Lung VQ scan — Patient information · Ruqelo Health
Radiology·Radiology
Lung VQ scan
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Educational summary — not medical advice. Discuss with your healthcare provider.
Informed by recognized medical guidance
Overview
A lung VQ (ventilation-perfusion) scan is a safe imaging test that looks at how air and blood flow through your lungs. It uses two tiny, safe amounts of radioactive material – one you breathe in and one given through a vein. The scan can help doctors find blood clots in the lungs (pulmonary embolism) or other problems with lung function.
Key facts
The test has two parts: breathing in a gas (ventilation) and an injection (perfusion).
It is painless and usually takes about 30–45 minutes.
The amount of radiation is very low and leaves your body quickly.
You can eat, drink, and take your normal medicines before the test unless your doctor tells you otherwise.
Questions about this article
Yes, VQ scans are a common and reliable test used worldwide, especially when a CT scan is not suitable – for example, in people with kidney problems or allergies to CT dye.
The scan is done for people who have symptoms that could be from a blood clot in the lung, such as sudden shortness of breath, chest pain, or coughing up blood. It is also used to check lung function before certain surgeries.
Symptoms
Call emergency services immediately if you notice:
Sudden severe shortness of breath or trouble breathing
Chest pain that is crushing, tight, or feels like a heavy weight
Coughing up a lot of blood or suddenly fainting
Blue or gray skin, lips, or fingernails (call your local emergency number immediately)
See a doctor urgently (same day) if you notice:
⚠Mild to moderate shortness of breath that lasts more than a few minutes
⚠Chest pain that comes and goes but doesn't feel severe
⚠Coughing up small streaks of blood
⚠A known risk for blood clots (like recent surgery or travel) with new breathing symptoms
Common symptoms
Sudden shortness of breath that comes on quickly
Sharp chest pain that gets worse when you breathe deeply or cough
Coughing up blood or pink frothy mucus
Rapid heartbeat or feeling like your heart is racing
Feeling lightheaded, dizzy, or passing out
Symptoms in children
Breathing faster than normal
Paleness or blue tint to lips or skin
Complaints of chest pain or tightness
Being unusually tired or irritable
Symptoms in older adults
Sudden confusion or feeling faint
Shortness of breath with little effort
A rapid or irregular heartbeat
Small amounts of blood in sputum (spit)
Causes
Main causes
The VQ scan itself is a test, not a disease. It is done to look for the cause of breathing symptoms – most often a blood clot (pulmonary embolism) that traveled from a leg vein.
Other causes of abnormal VQ scan results can include lung diseases like COPD, pneumonia, or a collapsed lung.
Risk factors
Prolonged immobility (long flights, bed rest)
Recent surgery or major injury (especially hip or leg)
Cancer or cancer treatment
Pregnancy or recent childbirth
Being over 60 years old
Smoking or obesity
A history of blood clots or a family member who had them
When to see a doctor
See a doctor urgently if:
Any sudden or severe breathing trouble – call your local emergency number right away.
Chest pain that feels like pressure or squeezing.
Coughing up a significant amount of blood.
Book a routine appointment if:
If you have mild but persistent shortness of breath, chest discomfort, or unexplained coughing – see your doctor within a few days.
If you have a known risk factor for blood clots and are worried about your lung health.
Follow-up after a VQ scan to discuss results and next steps.
A VQ scan is a straightforward, well-tolerated test. Most people go home the same day. It does not hurt, and the radioactive material leaves your body naturally within hours.
Diagnosis
A VQ scan is one of the main ways doctors diagnose a pulmonary embolism when a CT scan is not safe or available. It is often done after a chest X-ray and blood tests suggest a clot. The scan shows areas of the lung that are getting air but not enough blood (a possible clot) or areas not getting air (other lung problems).
Tests that may be done
Ventilation scan – you breathe in a small amount of radioactive gas through a mask.
Perfusion scan – you receive an injection of radioactive material into a vein.
Chest X-ray (usually done before or after)
Blood test called D-dimer (to check for clot fragments)
What to expect at your appointment
You will lie on a table while a special camera takes pictures. First, you breathe normally through a mask for a few minutes. Then you get an injection in your arm. After that, more pictures are taken. You may need to hold your breath briefly. You can usually go back to normal activities right away. Drink plenty of water to help flush the radioactive material from your body.
Treatment
Treatment depends on what the VQ scan finds. If a blood clot is found, the main goal is to stop the clot from getting bigger and prevent new ones. If the scan is normal, no blood clot treatment is needed, and your doctor will look for other causes of your symptoms.
Self-care at home
Follow your doctor’s instructions about activity level – you may need to rest if a clot is confirmed.
Take all prescribed medicines exactly as directed.
Wear compression stockings if recommended to prevent leg clots.
Stay well hydrated and avoid prolonged sitting or lying still.
Medical treatments
If a blood clot is found, doctors typically use medicines that thin the blood (anticoagulants) to prevent the clot from growing and to lower the risk of new clots. Treatment often lasts for several months. In some cases, a filter may be placed in a large vein to catch clots. You may also receive oxygen if your blood oxygen level is low.
When is surgery considered?
Surgery is rarely needed for a pulmonary embolism. In very serious cases, a doctor may remove the clot using a thin tube (catheter) or perform open surgery. This is usually only done when medicines do not work or if the clot is life-threatening.
Living with this condition
After a VQ scan, most people can go back to their normal routine. If you are diagnosed with a blood clot, you will need to take blood-thinning medicine as prescribed and attend regular check-ups. Watch for signs of bleeding or worsening symptoms.
Lifestyle tips
Stay active with gentle movement – but avoid strenuous exercise if you have a clot until your doctor says it’s safe.
If you travel long distances, get up and walk every hour and wear compression stockings if advised.
Do not smoke – smoking increases your risk of blood clots.
Keep a healthy weight and manage other health conditions like high blood pressure.
Diet and exercise
Eat a balanced diet rich in fruits, vegetables, and whole grains. If you take blood thinners, ask your doctor about foods with vitamin K (like leafy greens) – you don’t need to avoid them, but keep your intake consistent. Gentle exercise like walking, swimming, or yoga can improve circulation and lung function after recovery.
Mental health and emotional wellbeing
Having a lung clot can be frightening, and waiting for test results may cause anxiety. It’s normal to feel worried or stressed. Talk to your doctor or a counselor if these feelings last. Many people recover fully and lead healthy lives.
Prevention
You can lower your risk of blood clots in the lungs by staying active, drinking enough water, and not smoking. If you have surgery or are on bed rest, your doctor may give you medicine or compression devices to prevent clots.
Vaccines
There is no vaccine to prevent blood clots. However, staying up to date with other vaccines (like flu and pneumonia) can help keep your lungs healthy and reduce your risk of lung infections that might make you less mobile.
Screening programmes
Routine screening for blood clots is not recommended for most people. If you have a high risk (for example, a family history of clots or a known clotting disorder), your doctor may suggest regular check-ups or preventive measures.
Complications
If left untreated
A blood clot in the lung can grow and block more blood vessels, causing severe breathing problems.
Untreated clots can lead to long-term lung damage (chronic thromboembolic pulmonary hypertension).
A large clot can be life-threatening if it stops blood flow to a big part of the lung.
Long-term outlook
The outlook after a VQ scan and any needed treatment is very good. Most people with a pulmonary embolism recover fully with proper care. With early treatment, the risk of serious complications is low. Many people return to their normal activities within weeks to months.
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Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 16, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.
