Bleeding in the brain - Diagnosing a subarachnoid haemorrhage

If it's thought that you have had a subarachnoid haemorrhage, you will need to have a brain scan in hospital as soon as possible.

A computerised tomography (CT) scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image.

In some cases, a subarachnoid haemorrhage is not picked up by a CT scan. If a CT scan is negative, but your symptoms strongly suggest you have had a haemorrhage, a test called a lumbar puncture will usually be carried out.

A lumbar puncture involves a needle being inserted into the lower part of the spine, so that a sample of the fluid that surrounds and supports the brain and spinal cord (cerebrospinal fluid) can be taken out. It will then be analysed for signs of bleeding.

Planning treatment

If the results of a CT scan or lumbar puncture confirm that you have had a subarachnoid haemorrhage, a test called an angiogram or arteriogram may be carried out to help plan treatment. This will usually be done in a specialist neuroscience unit.

An initial angiogram is usually done with a CT scan or an MRI scan, and this usually gives enough information to plan treatment. Occasionally, an angiogram may need to be done, which involves inserting a thin tube called a catheter into one of your blood vessels (usually in the groin). Local anaesthetic is used where the catheter is inserted, so you won't feel any pain.

Using a series of X-rays displayed on a monitor, the catheter is guided into the blood vessels in the neck that supply blood to the brain. Once in place, special dye is injected through the catheter and into the arteries of the brain. This dye casts a shadow on an X-ray, so the outline of the blood vessels can be seen and the exact position of the aneurysm can be identified.