Ultrasound, Venous Doppler, Extremity Studies

Ultrasound, Venous Doppler, Extremity Studies

Synonym/acronym: Venous duplex, venous sonogram, venous ultrasound.

Common use

To assess venous blood flow in the upper and lower extremities toward diagnosing disorders such as deep vein thrombosis, venous insufficiency, causation of pulmonary embolism, varicose veins, and monitor the effects of therapeutic interventions.

Area of application

Veins of the upper and lower extremities.

Contrast

Done without contrast.

Description

Ultrasound (US) procedures are diagnostic, noninvasive, and relatively inexpensive. They take a short time to complete, do not use radiation, and cause no harm to the patient. High-frequency sound waves of various intensities are delivered by a transducer, a flashlight-shaped device, pressed against the skin. The waves are bounced back off internal anatomical structures and fluids, converted to electrical energy, amplified by the transducer, and displayed as images on a monitor. US is often used as a diagnostic and therapeutic tool for guiding minimally invasive procedures such as needle biopsies and fluid aspiration. The contraindications and complications for biopsy and fluid aspiration are discussed in detail in the individual monographs.

Ultrasound (US) procedures are used to obtain information about the patency of the venous vasculature in the upper and lower extremities to identify narrowing or occlusions of the veins or arteries. In venous Doppler studies, the Doppler identifies moving red blood cells (RBCs) within the vein. The US beam is directed at the vein and through the Doppler transducer while the RBCs reflect the beam back to the transducer. The reflected sound waves or echoes are transformed by a computer into scans, graphs, or audible sounds. Blood flow direction, velocity, and the presence of flow disturbances can be readily assessed. The velocity of the blood flow is transformed as a “swishing” noise, audible through the audio speaker. If the vein is occluded, no swishing sound is heard. For diagnostic studies, the procedure is done bilaterally. The sound emitted by the equipment corresponds to the velocity of the blood flow through the vessel occurring with spontaneous respirations. Changes in these sounds during respirations indicate the possibility of abnormal venous flow secondary to occlusive disease; the absence of sound indicates complete obstruction. Compression with a transducer augments a vessel for evaluation of thrombosis. Noncompressibility of the vessel indicates a thrombosis. Plethysmography may be performed to determine the filling time of calf veins to diagnose thrombotic disorder of a major vein and to identify incompetent valves in the venous system. An additional method used to evaluate incompetent valves is the Valsalva technique combined with venous duplex imaging.

The ankle-brachial index (ABI) can also be assessed during this study. This noninvasive, simple comparison of blood pressure measurements in the arms and legs can be used to detect peripheral artery disease (PAD). A Doppler stethoscope is used to obtain the systolic pressure in either the dorsalis pedis or the posterior tibial artery. This ankle pressure is then divided by the highest brachial systolic pressure acquired after taking the blood pressure in both of the patient’s arms. This index should be greater than 1. When the index falls below 0.5, blood flow impairment is considered significant. Patients should be scheduled for a vascular consult for an abnormal ABI. Patients with diabetes or kidney disease, and some elderly patients, may have a falsely elevated ABI due to calcifications of the vessels in the ankle causing an increased systolic pressure. The ABI test approaches 95% accuracy in detecting PAD. However, a normal ABI value does not absolutely rule out the possibility of PAD for some individuals, and additional tests should be done to evaluate symptoms.

This procedure is contraindicated for

    N/A

Indications

  • Aid in the diagnosis of venous occlusion secondary to thrombosis or thrombophlebitis
  • Aid in the diagnosis of superficial thrombosis or deep vein thrombosis (DVT) leading to venous occlusion or obstruction, as evidenced by absence of venous flow, especially upon augmentation of the extremity; variations in flow during respirations; or failure of the veins to compress completely when the extremity is compressed
  • Detect chronic venous insufficiency, as evidenced by reverse blood flow indicating incompetent valves
  • Determine if further diagnostic procedures are needed to make or confirm a diagnosis
  • Determine the source of emboli when pulmonary embolism is suspected or diagnosed
  • Determine venous damage after trauma to the site
  • Differentiate between primary and secondary varicose veins
  • Evaluate the patency of the venous system in patients with a swollen, painful leg
  • Evaluate PVD
  • Monitor the effectiveness of therapeutic interventions

Potential diagnosis

Normal findings

  • Normal Doppler venous signal that occurs spontaneously with the patient’s respiration
  • Normal blood flow through the veins of the extremities with no evidence of vessel occlusion

Abnormal findings related to

  • Chronic venous insufficiency
  • Primary varicose veins
  • PVD
  • Recannulization in the area of an old thrombus
  • Secondary varicose veins
  • Superficial thrombosis or DVT
  • Venous narrowing or occlusion secondary to thrombosis or thrombophlebitis
  • Venous trauma

Critical findings

  • DVT

  • It is essential that a critical finding be communicated immediately to the requesting health-care provider (HCP). A listing of these findings varies among facilities.

  • Timely notification of a critical finding for lab or diagnostic studies is a role expectation of the professional nurse. Notification processes will vary among facilities. Upon receipt of the critical value the information should be read back to the caller to verify accuracy. Most policies require immediate notification of the primary HCP, Hospitalist, or on-call HCP. Reported information includes the patient’s name, unique identifiers, critical value, name of the person giving the report, and name of the person receiving the report. Documentation of notification should be made in the medical record with the name of the HCP notified, time and date of notification, and any orders received. Any delay in a timely report of a critical finding may require completion of a notification form with review by Risk Management.

Interfering factors

  • Patients with an open or draining lesion.

  • Factors that may impair clear imaging

    • Attenuation of the sound waves by bony structures, which can impair clear imaging of the right lobe of the vessels
    • Incorrect placement of the transducer over the desired test site; quality of the US study is very dependent upon the skill of the ultrasonographer
    • Metallic objects (e.g., jewelry, body rings) within the examination field, which may inhibit organ visualization and cause unclear images
    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status

  • Other considerations

    • Cigarette smoking, because nicotine can cause constriction of the peripheral vessels
    • Cold extremities, resulting in vasoconstriction that can cause inaccurate measurements
    • Occlusion proximal to the site being studied, which would affect blood flow to the area
    • An abnormally large or swollen leg, making sonic penetration difficult

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in assessing the veins.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s cardiovascular system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Report the presence of a lesion that is open or draining; maintain clean, dry dressing for the ulcer; protect the limb from trauma.
  • Note any recent procedures that can interfere with test results (i.e., barium procedures, surgery, or biopsy). There should be 24 hr between administration of barium- or iodine-based contrast medium and this test.
  • Endoscopic retrograde cholangiopancreatography, colonoscopy, and computed tomography of the abdomen, if ordered, should be scheduled after this procedure.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that some pain may be experienced during the test, and there may be moments of discomfort. Inform the patient that the procedure is performed in a US department by an HCP who specializes in this procedure, with support staff, and takes approximately 30 to 60 min.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure that the patient has removed all external metallic objects from the area to be examined prior to the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to void and change into the gown, robe, and foot coverings provided.
  • Instruct the patient to cooperate fully and to follow directions. Ask the patient to remain still throughout the procedure because movement produces unreliable results.
  • Place the patient in the supine position on an examination table; other positions may be used during the examination.
  • Expose the area of interest and drape the patient.
  • Conductive gel is applied to the skin, and a transducer is moved over the area to obtain images of the area of interest. Waveforms are visualized and recorded with variations in respirations. Images with and without compression are performed proximally or distally to an obstruction to obtain information about a venous occlusion or obstruction. The procedure can be performed for both arms and legs to obtain bilateral blood flow determination.
  • Do not place the transducer on an ulcer site when there is evidence of venous stasis or ulcer.
  • Ask the patient to breathe normally during the examination. If necessary for better organ visualization, ask the patient to inhale deeply and hold his or her breath.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • When the study is completed, remove the gel from the skin.
  • Instruct the patient to continue diet, fluids, and medications, as directed by the HCP.
  • Nutritional Considerations: Abnormal findings may be associated with cardiovascular disease. Nutritional therapy is recommended for the patient identified to be at risk for developing coronary artery disease (CAD) or for individuals who have specific risk factors and/or existing medical conditions (e.g., elevated LDL cholesterol levels, other lipid disorders, insulin-dependent diabetes, insulin resistance, or metabolic syndrome). Other changeable risk factors warranting patient education include strategies to encourage patients, especially those who are overweight and with high blood pressure, to safely decrease sodium intake, achieve a normal weight, ensure regular participation of moderate aerobic physical activity three to four times per week, eliminate tobacco use, and adhere to a heart-healthy diet. If triglycerides also are elevated, the patient should be advised to eliminate or reduce alcohol. The 2013 Guideline on Lifestyle Management to Reduce Cardiovascular Risk published by the American College of Cardiology (ACC) and the American Heart Association (AHA) in conjunction with the National Heart, Lung, and Blood Institute (NHLBI) recommends a “Mediterranean”-style diet rather than a low-fat diet. The new guideline emphasizes inclusion of vegetables, whole grains, fruits, low-fat dairy, nuts, legumes, and nontropical vegetable oils (e.g., olive, canola, peanut, sunflower, flaxseed) along with fish and lean poultry. A similar dietary pattern known as the Dietary Approaches to Stop Hypertension (DASH) diet makes additional recommendations for the reduction of dietary sodium. Both dietary styles emphasize a reduction in consumption of red meats, which are high in saturated fats and cholesterol, and other foods containing sugar, saturated fats, trans fats, and sodium.
  • Social and Cultural Considerations: Note that numerous studies point to the prevalence of excess body weight in American children and adolescents. Experts estimate that obesity is present in 25% of the population ages 6 to 11 yr. The medical, social, and emotional consequences of excess body weight are significant. Special attention should be given to instructing the child and caregiver regarding health risks and weight-control education.
  • Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American Heart Association (www.americanheart.org), the NHLBI (www.nhlbi.nih.gov), or the Legs for Life (www.legsforlife.org).
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be needed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include alveolar/arterial ratio, angiography pulmonary, blood gases, CBC platelet count, CT angiography, d-dimer, FDP, fibrinogen, lung perfusion scan, lung ventilation scan, MRI abdomen, MRI angiography, MRI venography, aPTT, plethysmography, PT/INR, US arterial Doppler lower and upper extremity studies, and venography lower extremities.
  • Refer to the Cardiovascular System table at the end of the book for related tests by body system.