Catheter angiogram to check blood vessels

This information is about having a small (minor) procedure called a catheter angiogram.

An angiogram is a high quality (resolution) picture of your arteries (types of blood vessels). This picture is created using a colourless substance called a contrast agent and an X-ray machine.

The procedure allows a specialist doctor called an interventional radiologist (IR doctor) to diagnose conditions affecting your arteries.

We do the procedure in the interventional radiology department by putting a plastic tube called a catheter into an artery. The IR doctor guides the catheter inside the artery. They can reach any artery in the body through the groin or sometimes through the arm.

The aim of this information is to help answer some of your questions about having a catheter angiogram. It explains:

If you have any more questions or concerns about your procedure, please contact the interventional radiology (IR) department.

About a catheter angiogram

Arteries are blood vessels that carry blood away from your heart to the rest of your body. Various conditions can affect the arteries and lead to a narrowing or blockage. This can cause symptoms and sometimes serious complications, depending on the artery involved.

A catheter angiogram is a test that shows where any blockages are in your arteries and how severe they might be. Your doctor can then recommend suitable treatment.

Arteries go all around the body. By injecting a special substance called a contrast agent, we can clearly see the arteries on X-ray pictures.

We do most angiograms in CT or MRI scanners after injecting the contrast agent. In some cases, we cannot see the arteries clearly. For example, this may be because of metal implants. A catheter angiogram is a small (minor) procedure to get good quality pictures of your arteries.

What interventional radiologists do

Interventional radiologists (IR doctors) are specialists, who do minimally invasive, image-guided procedures on different parts of the body. They use different imaging machines, such as X-ray or fluoroscopic (continuous X-ray) guidance, to show them exactly where to go inside the body. This avoids the need for large surgical cuts (incisions).

Procedures done under X-ray or fluoroscopic guidance are very safe. This is because the IR doctors can clearly see important structures of the body in real time.

IR doctors work in a team with:

  • specialist IR nurses
  • radiographers, who operate the specialist X-ray equipment

The whole team looks after you during your catheter angiogram and recovery.

Benefits of the procedure

A catheter angiogram allows us to see your arteries clearly. This helps your doctor to decide which treatment is best for you.

Risks of the procedure

A catheter angiogram is a safe procedure. Serious complications are very rare. It is a short, day-case procedure. You do not usually need to stay in hospital overnight, unless there are other reasons for this. We monitor you for 4 hours after the procedure and you can then go home in most cases.

As with any medical procedure, there are some possible risks involved.

Allergic reaction

It is possible to have an allergic reaction to the contrast agent that makes your arteries show clearly on the X-rays. This is usually a mild reaction, such as a skin rash, that gets better on its own.

Sometimes, there can be a more serious reaction that the IR doctor needs to treat. It is important to tell your IR doctor or nurse if you:

  • have ever had a previous allergic reaction to the substance iodine
  • have any other allergies

If you are allergic to the contrast agent, other options are available.

Kidney issues

The iodine in the contrast agent can affect how the kidneys work if they are already damaged. 

We do a routine blood test before your catheter angiogram to check how your kidneys work. If they are damaged, the IR doctor may:

  • connect a drip and give you a bag of fluid into your veins (intravenously) before and after the procedure to keep you hydrated
  • use a harmless gas as the contrast agent

Bruising or bleeding

The IR doctor needs to make a tiny hole with a needle in your artery, usually at the groin. This hole is controlled by outside pressure or by using a closure device (like a plug for the hole) at the end of the procedure. A small bruise in the area is usually the only sign.

Sometimes, the artery continues to bleed. If this happens, you will need treatment to stop the bleeding. The IR doctor usually gives you the treatment. Very rarely, you may need surgery.

Radiation risks

During the procedure, you are exposed to X-rays. They are a type of radiation called ionising radiation. This may cause cancer many years or decades after you are exposed to it.

You might have some skin redness after the procedure that feels like sunburn. This is unlikely and we do not expect it to be permanent. The redness might be harder to notice on brown and black skin.

Interventional radiology (IR) is when we use medical imaging guidance to do minimally invasive procedures. The amount (dose) of radiation from these procedures is generally low. More complex procedures might involve a medium (moderate) dose of radiation.

The IR doctor and radiographer make sure that:

  • your radiation dose is kept as low as possible
  • the benefits of having X-rays during your procedure are greater than the radiation risks

Radiation and pregnancy

Radiation can be harmful for an unborn baby. If you are or think that you might be pregnant, it is important to tell a member of your medical team before the procedure. We cannot do any procedure that involves radiation if you are pregnant.
If you can become pregnant from sex, you need to use protection (contraception) from the first day of your period until your appointment. This means that you will not be pregnant when you have the procedure.

If the first day of your period has already passed, please contact the interventional radiology (IR) department. We can then give you another appointment within the first 10 days of your period. 

We ask you to sign a pregnancy declaration form before the procedure.

Other treatment options

Sometimes, we can do an angiogram without making a tiny hole in your artery using a needle. Instead, we can do CT or MRI scans. The procedure is then called a CTA or MRA, but these scans are not suitable for everyone.

A catheter angiogram is the best option if other tests like a CT, MRI or ultrasound scan have found a possible problem or their results are unclear.

Resource number: 0043/VER6
Last reviewed: March 2024
Next review due: March 2027

A list of sources is available on request.

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions or concerns about having a catheter angiogram, please contact the interventional radiology (IR) department.


We are open from Monday to Friday, 9am to 5pm.

If you feel that you need urgent medical attention or are worried about anything outside of working hours, you can:

  • contact our on-call vascular registrar (doctor) through the switchboard on 020 7188 7188
  • contact a GP
  • call 111 (which gives health information and advice from a specially trained nurse by phone 24 hours a day)
  • go to your nearest emergency department (A&E)

Pharmacy medicines helpline

If you have any questions or concerns about your medicines, please speak to the staff caring for you.

You can also contact our pharmacy medicines helpline.

Phone: 020 7188 8748, Monday to Friday, 9am to 5pm

Email: [email protected]

We aim to respond to emails within 2 working days.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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