Strokes are usually diagnosed by doing physical tests and studying images of the brain produced during a scan. When you first arrive at hospital with a suspected stroke, the doctor will want to find out as much as they can about your symptoms. A number of tests can be done to confirm the diagnosis and determine the cause of the stroke. This may include:

• A blood test to find out your cholesterol and blood sugar level
• checking your pulse for an irregular heartbeat
• taking a blood pressure measurement

Brain scans

Even if the physical symptoms of a stroke are obvious, brain scans should also be done to determine:

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

Everyone with suspected stroke should have a brain scan within 1 hour of arriving at hospital. An early brain scan is especially important for people who:

• might benefit from medicine to clear blood clots (thrombolysis), such as alteplase or early anticoagulant treatment
• are already taking anticoagulant treatments
• have a lower level of consciousness

This is why a stroke is a medical emergency and you should call 999 when a stroke is suspected – there's 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, but uses multiple images to build up a more detailed 3-dimensional picture of your brain to help your doctor identify any problem areas.

During the scan, you may be given an injection of a special dye into one of the veins in your arm to help improve the clarity of the CT image and look at the blood vessels that supply the brain.

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 with complex symptoms, where the extent or location of the damage is unknown.

This type of scan shows brain tissue in greater detail, allowing smaller, or more unusually located, areas affected by a stroke to be identified.

Swallow tests

A swallow test is essential for anybody who has had a stroke, as the ability to swallow is often affected soon after having a stroke. When a person cannot swallow properly, there's a risk that food and drink may get into the windpipe and lungs, which can lead to chest infections such as pneumonia. This is called aspiration.

The test is simple. The person is given a few teaspoons of water to drink. If they can swallow this without choking and coughing, they'll be asked to swallow half a glass of water. If they have any difficulty swallowing, they'll be referred to a speech and language therapist for a more detailed assessment.