RVT Peripheral Venous Testing 2 — Questions and Answers
Question 1: Which duplex ultrasound finding is most diagnostic of acute deep vein thrombosis (DVT)?
- Absence of color flow in the vein
- Non-compressibility of the vein lumen (Correct answer)
- Increased echogenicity of the vessel wall
- Loss of phasic flow with respiration
Correct answer: Non-compressibility of the vein lumen
Non-compressibility of the vein with probe pressure is the primary criterion for diagnosing DVT on duplex ultrasound.
Question 2: When performing a lower extremity venous duplex exam, which vein is typically evaluated at the popliteal fossa?
- Small saphenous vein and popliteal vein (Correct answer)
- Great saphenous vein and femoral vein
- Anterior tibial vein and peroneal vein
- Gastrocnemius vein only
Correct answer: Small saphenous vein and popliteal vein
The popliteal fossa is the anatomical window where both the popliteal vein and the small saphenous vein are routinely evaluated.
Question 3: A patient presents with a swollen leg and pain. Duplex shows a hyperechoic, non-occlusive thrombus floating freely in the common femoral vein. What is the clinical concern?
- Chronic DVT with recanalization
- Free-floating thrombus with high pulmonary embolism risk (Correct answer)
- Extrinsic compression from lymph node
- Venous insufficiency with reflux
Correct answer: Free-floating thrombus with high pulmonary embolism risk
A free-floating thrombus in a major vein carries a significantly elevated risk of dislodgement and pulmonary embolism.
Question 4: Which Doppler waveform characteristic indicates normal venous patency in the common femoral vein?
- Continuous non-phasic flow
- Spontaneous phasic flow varying with respiration (Correct answer)
- High-resistance triphasic arterial pattern
- Absence of flow at rest with augmentation only
Correct answer: Spontaneous phasic flow varying with respiration
Normal femoral vein flow is spontaneous, phasic with respiration, and augments with distal compression.
Question 5: During a venous reflux study, what duration of retrograde flow in the great saphenous vein is considered pathological?
- Greater than 0.5 seconds
- Greater than 1.0 second (Correct answer)
- Greater than 2.0 seconds
- Any detectable retrograde flow
Correct answer: Greater than 1.0 second
Reflux duration exceeding 0.5 seconds in superficial veins (and 1.0 second in deep veins) is considered pathological by most accepted criteria.
Question 6: Which maneuver is most appropriate to assess venous reflux in the lower extremity during a duplex exam?
- Valsalva maneuver
- Distal limb compression and release (Correct answer)
- Proximal limb compression
- Elevation of the limb above heart level
Correct answer: Distal limb compression and release
Rapid release of distal manual compression or pneumatic cuff deflation generates retrograde flow to assess valve competence.
Question 7: What is the significance of a 'blunted' or non-phasic Doppler waveform in the common femoral vein?
- Normal variant in obese patients
- Suggests proximal obstruction such as iliac vein DVT (Correct answer)
- Indicates arteriovenous fistula
- Caused by deep breathing technique
Correct answer: Suggests proximal obstruction such as iliac vein DVT
Loss of respiratory phasicity in the femoral vein suggests an obstruction proximal to the interrogation site, such as iliac vein thrombosis.
RVT Peripheral Venous Testing 2
Which duplex ultrasound finding is most diagnostic of acute deep vein thrombosis (DVT)?