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Information ⬇

Synonym/Acronym

Lower limb venography, phlebography, venogram.

Rationale

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

Patient Preparation

There are no activity restrictions unless by medical direction. Instruct the patient to fast and restrict fluids for 8 hr, or as ordered, prior to the procedure. Fasting may be ordered as a precaution against aspiration related to possible nausea and vomiting. The American Society of Anesthesiologists has fasting guidelines for risk levels according to patient status. More information can be located at www.asahq.org.

Note: Protocols regarding the use of iodinated contrast medium in patients with impaired kidney function and who are receiving metformin or drugs containing metformin for type 2 diabetes may vary by facility; the drug may be discontinued on the day of the test and continue to be withheld for 48 hr after the test. Kidney function should be assessed per facility protocol before use of metformin is resumed (e.g., Cr, eGFR, hydration or clinical assessment).

Regarding the patient’s risk for bleeding, the patient should be instructed to avoid taking natural products and medications with known anticoagulant, antiplatelet, or thrombolytic properties or to reduce dosage, as ordered, prior to the procedure. Number of days to withhold medication is dependent on the type of anticoagulant. Note the last time and dose of medication taken. Protocols may vary among facilities.

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.

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

Study type: X-ray, Special/Contrast; related body system: Circulatory system.

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 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. Noninvasive diagnostic imaging technologies (e.g., computed tomography [CT], magnetic resonance imaging [MRI], duplex ultrasound [US]) have replaced angiographic venography to a large extent.

Indications ⬆ ⬇

Interfering Factors ⬆ ⬇

Contraindications

Pregnancy is a general contraindication to procedures involving radiation.

Patients with conditions associated with adverse reactions to contrast medium (e.g., asthma, food allergies, or allergy to contrast medium). Although patients are asked specifically if they have a known allergy to iodine or shellfish (shellfish contain high levels of iodine), it has been well established that the reaction is not to iodine; an actual iodine allergy would be 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.

Patients with moderate to marked renal impairment (glomerular filtration rate less than 30 mL/min/1.73 m2), or with conditions associated with preexisting renal insufficiency (e.g., chronic kidney disease, single kidney transplant, nephrectomy, diabetes, multiple myeloma, treatment with aminoglycosides and NSAIDs), because iodinated contrast is nephrotoxic.

Patients with moderate to marked renal impairment (glomerular filtration rate less than 30 mL/min/1.73 m2) and who are also taking metformin, which may put them at risk for development of drug-induced lactic acidosis, a dangerous and sometimes fatal adverse effect of metformin (related to renal impairment that does not support sufficient excretion of metformin).

Patients who are chronically dehydrated before the test, especially older adults and patients whose health is already compromised, because of their risk of contrast-induced acute kidney injury.

Patients with bleeding disorders, because the puncture site may not stop bleeding.

Patients with severe edema of the legs in whom venous access is not possible.

Factors That May Alter the Results of the Study

  • 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.
  • 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 movement can produce blurred or otherwise unclear images.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Abnormal Findings Related to

  • Deep vein valvular incompetence
  • DVT
  • PE
  • Venous obstruction

Nursing Implications, Nursing Process, Clinical Judgement ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

  • Discuss how this procedure can assist in assessing the veins in the lower extremities.
  • Explain that the procedure takes about 30 to 60 min and is usually performed in a radiology or vascular suite.
  • Review the procedure with the patient.
  • Explain that pregnancy testing may be required.
  • Explain that prior to the procedure, laboratory testing may be required to determine the possibility of bleeding risk (coagulation testing) or to assess for impaired kidney function (serum Cr or eGFR) if use of iodinated contrast medium is anticipated.
  • Discuss how there may be moments of discomfort or pain when the IV line or catheter is inserted, allowing for infusion of fluids such as saline, anesthetics, sedatives, medications used in the procedure, or emergency medications.
  • Explain that contrast medium will be injected, by catheter, at a separate site from the IV line.
  • Advise that a burning and flushing sensation may be felt throughout the body during injection of the contrast medium and they may experience an urge to cough, flushing, nausea, or a salty or metallic taste.

Procedural Information

  • Policies regarding breastfeeding before and after an imaging procedure may vary among facilities. For additional information, see Appendix A: Patient Preparation and Specimen Collection, subsection: Potential Contraindications and Complications Associated With Diagnostic Procedures.
  • Baseline vital signs are recorded and monitored throughout the procedure.
  • Positioning for this procedure is in the supine position on an examination table with the selected area cleansed and covered with a sterile drape.
  • Electrocardiographic electrodes are placed for cardiac monitoring to establish a baseline rhythm and identify any ventricular dysrhythmias.
  • Peripheral pulses are marked with a pen before the venography, allowing for a quicker and more consistent assessment of the pulses after the procedure.
  • A local anesthetic is injected at the site, and a small incision is made or a needle inserted.
  • Contrast medium is injected, and a rapid series of images is taken during and after the filling of the vessels to be examined.
  • Instruction is given to inhale deeply, hold the breath while the x-ray images are taken, and then exhale.
  • The patient is advised to take slow, deep breaths if nausea occurs during the procedure.
  • An ordered antiemetic drug is administered, as needed. An emesis basin is available for use, as needed.
  • Once the study is completed, the needle or catheter is removed, and a pressure dressing is applied over the puncture site.

Potential Nursing Actions

Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.

Safety Considerations

  • Anticoagulants, aspirin, and other salicylates should be discontinued by medical direction for the appropriate number of days prior to a procedure where bleeding is a potential complication.

After the Study: Implementation & Evaluation Potential Nursing Actions

Avoiding Complications

  • Monitor the patient for complications related to the procedure.
  • Explain the importance of immediately reporting symptoms such as difficulty breathing, chest pain, fever, hyperpnea, hypertension, nausea, palpitations, pruritus, rash, tachycardia, urticaria, or vomiting.
  • Establishing an IV site and injection of contrast medium are invasive procedures that can cause rare complications. For additional information, see Appendix A: Patient Preparation and Specimen Collection, subsection: Potential Contraindications and Complications Associated With Diagnostic Procedures.
  • Additional complications include venous thrombophlebitis (that is caused by contrast), or venous embolism (related to dislodgement of a deep-vein clot).
  • Observe/assess the needle/catheter insertion site for bleeding, inflammation, or hematoma formation.
  • Administer ordered antihistamines or prophylactic steroids if the patient has an allergic reaction.

Treatment Considerations

  • Follow postprocedure vital sign and assessment protocol.
  • Resume diet, fluids, and medications, as directed by the HCP.
  • Kidney function should be assessed before metformin is resumed.
  • Instruct the patient to maintain bed rest for 4 to 6 hr after the procedure or as ordered.
  • Provide instructions on the care and assessment of the procedure site.
  • Explain the value of applying cold compresses to the puncture site as needed to reduce discomfort or edema.

Clinical Judgement

  • Consider how to overcome objections to DVT management including medications and temporary mobility limitations.

Follow-Up and Desired Outcomes

  • Understands that depending on the results of this procedure, additional testing may be needed to monitor disease progression and determine the need for a change in therapy.
  • Consider test results in relation to the patient’s symptoms, other tests performed, and lifestyle choices.