Skip to main content

Warning notification:Warning

Unfortunately, you are using an outdated browser. Please, upgrade your browser to improve your experience with HSE. The list of supported browsers:

  1. Chrome
  2. Edge
  3. FireFox
  4. Opera
  5. Safari

Diagnosis - Stroke

Strokes are usually diagnosed by doing physical tests and studying brain scans.

Tests may include:

  • blood tests to check your cholesterol and blood sugar levels
  • checking your pulse for an irregular heartbeat
  • monitoring your heart rhythm
  • checking your blood pressure
  • an ultrasound on your heart or neck vessels

Brain scans

Brain scans are also done to find:

  • if there is a blocked artery (ischaemic stroke) or burst blood vessel (haemorrhagic stroke)
  • which part of the brain has been affected
  • how severe the stroke is

An early brain scan is important for people who:

  • might need clot-busting drugs (thrombolysis) or a procedure to remove the blood clot 
  • need or are already on anticoagulant treatments (medicines that help prevent blood clots)
  • have a lower level of consciousness (when a person is awake but not responding normally)

Emergency action required: Call 999 or 112 and ask for an ambulance if:

  • you think someone is having a stroke

A stroke is a medical emergency. There is no time to wait for a GP appointment.

The 2 main types of scan used to assess the brain in people who have had a suspected stroke are:

  • a CT scan
  • an MRI scan

CT scans

A CT scan is like an x-ray. It gives a detailed picture of your brain to help your doctor identify any problem areas.

You may be given an injection of a special dye into a vein in your arm. This is to improve the CT image and look at the blood vessels that supply the brain.

A CT scan is usually able to show whether you've had an ischaemic stroke or a haemorrhagic stroke. A CT scan is quicker than an MRI scan. This can help you start treatment sooner.

MRI scans

An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of your body.

It's usually used in people where the extent or location of the damage is unknown. It's also used in people who have recovered from a transient ischaemic attack (TIA).

This type of scan shows more detail of the brain tissue.

It can check:

  • smaller or unusually located areas that may have been affected by a stroke
  • for micro-bleeds that happen because of leaky blood vessels

A special dye can be used to improve MRI scan images.

Swallow tests

The ability to swallow may be affected soon after having a stroke.

If the doctor or nurse thinks you have had a stroke, they'll arrange a swallow test. This test is often done by a stroke nurse or a speech and language therapist.

If you can't swallow properly, there's a risk that food and drink may get into the windpipe and lungs. This is called aspiration. This can lead to chest infections such as pneumonia.

You will be given a few teaspoons of water to drink. If you can swallow this without choking and coughing, you'll be asked to swallow half a glass of water.

If you have any difficulty swallowing, the doctor or nurse will refer you to the speech and language therapist for a more detailed assessment.

You usually won't be allowed to eat or drink normally until you've seen the speech and language therapist.

Fluids or food may need to be given either:

  • directly into a vein in your arm (intravenously)
  • by a tube placed through your nose down into your stomach (nasogastric tube or ‘NG’ tube)

Heart and blood vessel tests

Tests on the heart and blood vessels may be done to confirm what caused your stroke.

Carotid ultrasound

A carotid ultrasound scan can help show if there's any narrowing or blockages in the neck arteries leading to your brain.

An ultrasound scan involves using a small probe (transducer) to send high-frequency sound waves into your body. When these sound waves bounce back, they can be used to create an image of the inside of your body.

If a carotid ultrasound is needed, it will usually happen within 48 hours.


An echocardiogram may be done to produce images of your heart and check for any problems that could be related to your stroke.

This normally involves moving an ultrasound probe across your chest (transthoracic echocardiogram).

Another type of echocardiogram called a transoesophageal echocardiography (TOE) may sometimes be used. The probe is put in your throat (oesophagus) behind your heart. You are usually given medicine to make you drowsy so you are comfortable during this test.

Page last reviewed: 28 June 2023
Next review due: 28 June 2026