A venogram (venography) is a test that uses X-rays to create moving pictures of blood flow in your veins, particularly those in your legs and pelvis. Providers use this test to diagnose deep vein thrombosis when ultrasound images can’t provide needed information. Venography also helps guide surgical procedures that treat vein disease.


Illustration showing veins in a person’s legs along with a callout highlighting the presence of a blood clot in the thigh.
A venogram allows your healthcare provider to see blood moving through your veins. This can help diagnose conditions like deep vein thrombosis when other forms of testing, like ultrasound, aren’t adequate or possible.

What is a venogram?

A venogram (venography) is an X-ray procedure that shows blood flow in your veins. Its main purpose is to help healthcare providers diagnose and manage conditions that affect your veins, including blood clots.

In many cases, providers use vascular ultrasound to diagnose blood clots in your veins. However, venography is an alternative when ultrasound isn’t possible or doesn’t provide enough information. Providers also use venography to plan or guide venous disease treatments.

A venogram can evaluate blood flow in many different veins throughout your body. Providers typically use this test to look at veins in your:

  • Legs.
  • Pelvis.
  • Upper arms.

Unlike ultrasound, a venogram is invasive. That means a provider has to make a small needle puncture in your skin to access your veins. They inject a contrast dye into your veins so they can see your blood flow on the X-ray. Since the test uses X-ray technology, it involves a small dose of radiation.

Most people experience only mild discomfort during the test, and they have no serious side effects. However, this test may not be safe for some people, including those who are pregnant. It’s important to talk to your provider before having a venogram. Your provider will decide if the test is safe and appropriate for you.

The medical term “venography” refers to the testing process, while “venogram” refers to the resulting images. But people usually use “venogram” to mean both the test and the images.

When is this test performed?

Providers may order a venogram to:


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Test Details

How does a venogram work?

Venography uses X-rays (a form of radiation) to capture images of the inside of your body. Because veins normally don’t show up on an X-ray, your provider injects a contrast dye into your veins. This dye flows through your veins and makes them visible, allowing your provider to see blood clots or other blood flow problems.

While X-rays capture single moments in time, a single moment isn’t enough to show blood flow, which is a dynamic process. This means that providers need to see blood moving through your veins while it’s actually happening. So, to generate venograms, they use a technique called fluoroscopy. This method uses several pulses of an X-ray beam to take continuous, real-time images.

Think of the many individual pictures that come together to make an animation. That’s similar to how a venogram works. The moving pictures allow your provider to see your blood flow in action.

How do I prepare for the test?

Your provider will tell you how to prepare. They may ask you to fast (have no foods or drinks except water) for a few hours before the test. They’ll also let you know if you need to stop taking any medications.

Be sure to tell your provider:

  • Your current medications.
  • Any medical conditions you have, including allergies.
  • If you’ve ever had an allergic reaction to a contrast dye used in testing.
  • If you have kidney disease or problems with kidney function. Some contrast dyes may affect your kidneys.
  • If you’ve recently been sick.
  • If you’re pregnant or may be pregnant.

Before the test begins, you’ll need to remove jewelry and any metal objects that could disrupt the X-ray process. You should wear loose, comfortable clothing, but your provider may give you a gown to wear.

Are you awake for a venogram?

Yes, you’re typically awake for a venogram. Your provider may give you a sedative to help you relax.

What happens during a venogram?

A radiologic technologist performs this procedure. You can expect them to do the following steps:

  1. Ask you to lie down on an X-ray table. They may use safety straps to secure you to the table.
  2. Tell you which area of your body they’ll use to access your veins. It’s typically an area on your foot, groin or neck. The access site varies based on which veins your provider needs to see.
  3. Give you medication (local anesthetic) to numb the access site. They deliver this through a quick injection. It may feel like someone pinched your skin, but it shouldn’t hurt.
  4. Inject contrast dye into your veins through an intravenous line (IV). You may feel a bit of pressure in the area where your provider inserts the IV. You shouldn’t feel pain. You may feel warm or flushed as the contrast dye flows through your veins. This feeling will pass when the test ends.
  5. Reposition the table as needed. Your provider may adjust the angle or positioning of the X-ray table to get different views of your veins. The safety straps will keep you securely in place. If you feel uncomfortable at any point, tell your provider.
  6. Ask you to hold your breath. You may need to hold your breath for a few seconds, stay very still or perform the Valsalva maneuver. Your provider will explain exactly what to do. These breathing techniques can help your provider capture high-quality images.
  7. Run fluids through your IV line. This final step helps clear the contrast dye out of your veins.

There may be additional steps depending on the reason for your venography. For example, if venography helps guide a procedure (like thrombolytic therapy), your care team will perform other steps to give you the treatment you need. Your provider will explain what you should expect in your individual situation.

How long does a venogram take?

Venography typically takes 30 to 90 minutes.

What can I expect after the test?

Your provider will briefly monitor you for allergic reactions or other complications. They’ll tell you when you can go home. They may ask you to drink plenty of water for the next 24 hours to help flush the contrast dye out of your body.

What are the risks of a venogram?

Risks of venography include:

  • Exposure to a small dose of radiation.
  • Pain, bruising, bleeding or infection at the puncture site.
  • Allergic reaction to the contrast dye.
  • Kidney damage.
  • Deep vein thrombosis (rare).

Usually, the benefits of venography outweigh the possible risks. In some cases, venography may be too risky for you because of an underlying medical condition (like severe kidney disease). Discuss all possible risks with your provider before the procedure.

What are the side effects of a venogram?

You may feel sick to your stomach or a brief flushing sensation when your provider injects the contrast dye. That should quickly pass.

Rarely, people experience a delayed reaction to the contrast dye that begins hours or days later. This reaction is usually mild and can include:

  • Nausea and vomiting.
  • Headache.
  • Itchy skin.
  • A flushing sensation.
  • Mild rash or hives.

Moderate side effects may include:

Severe side effects include:

Call your healthcare provider right away if you have any delayed reactions. If your side effects are severe, seek emergency care. They could be signs of a serious allergic reaction that needs immediate treatment.


Results and Follow-Up

What type of results do you get?

Venography produces images that a radiologist will analyze. They’ll send a report to the provider who referred you for the test. Your provider will then talk with you about the results and explain what they mean. For example, the images may show you have a blood clot in a deep vein in your leg. Your provider will then recommend treatment based on the findings.

Sometimes, providers use venography for real-time imaging guidance during surgical procedures. In that case, your provider may not discuss results with you. Instead, they use the images in the moment to guide your treatment. They’ll let you know if any issues arise.

When should I call my healthcare provider?

Call your provider if you:

  • Have questions or concerns about why you need this test, how to prepare or what to expect.
  • Have side effects in the hours or days after the test.
  • Have questions about the results of your test or what’s next in your treatment plan.


Additional Common Questions

What is the difference between a venogram and an angiogram?

Both procedures show blood flow through your blood vessels using X-ray technology and contrast dye. The difference is that a venogram specifically evaluates your veins. An angiogram evaluates arteries or veins. Healthcare providers consider angiograms the gold standard for finding blockages in your arteries. They sometimes give you treatment (like angioplasty) at the same time.

Providers use venograms less often for diagnostic purposes, instead preferring other methods (like ultrasound) to find blockages in your veins.

A note from Cleveland Clinic

Medical testing can be stressful. You may worry about discomfort during the test or what the results will show. Be assured that your healthcare provider is there to answer your questions. Don’t hesitate to share your concerns and get the information you need to feel more comfortable with the process.

Medically Reviewed

Last reviewed on 04/26/2023.

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