Subarachnoid haemorrhage

A guide for patients and carers

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Tests and investigations

CT scan

This is a special type of X-ray which takes pictures of the brain from different angles.

During the test you will be asked to lie on a scanner table while the scanner rotates around your head. It is a quick and painless examination.

The scan can show the location of the haemorrhage and any problems it might be causing.

Sometimes a dye is injected to show the blood vessels that might be the source of the bleeding.

Lumbar puncture

The brain and spinal cord, which extends from the brain down through the centre of your spine, are surrounded by clear liquid called cerebrospinal fluid (CSF). If there is bleeding into the subarachnoid space (the space that surrounds the brain and the spinal cord), there will be blood in the cerebrospinal fluid.

To take a sample of this fluid, a needle is passed between two vertebrae (spinal bones) at the lower end of the spine (the lumbar area) into the space containing the CSF. A small amount is drawn off in a syringe and sent to a laboratory for examination.

MRI scan

This scan produces pictures of the head and brain using strong magnetic fields and radio waves.

During the test, you will lie in a long tube. The scan is painless but, unfortunately, the scanner is very noisy.

The scan is able to show the blood vessels, the haemorrhage, and occasionally the aneurysm.

MRA scan

This is a special type of MRI scan to produce images of the blood vessels. It is quicker and less invasive than an angiogram (see below).

It is safe with a low risk of any problems or complications. A dye is injected into the back of your hand or into the crook of your elbow and flows around your bloodstream to highlight the blood vessels in your brain.

CTA scan

This is a special type of CT scan. It is similar to the MRA scan (see above), involving injections with a dye, but uses the CT scanner equipment.

Angiogram

An angiogram is an X-ray test used to produce pictures of blood vessels. A cerebral angiogram shows the blood vessels in your head and neck.

An angiogram is the key test for SAH.

After you have had a local anaesthetic, a very small, flexible tube (catheter) is inserted into the blood vessel in your groin (the femoral artery). This is passed through other blood vessels in your body until it reaches your neck. You will not feel it moving inside you.

The tube will be positioned into different blood vessels in the neck.

While this happens, you will receive injections of a special dye (called contrast agent) to produce more detail in the pictures. The injections might give you a general warm feeling, but this goes away quickly.

Before taking the first picture, the equipment around you will be moved into position. More dye is injected for further pictures. It is very important that you remain still throughout the procedure to ensure the pictures taken are as clear as possible.