Norm of Color Duplex Ultrasonography
Description of normal tissues, structure, and blood flow.
Usage of Color Duplex Ultrasonography
Noninvasive study that is performed to assess characteristics of blood flow including alterations of normal flow (e.g., sexual dysfunction), direction of flow, and presence of flow (e.g., thrombosis of upper extremity, vertebrobasilar ischemic disease). Tissue perfusion and tumor vascularization (e.g., acute pancreatitis) can also be assessed.
Description of Color Duplex Ultrasonography
Color duplex refers to the fact that this test presents on the screen a simultaneous display of Doppler information and the B-mode ultrasonographic image. High-frequency sound waves are passed over the structure, and a computer analyzes the time required for the impulse to be reflected back to a transducer. The computer converts this impulse to an electrical impulse that is viewed on the screen to create a three-dimensional picture of the structure, using color as a guide. The “Doppler” effect refers to a change in frequency that occurs when the sound wave is reflected from a moving object. The computer can display this change in frequency as sound or as color changes in the pictures, or both. Different colors are used to represent flow, one color toward the transducer and another color away from the transducer. Speed of flow can be indicated by changes in the color shade.
Professional Considerations of Color Duplex Ultrasonography
Consent form NOT required.
- Obtain ultrasonic gel or paste.
- The client is positioned on the bed or on an examination table to allow access to the structure that is to studied.
- The area that is to be studied is covered with the ultrasonic gel or paste, and the transducer is slowly passed over the area. The technician may use a longitudinal or a transverse approach in an attempt to obtain the best visualization of the structure.
- Video is obtained of the display for later review.
- The procedure should last less than 45 minutes depending on what structures are being visualized.
- Remove gel or paste from the skin.
- Return client to a comfortable position.
Client and Family Teaching
- You will not be allowed to eat or drink during the test.
- The test is painless and the ultrasonic waves cannot be felt.
- You must lie as still as possible during the test.
- The area that is being studied will be uncovered, but you will otherwise be covered.
Factors That Affect Results
- Abdominal fat can alter the intensity of a beam “looking” at abdominal structures.
- If the beams pass through substances such barium, gas, or food particles, the clarity of the image can be diminished.
- Client movement can affect the image clarity.