Duplex Ultrasound Imaging of the Lower Extremity Venous System – Review Flashcards

These flashcards cover anatomy, physiology, risk factors, scanning technique, normal and abnormal duplex findings, pathologies, incidental findings, and treatment principles for lower-extremity venous duplex ultrasound as described in Chapter 17 of the Wolters Kluwer text.

What are the three main components of Virchow’s triad?

Venous stasis, vessel wall injury, and hypercoagulable state

Which imaging modality is the first-line choice for diagnosing lower-extremity DVT?

Duplex ultrasound

Why are deep-system thrombi more likely to cause a life-threatening pulmonary embolism (PE) than superficial thrombi?

They are larger and located in veins compressed by surrounding muscles, increasing embolic risk.

What is the primary role of perforator veins?

To direct blood from superficial to deep veins and prevent prolonged pooling near the skin surface.

List three normal spectral Doppler characteristics of a healthy lower-extremity vein.

Spontaneous flow, respiratory phasicity, and augmentation with distal compression (plus flow cessation with proximal compression/ Valsalva).

Name four major risk factors for DVT from Table 17-1.

Any four of: Age, surgery/trauma, immobilization, past DVT, congenital/acquired coagulation disorders, malignancy, septicemia, birth-control pills, hormone replacement therapy, pregnancy, obesity, stroke, CHF, long-distance travel, inflammatory bowel disease, varicose veins.

Which superficial vein is the longest in the body and where does it join the deep system?

The great saphenous vein (GSV); it terminates into the common femoral vein at the saphenofemoral junction.

How often should transducer compressions be performed during a lower-extremity venous survey?

Every 2–3 cm down the entire leg in the transverse plane.

What patient position best fills the leg veins for ultrasound evaluation?

Reversed Trendelenburg with the patient supine, knee slightly flexed, hip externally rotated, and the legs dangling if calf veins need visualization.

Which transducer frequency range is typically used to examine femoral and popliteal veins?

A mid-range linear array transducer, 5–10 MHz.

How is an acute thrombus typically attached to the vein wall, and what is the clinical implication?

It is poorly attached, making it more likely to embolize.

Give two sonographic features that help distinguish acute from chronic post-thrombotic changes.

Acute: dilated vein, smooth borders, spongy/deformable thrombus; Chronic: normal or small vein, rigid non-deformable echogenic material, irregular surface, possible synechiae.

What Doppler pattern suggests iliac or IVC obstruction when sampling the CFV?

Continuous, non-phasic venous flow.

Which calf venous structure is a common storage site for blood and frequently harbors thrombus after prolonged immobility?

The soleal sinus veins.

Why are anterior tibial veins rarely included in standard DVT protocols?

Because thrombosis in the ATV is uncommon and the veins are deep with an unfavorable insonation angle.

What condition is characterized by compression of the left common iliac vein by the right common iliac artery?

May–Thurner syndrome

Define phlegmasia alba dolens.

Extensive iliofemoral DVT producing marked swelling, pain, pitting edema, and limb blanching (white leg).

What additional findings are typical of phlegmasia cerulea dolens compared with phlegmasia alba dolens?

Even more massive swelling, severe pain, limb cyanosis, complete venous outflow obstruction, potential arterial compromise and venous gangrene.

Which two provocative maneuvers are used to demonstrate venous competence on spectral Doppler?

Distal limb compression (augmentation) and proximal compression or Valsalva (flow cessation).

Describe the Well’s score threshold for a high probability of DVT.

A total of 3 or more points.

What laboratory test has a high sensitivity but low specificity for DVT?

D-dimer

Name three common nonvascular incidental findings detectable on lower-extremity venous ultrasound.

Cysts, hematomas, enlarged lymph nodes, abscesses, edema, tumors (any three).

What is the typical ultrasound appearance of edema in the calf?

Anechoic channels with a characteristic “ant farm” appearance in the subcutaneous tissues.

Which maneuver must NEVER be performed in the longitudinal plane during a venous exam?

Compression of the vein.

What are synechiae in the context of chronic post-thrombotic changes?

Thin, web-like strands of residual fibrous material spanning the venous lumen.

Which waveform abnormality may indicate right-sided heart failure or tricuspid insufficiency?

Pulsatile venous flow on spectral Doppler.

List two common vascular incidental findings on a venous duplex study.

Aneurysms, pseudoaneurysms, arteriovenous fistulas, significant arterial disease (any two).

What primary medical treatment is used for most cases of acute DVT?

Anticoagulation with agents such as heparin, low-molecular-weight heparin, warfarin, or new oral anticoagulants (NOACs).

What scanning approach may help compress the femoral vein through the adductor canal in a muscular patient?

Apply posterior pressure with the free hand while the transducer compresses anteriorly.

Why is caution advised when applying compression over a non-occlusive thrombus?

Because a free-floating tail may embolize during forceful compression.

Which imaging modalities are useful for evaluating iliac veins when ultrasound is limited?

Computed tomography venography and magnetic resonance venography.

How does the presence of color flow around a residual fibrous string inside a vein help with diagnosis?

It confirms recanalization and indicates chronic post-thrombotic change rather than acute thrombus.

What role do gradient elastic stockings play in DVT management?

They help reduce venous hypertension and prevent post-thrombotic syndrome.

Which veins join to form the tibioperoneal trunk?

The posterior tibial and peroneal veins.

What is the main venous outflow of the calf?

The femoral vein.

Describe the normal relationship of the common femoral vein (CFV) to the common femoral artery (CFA) at the groin crease.

The CFV lies medial to the CFA.

How can augmentation with distal compression help confirm patency of a vein?

A sudden increase in Doppler velocity indicates an unobstructed venous segment between the probe and the compression site.

What is the recommended protocol if one channel of a bifid femoral vein is thrombosed?

Evaluate and document both channels, as one may be patent while the other is thrombosed.

Why is thrombus in superficial veins less likely to result in PE compared to deep-system thrombus?

Superficial veins are smaller, have lower flow volumes, and are not subjected to muscular squeezing that can dislodge thrombi.

What patient history elements should be documented before a venous duplex exam?

Symptoms, onset, duration, prior DVT, surgeries/trauma, risk factors such as recent travel, immobilization, or hormone therapy.

Which superficial vein courses along the middle of the posterior calf and typically enters the popliteal vein?

The small saphenous vein (SSV).

What spectrum of echogenicity might an acute thrombus display on modern ultrasound machines?

Hypoechoic, hyperechoic, or heterogeneous (areas of both).

How does vein size typically differ between acute and chronic thrombotic states?

Acute: vein often dilated; Chronic: vein normal or reduced in caliber.

What is the main consequence of non-functioning perforator valves?

Blood pools in distal legs, leading to venous stasis changes and possible ulceration.

What finding on spectral Doppler suggests an obstruction between the probe and the site of distal limb compression?

No augmentation in venous flow during distal compression.

In duplex ultrasound terminology, why is the phrase “chronic thrombus” discouraged?

Studies show residual intraluminal material over time is often fibrous change, not true thrombus; preferred terms are acute, chronic post-thrombotic changes, or indeterminate.

What role do the gastrocnemius veins play in DVT evaluation?

They are paired calf tributaries that drain the gastrocnemius muscle and can harbor thrombus extending into the popliteal vein.

Describe the normal ultrasound appearance of venous valve leaflets.

Thin, mobile, echogenic membranes within a slight sinus dilation of the vein wall.

Why can bowel gas and vessel depth limit iliac vein ultrasound assessment?

They hinder acoustic penetration and prevent direct compression, necessitating reliance on color and spectral Doppler patterns.

Name two clinical symptoms that may suggest pulmonary embolism in a patient with suspected DVT.

Tachypnea, chest pain, tachycardia (any two).

What indicates a successful Valsalva maneuver on a normal venous Doppler tracing?

Cessation (or marked reduction) of forward venous flow during strain.

What term describes thin fibrous bands crossing a recanalized vein lumen?

Synechiae.

Which veins typically accompany an artery of the same name and carry the highest embolic risk?

Deep veins.

When is color Doppler added after compression imaging, and what does it assess?

In the longitudinal plane to evaluate flow direction, spontaneity, and to help identify residual lumen or thrombus.

Which imaging findings define a thrombosed vein on duplex?

Echogenic material within the lumen AND inability to fully compress the vein walls.

How does an arteriovenous fistula affect venous Doppler waveforms?

Introduces arterial pulsatility into the venous signal, producing an abnormal pulsatile pattern.

What maneuver can help verify dorsal foot venous flow in calf veins during ultrasound?

Distal manual foot compression (augmentation).

What is the purpose of thrombolytic therapy in selected DVT patients?

To actively dissolve thrombus, restore patency, and reduce the risk of post-thrombotic syndrome.

Which paired calf veins run adjacent to the fibula and are less superficial than PTVs?

Peroneal veins.

What indirect Doppler sign at the CFV implies unobstructed iliac/IVC flow?

Respiratory phasicity of the venous waveform.

Which chronic DVT change can narrow the lumen while still allowing central flow on color Doppler?

Recanalization with circumferential wall thickening.

What is the clinical significance of a calf palpable cord during physical exam?

It suggests superficial thrombophlebitis or a thrombosed superficial vein.

Why might a low-frequency curved-array transducer be chosen during a DVT study?

To image deep or central veins (IVC, iliac veins) in obese patients where penetration is required.

What is the main function of the tibioperoneal trunk?

To carry converged blood from posterior tibial and peroneal veins into the popliteal vein.

How can free-flowing tail thrombus be recognized on B-mode imaging?

As a mobile, echogenic strand attached proximally but floating distally within the vein lumen.

Name two major chronic complications of DVT aside from PE.

Post-thrombotic syndrome and chronic venous insufficiency.

Which vein becomes the popliteal vein after passing through the adductor canal?

The femoral vein.

What are the two most common treatment modalities besides anticoagulation for significant DVT?

Thrombolytic therapy and thrombectomy.