 seconds and diameter > 3.5 mm

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Patient Position and Setup

Position: Upright (standing) is the most physiologically accurate position for reflux testing — gravity loads the veins. Most labs use a tilt table or have the patient stand holding a wall or bar.

• If upright not possible, reverse Trendelenburg (30–45°) is acceptable
• Supine position significantly underestimates reflux

Probe: 5–12 MHz linear transducer.

Color and spectral Doppler: Essential for all assessment.

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Augmentation Technique

Two methods to provoke reflux:

1. Manual calf squeeze (augmentation): Squeeze the calf firmly and release. A normal valve closes quickly; incompetent valves allow sustained retrograde flow.

2. Valsalva: For the SFJ — ask the patient to bear down. This raises abdominal pressure and loads the saphenofemoral junction.

Critical: Measure reflux duration from release of squeeze (or end of Valsalva), not the duration of augmentation flow.

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Scanning Protocol

Step 1: Deep System Survey (DVT Exclusion)

Before mapping superficial reflux, compress the deep veins from groin to calf. Establish:

• No DVT (prior DVT causes post-thrombotic reflux — important context)
• Deep system reflux (if present, note it — affects management)

Step 2: Saphenofemoral Junction (SFJ)

Probe position: Medial groin, at the inguinal crease.

1. Identify the CFV in transverse — large, easily compressible vein medial to CFA
2. Follow the CFV caudally until you see the GSV junction (comes in medially, inferiorly)
3. Measure the SFJ diameter
4. Interrogate with spectral Doppler in long axis
5. Apply Valsalva — look for retrograde flow

Document:

• SFJ reflux: present / absent, duration (seconds), waveform
• Anterior accessory saphenous vein (AASV): look for it just lateral to the SFJ — a common source of thigh varicosities

Step 3: Great Saphenous Vein — Full Mapping

Technique: Transverse image of the GSV every few centimeters, medial thigh → medial calf.

1. Identify the GSV in transverse — look for the "Egyptian eye" (GSV within fascial envelope)
2. Measure diameter at: upper thigh, mid-thigh, knee, upper calf, mid-calf
3. At each level, squeeze calf and check for reflux in long axis
4. Document where reflux stops (e.g., "reflux extends to the upper calf, terminates at 30 cm from SFJ")

Normal GSV: Collapses with compression, no reflux, runs within saphenous fascia.

Incompetent GSV: Fails to collapse, dilated, shows retrograde flow after augmentation.

Step 4: Saphenopopliteal Junction (SPJ) and SSV

Position: Patient facing away from you; probe on posterior knee.

1. Identify the popliteal vein — deep, non-pulsatile, compressible
2. Find the SSV junction — variable location (scan high in the popliteal fossa and distally)
3. Measure SPJ diameter
4. Map SSV distally down the posterior calf to the ankle

Note: The SPJ is the most variable junction in the venous system. Some SSVs have high junctions, some join tributaries rather than the popliteal directly. Document what you find, not what you expect.

Step 5: Perforating Veins

Look along the medial leg for perforators connecting deep and superficial systems through the fascia:

• Paratibial perforators (medial leg)
• Posterior tibial perforators (Cockett perforators) — medial ankle region

A pathologic perforator shows outward (deep to superficial) flow ≥ 0.5 sec and diameter ≥ 3.5 mm. Document: location (distance from medial malleolus), diameter, flow direction.

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CEAP Classification (Clinical Reference)

The CEAP classification is the standard for staging CVI:

Class	Finding
C0	No visible/palpable disease
C1	Telangiectasias or reticular veins
C2	Varicose veins
C3	Edema
C4a	Pigmentation or eczema
C4b	Lipodermatosclerosis or atrophie blanche
C5	Healed venous ulcer
C6	Active venous ulcer

Document the patient's clinical class; it guides urgency of treatment.

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Reporting Language

Saphenofemoral junction reflux: "Reflux at the saphenofemoral junction — retrograde flow duration 2.4 seconds with Valsalva. Incompetent GSV with reflux extending from the SFJ to the mid-calf (approximately 40 cm). GSV diameter: 8 mm at mid-thigh, 6 mm at mid-calf. Small saphenous vein: no significant reflux at the saphenopopliteal junction. No pathologic perforators identified."

Perforator disease: "Incompetent perforating vein identified on the medial leg, 12 cm above the medial malleolus. Diameter 4.2 mm with outward flow of 0.8 seconds duration after augmentation."

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SonoBuddy's vascular protocols include DVT, ABI, and venous reflux duplex guides.