Venography, Lower Extremity Studies


Venography, Lower Extremity Studies

Synonym/acronym: Lower limb venography, phlebography, venogram.

Common use

To visualize and assess the venous vasculature in the lower extremities related to diagnosis of deep vein thrombosis and congenital anomalies.

Area of application

Veins of the lower extremities.

Contrast

IV iodine based.

Description

Venography allows x-ray visualization of the venous vasculature system of the extremities after injection of an iodinated contrast medium. Lower extremity studies identify and locate thrombi within the venous system of the lower limbs. After injection of the contrast medium, x-ray images are taken at timed intervals. Usually both extremities are studied, and the unaffected side is used for comparison with the side suspected of having deep vein thrombosis (DVT) or other venous abnormalities, such as congenital malformations or incompetent valves. Thrombus formation usually occurs in the deep calf veins and at the venous junction and its valves. If DVT is not treated, it can lead to femoral and iliac venous occlusion, or the thrombus can become an embolus, causing a pulmonary embolism. Venography is accurate for identifying thrombi in veins below the knee.

This procedure is contraindicated for

    • high alert Patients who are pregnant or suspected of being pregnant, unless the potential benefits of a procedure using radiation far outweigh the risk of radiation exposure to the fetus and mother.
    • high alert Patients with conditions associated with adverse reactions to contrast medium (e.g., asthma, food allergies, or allergy to contrast medium). Although patients are still asked specifically if they have a known allergy to iodine or shellfish, it has been well established that the reaction is not to iodine, in fact an actual iodine allergy would be very problematic because iodine is required for the production of thyroid hormones. In the case of shellfish, the reaction is to a muscle protein called tropomyosin; in the case of iodinated contrast medium, the reaction is to the noniodinated part of the contrast molecule. Patients with a known hypersensitivity to the medium may benefit from premedication with corticosteroids and diphenhydramine; the use of nonionic contrast or an alternative noncontrast imaging study, if available, may be considered for patients who have severe asthma or who have experienced moderate to severe reactions to ionic contrast medium.
    • high alert Patients with conditions associated with preexisting renal insufficiency (e.g., renal failure, single kidney transplant, nephrectomy, diabetes, multiple myeloma, treatment with aminoglycosides and NSAIDs) because iodinated contrast is nephrotoxic.
    • high alert Elderly and compromised patients who are chronically dehydrated before the test, because of their risk of contrast-induced renal failure.
    • high alert Patients with bleeding disorders because the puncture site may not stop bleeding.
    • high alert Patients with severe edema of the legs in whom venous access is not possible.

Indications

  • Assess deep vein valvular competence
  • Confirm a diagnosis of DVT
  • Determine the cause of extremity swelling or pain
  • Determine the source of emboli when pulmonary embolism is suspected or diagnosed
  • Distinguish clot formation from venous obstruction
  • Evaluate congenital venous malformations
  • Locate a vein for arterial bypass graft surgery

Potential diagnosis

Normal findings

  • No obstruction to flow and no filling defects after injection of radiopaque contrast medium; steady opacification of superficial and deep vasculature with no filling defects

Abnormal findings related to

  • Deep vein valvular incompetence
  • DVT
  • Pulmonary embolism
  • Venous obstruction

Critical findings

  • DVT
  • Pulmonary embolism

  • 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

  • Factors that may impair clear imaging

    • Metallic objects (e.g., jewelry, body rings) within the examination field, which may inhibit organ visualization and cause unclear images.
    • Movement of the leg being tested, excessive tourniquet constriction, insufficient injection of contrast medium, and delay between injection and the x-ray.
    • Severe edema of the legs, making venous access impossible.

  • Other considerations

    • Improper injection of the contrast medium that allows it to seep deep into the muscle tissue.
    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status, may interfere with the test results.
    • Consultation with a HCP should occur before the procedure for radiation safety concerns regarding younger patients or patients who are lactating. Pediatric & Geriatric Imaging Children and geriatric patients are at risk for receiving a higher radiation dose than necessary if settings are not adjusted for their small size. Pediatric Imaging Information on the Image Gently Campaign can be found at the Alliance for Radiation Safety in Pediatric Imaging (www.pedrad.org/associations/5364/ig/).
    • Risks associated with radiation overexposure can result from frequent x-ray procedures. Personnel in the room with the patient should wear a protective lead apron, stand behind a shield, or leave the area while the examination is being done. Personnel working in the examination area should wear badges to record their level of radiation exposure.

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 in the lower extremities.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex, anesthetics, contrast medium, or sedatives.
  • Note any recent procedures that can interfere with test results, including examinations using barium- or iodine-based contrast medium.
  • Obtain a history of the patient’s cardiovascular and respiratory systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including anticoagulants, aspirin and other salicylates, herbs, nutritional supplements, and nutraceuticals, especially those known to affect coagulation (see Effects of Natural Products on Laboratory Values online at DavisPlus). Such products should be discontinued by medical direction for the appropriate number of days prior to a surgical procedure. Note the last time and dose of medication taken.
  • Note that if iodinated contrast medium is scheduled to be used in patients receiving metformin (Glucophage) for non-insulin-dependent (type 2) diabetes, the drug should be discontinued on the day of the test and continue to be withheld for 48 hr after the test. Iodinated contrast can temporarily impair kidney function, and failure to withhold metformin may indirectly result in drug-induced lactic acidosis, a dangerous and sometimes fatal side effect of metformin related to renal impairment that does not support sufficient excretion of metformin.
  • Review the procedure with the patient. Address concerns about pain and explain to the patient that there may be moments of discomfort and some pain experienced during the procedure. Inform the patient that the procedure is usually performed in a radiology or vascular suite by an HCP, 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.
  • Explain that an IV line may be inserted to allow infusion of IV fluids such as normal saline, anesthetics, sedatives, or emergency medications. Explain that the contrast medium will be injected, by catheter, at a separate site from the IV line.
  • Inform the patient that a burning and flushing sensation may be felt throughout the body during injection of the contrast medium. After injection of the contrast medium, the patient may experience an urge to cough, flushing, nausea, or a salty or metallic taste.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined prior to the procedure.
  • Instruct the patient to fast and restrict fluids for 8 hr prior to the procedure. Protocols may vary among facilities.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.
  • This procedure may be terminated if chest pain, severe cardiac arrhythmias, or signs of a cerebrovascular accident occur.

Intratest

  • Potential complications:

  • Complications include allergic reaction to the contrast medium, venous thrombophlebitis that is caused by contrast, venous embolism related to dislodgement of a deep-vein clot, and cellulitis or pain related to infiltration at the injection site.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure the patient has complied with dietary, fluid, and medication restrictions for 8 hr prior to the procedure.
  • Ensure the patient has removed all external metallic objects from the area to be examined prior to the procedure.
  • Administer ordered prophylactic steroids or antihistamines before the procedure if the patient has a history of allergic reactions to any substance or drug. Use nonionic contrast medium for the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Have emergency equipment readily available.
  • Instruct the patient to void prior to the procedure and to 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.
  • Record baseline vital signs, and continue to monitor throughout the procedure. Protocols may vary among facilities.
  • Establish an IV fluid line for the injection of saline, sedatives, or emergency medications.
  • Administer an antianxiety agent, as ordered, if the patient has claustrophobia. Administer a sedative to a child or to an uncooperative adult, as ordered.
  • Place electrocardiographic electrodes on the patient for cardiac monitoring. Establish baseline rhythm; determine if the patient has ventricular arrhythmias.
  • Using a pen, mark the site of the patient’s peripheral pulses before venography; this allows for quicker and more consistent assessment of the pulses after the procedure.
  • Place the patient in the supine position on an examination table. Cleanse the selected area, and cover with a sterile drape.
  • A local anesthetic is injected at the site, and a small incision is made or a needle inserted.
  • The contrast medium is injected, and a rapid series of images is taken during and after the filling of the vessels to be examined.
  • Instruct the patient to inhale deeply and hold his or her breath while the x-ray images are taken, and then to exhale.
  • Instruct the patient to take slow, deep breaths if nausea occurs during the procedure.
  • Monitor the patient for complications related to the procedure (e.g., allergic reaction, anaphylaxis, bronchospasm).
  • The needle or catheter is removed, and a pressure dressing is applied over the puncture site.
  • Observe/assess the needle/catheter insertion site for bleeding, inflammation, or hematoma formation.

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.
  • Instruct the patient to resume diet, fluids, and medications, as directed by the HCP. Renal function should be assessed before metformin is resumed.
  • Monitor vital signs and neurological status every 15 min for 1 hr, then every 2 hr for 4 hr, and then as ordered by the HCP. Take temperature every 4 hr for 24 hr. Monitor intake and output at least every 8 hr. Compare with baseline values. Notify the HCP if temperature is elevated. Protocols may vary among facilities.
  • Observe for delayed allergic reactions, such as rash, urticaria, tachycardia, hyperpnea, hypertension, palpitations, nausea, or vomiting.
  • Instruct the patient to immediately report symptoms such as fast heart rate, difficulty breathing, skin rash, itching, chest pain, persistent right shoulder pain, or abdominal pain. Immediately report symptoms to the appropriate HCP.
  • Assess extremities for signs of ischemia or absence of distal pulse caused by a catheter-induced thrombus.
  • Instruct the patient in the care and assessment of the site.
  • Instruct the patient to apply cold compresses to the puncture site as needed to reduce discomfort or edema.
  • Instruct the patient to maintain bed rest for 4 to 6 hr after the procedure or as ordered.
  • Recognize anxiety related to test results, and be supportive of perceived loss of independent function. 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.
  • 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 gradient, angiography pulmonary, antibodies anticardiolipin, antithrombin III, blood gases, CT angiography, d-dimer, FDP, lactic acid, lung perfusion scan, lung ventilation scan, MRA, MRI abdomen, MRI venography, plethysmography, PT/INR, renogram, US peripheral Doppler, and US venous Doppler extremity studies.
  • Refer to the Cardiovascular and Respiratory systems tables at the end of the book for related tests by body system.