What Is a Venogram?

Medically Reviewed by Jennifer Robinson, MD on February 25, 2024
3 min read

A venogram is a test done by injecting contrast dye into your veins. After the dye is in your veins, your doctor will use a type of X-ray testing called a fluoroscopy to image your veins, typically in your legs. Venograms help to detect issues in your veins and can show where you may have clotting or clogging.

They can help diagnose different conditions, but they can also expose you to trace amounts of radiation.

Venogram tests are usually used to:

  • Test the function of a vein or group of veins
  • Find clotting or blockage in veins 
  • Investigate varicose veins before further treatment 
  • Identify veins suitable for bypass surgeries or dialysis
  • Help to put a stent or other medical device into a vein 
  • Figure out how to treat damaged veins

You can get a venogram in the following ways:

  • Ascending venography. This test is done if you might have deep vein thrombosis (a type of vein clotting) and can be used to locate the thrombosis. 
  • Descending venography. This is a test to see how well your deep vein valves work. 
  • Venography of the upper extremities. If your doctor thinks that you may have a blockage, clot, or vein problem in your neck or armpit, they may order this test. 
  • Venacavography. This is a test that images your inferior or superior vena cava. These veins carry blood to your heart. Your doctor will be able to look at blockages and other issues with this test. 

A venogram is a type of X-ray. X-rays use radiation to map out your bones and organs. X-rays are the oldest type of imaging test.

To prepare for your venogram, make sure you do the following:

  • Bring your letter of referral from your doctor to the specialist performing this test.
  • Come to your venogram dressed in loose and comfortable clothing.
  • Avoid wearing jewelry.

The venogram procedure will vary depending on where and what you are testing. If you are getting a lower leg venogram, you might expect:

  • You will be given a gown to wear during the procedure.
  • Your doctor will most likely mark with a pen where they want to check your pulse after the test. 
  • You will lay on a table. 
  • Your doctor will clean your foot and insert an IV into a vein on it. 
  • You will be injected with the contrast dye. 
  • X-rays of the dye moving into your legs will be taken.
  • Depending on your situation, your doctor may tie a tourniquet to your leg to slow down the flow of your blood. 
  • When the test is over, your doctor will take out your IV and remove the needle in your vein. 
  • Any open puncture marks from the procedure will be covered. 

You will most likely feel a flushing sensation, headaches, or nausea when the dye is first injected into you. These are normal and should go away quite quickly. However, if you start to feel itchy, have trouble breathing, or notice hives, immediately let your doctor know.

During venogram recovery after the procedure, you will be monitored. A team will keep tabs on your heart rate, breathing, and blood pressure. They will measure your pulse, temperature, and feeling of your legs. Make sure to drink fluids to help flush out the dye from the venogram. Some signs that you may need further medical attention include:

  • A fever 
  • Pain at the injection site
  • Swelling at the injection site
  • Bleeding or fluid buildup in the injection site

Like all X-rays, venograms use trace amounts of radiation that involve some risk. This is especially true if you are pregnant or might be pregnant, as radiation can cause birth defects. 

The biggest risk of a venogram is that you may have an allergy to the dye. Be sure to let your doctor know if you are sensitive to any sort of medication, dyes, or iodine. Additionally, let them know if you have any kidney issues, bleeding disorders, or if you are taking any blood thinners.

Venograms take 30 to 90 minutes to complete. After the test is finished, your doctor will evaluate the test results and speak to you about them. You might need to have a follow-up test to get additional images or double-check a previous finding.