12 Questions
What may result in a continuous flow pattern during Doppler venous study?
Thrombosis at the site of examination
What does the loss of affect on distal compression during Doppler venous study indicate?
Venous obstruction from compression site to transducer placement
When does reverse or retrograde flow occur during Doppler venous study?
Incompetent valves
Why is angle correction of the Doppler signal not necessary during venous duplex imaging?
It provides clinical information
What does pulsatile venous flow indicate in Doppler venous study?
Fluid overload
What is the purpose of compressions in the transverse view during a venous ultrasound?
To assess for deep vein thrombosis
What should be done to the Doppler sample volume during Doppler venous study to visualize low-velocity signals?
Increase the sample volume
What is the significance of distal augmentation during a venous ultrasound?
It demonstrates patency of the venous system
In which position should the patient be placed for a venous ultrasound to test the response to Valsalva's Maneuver?
Supine position
How does phasic flow differ from continuous flow in a venous ultrasound?
Phasic flow follows the respiratory pattern
What happens to the blood flow in veins during Valsalva's Maneuver in a normal response?
Increased velocities are seen after completing Valsalva
What is the characteristic of normal veins when compressed by a transducer during a venous ultrasound?
The vessel walls collapse with pressure
Study Notes
Patient Positioning
- Patient is positioned in supine position with the leg externally rotated and the knee slightly flexed.
- The bed or table should be in reverse Trendelenburg (head-elevated) position.
Transverse View
- Locate the veins and perform compression maneuver on 2D imaging.
- Normal veins: vessel walls collapse with light to moderate pressure by the transducer on the skin.
- Compressions are done 3cm to 4cm distance in the whole length.
Normal Doppler Signals
- Sagittal view is used.
- Spontaneous flow: flow occurs spontaneously with the patient at rest.
- Phasic flow: follows the respiratory pattern of the patient, with greater flow in lower extremity during expiration and decreased or cessation in flow during inspiration.
- Distal augmentation: manual compression of the extremity distal to the site of ultrasound examination increases or augments venous flow.
- Response to Valsalva's maneuver: normal deep inspiration followed by bearing down results in cessation of blood flow in veins, and increased velocities are seen after completing the Valsalva.
Abnormal Doppler Signals
- Loss of spontaneous flow: loss of respiratory phasicity, continuous flow pattern.
- Loss of effect on distal compression: no increase in venous flow and velocities.
- Reversal of flow during Valsalva or proximal compression: reverse or retrograde flow.
- Pulsatile venous flow: pulsatile flow rather than a smooth phasic flow pattern.
Important Points for Doppler Venous Study
- Doppler signals should be obtained from the longitudinal plane.
- Angle correction of the Doppler signal is not necessary during venous duplex imaging.
- Doppler sample volume may be increased to include the entire lumen of the vein, and the Doppler scale should be reduced to visualize the low-velocity venous Doppler signal.
Test your knowledge on performing lower extremity venous ultrasound using supine position with leg externally rotated. Learn how to locate veins, perform compression maneuvers, and interpret normal Doppler signals. Practice identifying normal vessel walls collapse and proper transducer pressure.
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