Preparing for VQ scan

Overview

A VQ scan, short for ventilation-perfusion scan, is a test that looks at how well air and blood flow through your lungs. It uses a tiny amount of a radioactive substance (called a tracer) to create pictures. The test has two parts: one to see how air moves in and out of your lungs (ventilation), and another to see how blood flows through the tiny vessels in your lungs (perfusion). This helps doctors find blood clots in the lungs, called pulmonary embolism.

Yes, VQ scans are commonly done when doctors suspect a blood clot in the lungs. It is a safe and well-established test.

It is often recommended for people who have sudden shortness of breath, chest pain, or an unexplained drop in oxygen levels. It may also be used for people who cannot have a CT scan due to kidney problems or contrast dye allergy.

Symptoms

Common symptoms

• Sudden shortness of breath for no clear reason
• Sharp chest pain that gets worse when you breathe deeply
• Coughing up blood (even a small amount)
• Rapid heart rate or feeling lightheaded

Symptoms in children

• Children may have trouble describing their symptoms. Look for unusual tiredness, fast breathing, or pale skin.

Symptoms in older adults

• Older adults might have less obvious symptoms like confusion, general weakness, or fainting.

Causes

Main causes

• Blood clots that form in the legs (deep vein thrombosis) and travel to the lungs
• Injury or surgery that causes a blood clot to form
• Prolonged immobility, such as long bed rest or long flights

Risk factors

• Having had a blood clot before
• Cancer or cancer treatment
• Obesity
• Smoking
• Hormonal therapies like birth control pills or hormone replacement therapy
• Pregnancy or recent childbirth

When to see a doctor

See a doctor urgently if:

• If you have sudden chest pain or difficulty breathing, call your local emergency number immediately.

Book a routine appointment if:

• If you have symptoms like unexplained shortness of breath or chest discomfort that keeps coming and going
• If you have a leg that is swollen, warm, or painful (possible deep vein thrombosis)

Diagnosis

The VQ scan is one of the main tests used to diagnose pulmonary embolism. Your doctor will also take your medical history, do a physical exam, and may order blood tests (like D-dimer) or an ultrasound of your legs.

Tests that may be done

• Ventilation scan – you breathe in a harmless radioactive gas while a camera takes pictures
• Perfusion scan – you receive a small injection of radioactive tracer into a vein, and again pictures are taken
• Chest X-ray – sometimes done first to rule out other problems

What to expect at your appointment

You will lie on a table while a special camera moves close to your chest. For the ventilation part, you will breathe through a mask. For the perfusion part, you will get a small injection. The staff will guide you through each step. You can breathe normally. After the test, the radioactive tracer leaves your body naturally within a few hours.

Treatment

If a VQ scan shows a blood clot, treatment aims to stop the clot from getting bigger and prevent new clots. Treatment usually involves blood thinning medication (anticoagulants) taken by mouth or as injections. The length of treatment depends on the cause and your health.

Self-care at home

• Follow your doctor’s advice about taking medication exactly as prescribed
• Stay active but avoid strenuous activities until your doctor says it is safe
• Wear compression stockings if recommended for leg swelling

Medical treatments

Blood thinners (anticoagulants) are the mainstay. They help prevent existing clots from growing and new clots from forming. In some cases, stronger medications called clot-busters (thrombolytics) may be given through a vein for large clots that cause severe symptoms. Treatment is tailored to your individual health.

When is surgery considered?

Surgery is rarely needed. In life-threatening cases, a procedure called embolectomy may be done to remove the clot directly from the lung arteries. This is only for emergencies.

Living with this condition

If you have had a blood clot, you will need to take blood thinners for at least 3 to 6 months. You may need regular blood tests to check how well your blood is thinning. It is important to avoid injury and report any unusual bleeding to your doctor.

Lifestyle tips

• Take your medications exactly as prescribed
• Stay active with gentle exercise like walking
• Wear a medical alert bracelet or carry a card that says you are on blood thinners

Diet and exercise

Eat a balanced diet rich in fruits and vegetables. Be consistent with foods high in vitamin K (like leafy greens) if you are on certain blood thinners – your doctor will tell you if this matters. Avoid alcohol in excess. Start with light activities and gradually increase as you feel able.

Mental health and emotional wellbeing

Having a blood clot can be frightening. It is normal to feel anxious about another episode. Talk to your doctor or a mental health professional if these feelings persist. Support groups can also help.

Prevention

You can lower your risk by staying active, keeping a healthy weight, not smoking, and moving your legs during long trips. If you are at high risk, your doctor may recommend blood thinners as a preventive measure.

Screening programmes

No routine screening is recommended for the general public. If you have a family history of blood clots or other risk factors, talk to your doctor about your personal risk.

Complications

If left untreated

• A pulmonary embolism can be life-threatening if not treated promptly
• Untreated clots can cause long-term lung damage (pulmonary hypertension)
• Clots may also damage the right side of the heart over time

Long-term outlook

With prompt diagnosis and proper treatment, most people recover fully from a pulmonary embolism. The outlook is very good, especially when treatment starts early. Long-term risks are low, and many people return to their normal activities without lasting problems.

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