Ventilation perfusion scan

Overview

A ventilation perfusion (V/Q) scan is a safe imaging test that looks at how air and blood flow through your lungs. It helps doctors find blood clots in the lungs, called pulmonary embolism (PE).

Yes, a V/Q scan is a common test when a doctor suspects a blood clot in the lungs. It is used in many hospitals around the world.

Anyone with symptoms of a blood clot in the lungs, such as sudden shortness of breath or chest pain, may be offered this scan. It is also used for people who cannot have a CT scan.

Symptoms

Common symptoms

• Sudden shortness of breath
• Sharp chest pain that gets worse when you breathe deeply or cough
• Coughing up blood

Symptoms in children

• Children may have similar symptoms, but they might also seem unusually tired or irritable.
• They might refuse to eat or play.

Symptoms in older adults

• Older adults may not have typical chest pain. Instead, they might feel confused, lightheaded, or have a rapid heart rate.
• They may also have a sudden drop in blood pressure.

Causes

Main causes

• A blood clot that travels to the lungs (pulmonary embolism) is the most common reason for a V/Q scan.
• Less often, the scan is used to check lung function in people with chronic lung disease.

Risk factors

• Recent surgery, especially on the hips, knees, or abdomen
• Prolonged sitting (like a long flight or car ride)
• Cancer and its treatment
• Pregnancy or recent childbirth
• Being overweight or having varicose veins

When to see a doctor

See a doctor urgently if:

• If you suddenly have trouble breathing or sharp chest pain, call your local emergency number immediately.
• If you cough up blood, seek emergency care.

Book a routine appointment if:

• If you have mild shortness of breath or chest pain that comes and goes, make an appointment with your GP (family doctor) as soon as possible.

Diagnosis

A V/Q scan is done in a hospital's nuclear medicine department. First, you breathe in a harmless radioactive gas (ventilation part). Then you receive an injection of a different radioactive substance (perfusion part). A special camera takes pictures of your lungs.

Tests that may be done

• Ventilation perfusion (V/Q) scan
• Sometimes a CT scan of the chest (CT pulmonary angiogram) is done instead, but a V/Q scan is used if CT is not safe for you.

What to expect at your appointment

You will lie on a table while a camera moves over your chest. You will be asked to breathe normally. The scan is painless. After the test, you can go back to your normal activities. The radiation exposure is very low.

Treatment

If the scan finds a blood clot, treatment aims to stop the clot from getting bigger and prevent new clots. This usually involves medicines called blood thinners (anticoagulants).

Self-care at home

• Stay as active as your doctor allows. Gentle walking helps blood flow.
• Drink plenty of water to stay hydrated.
• Stop smoking – it raises your risk of clots.
• Avoid sitting for long periods. Get up and move every hour.

Medical treatments

Blood thinners are given as pills or injections. They make it harder for your blood to clot, which reduces the risk of further clots. You may need to take them for several months or longer, depending on the cause. Your doctor will monitor you with regular blood tests.

When is surgery considered?

In very rare, severe cases, surgery may be needed to remove a large clot (embolectomy). This is only done if medicines do not work or cannot be used.

Living with this condition

After a blood clot, you will likely take blood thinners and have regular check-ups. You will need to watch for signs of bleeding (like easy bruising, nosebleeds, or blood in urine) and contact your doctor if these occur.

Lifestyle tips

• Wear compression stockings if your doctor suggests them to improve blood flow in your legs.
• Move your legs regularly, especially during long trips.
• Maintain a healthy weight.

Diet and exercise

Eat a balanced diet rich in fruits, vegetables, and whole grains. Stay active with moderate exercise like walking, swimming, or cycling. Avoid high-impact sports if you are on blood thinners, as you may bruise easily.

Mental health and emotional wellbeing

Having a blood clot can be frightening. You may feel anxious about it happening again. It is normal to feel this way. Talk to your doctor or a counsellor if you need support.

Prevention

Many blood clots can be prevented. Stay active, drink plenty of fluids, and avoid sitting for long periods. If you are at high risk (for example, after surgery), your doctor may give you blood thinners or compression devices.

Complications

If left untreated

• A blood clot can damage the lungs and reduce oxygen levels in the body.
• It can lead to long-term breathing problems, called chronic thromboembolic pulmonary hypertension.
• In severe cases, an untreated clot can be life-threatening.

Long-term outlook

With prompt treatment, most people recover fully from a pulmonary embolism. Blood thinners are very effective at preventing new clots. Your outlook is excellent if you follow your treatment plan and stay active.

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