VT DVT & Venous Reflux Assessment 3 — Questions and Answers
Question 1: May-Thurner syndrome results in DVT risk due to compression of which vessel?
- Right common iliac artery by the left common iliac vein
- Left common iliac vein by the right common iliac artery (Correct answer)
- Inferior vena cava by the aorta
- Left femoral vein by the inguinal ligament
Correct answer: Left common iliac vein by the right common iliac artery
May-Thurner syndrome occurs when the right common iliac artery compresses the left common iliac vein against the lumbar spine, promoting left iliac DVT.
Question 2: During a lower extremity venous duplex, respiratory phasicity is absent in the common femoral vein. The MOST likely cause is:
- Patient anxiety causing breath-holding
- Proximal obstruction at the iliac or IVC level (Correct answer)
- Distal calf DVT
- Superficial venous reflux
Correct answer: Proximal obstruction at the iliac or IVC level
Loss of normal respiratory phasicity in the common femoral vein indicates proximal obstruction, typically at the iliac vein or IVC level.
Question 3: Which statement about perforator vein reflux is CORRECT?
- Outward flow during calf muscle relaxation is normal
- Inward flow during calf relaxation indicates incompetence
- Outward flow lasting >0.5 s during calf compression-release indicates incompetence (Correct answer)
- Perforator reflux cannot be assessed with duplex ultrasound
Correct answer: Outward flow lasting >0.5 s during calf compression-release indicates incompetence
Perforator incompetence is defined as outward (superficial-directed) flow exceeding 0.5 seconds during calf compression-release maneuver.
Question 4: A patient presents with unilateral leg swelling, and duplex shows a non-compressible popliteal vein with echogenic content. The vein diameter is reduced compared to contralateral side. This MOST likely represents:
- Acute DVT
- Chronic DVT with scarring (Correct answer)
- Baker's cyst
- Lymphedema
Correct answer: Chronic DVT with scarring
Reduced vein diameter, hyperechoic content, and non-compressibility together indicate chronic DVT with organized thrombus and fibrosis.
Question 5: The normal direction of blood flow in a competent perforating vein is:
- Superficial to deep during calf muscle contraction (Correct answer)
- Deep to superficial during calf muscle contraction
- Bidirectional at all times
- Superficial to deep during muscle relaxation only
Correct answer: Superficial to deep during calf muscle contraction
In healthy perforators, muscle contraction drives flow inward (superficial to deep) toward the deep venous system.
Question 6: What is the primary advantage of using a high-frequency linear transducer (10–15 MHz) for calf vein DVT assessment?
- Better penetration into deep pelvic structures
- Superior spatial resolution for small, paired calf veins (Correct answer)
- Wider field of view for the entire thigh
- Reduced need for compression maneuvers
Correct answer: Superior spatial resolution for small, paired calf veins
High-frequency transducers provide superior axial and lateral resolution needed to identify small-caliber, paired calf veins and subtle thrombus.
Question 7: In assessing the small saphenous vein (SSV) for reflux, the patient is BEST positioned:
- Supine with leg elevated 30°
- Standing or reverse Trendelenburg
- Prone with knee slightly flexed (Correct answer)
- Lateral decubitus with legs extended
Correct answer: Prone with knee slightly flexed
The SSV is best evaluated with the patient prone and the knee slightly flexed, which relaxes the popliteal fossa and improves access to the saphenopopliteal junction.
VT DVT & Venous Reflux Assessment 3
May-Thurner syndrome results in DVT risk due to compression of which vessel?