If a brain abscess is suspected, the diagnosis can be confirmed using a brain scan.

An initial assessment will be made based on your physical symptoms and medical history, such as whether you have had a recent infection or a weakened immune system.

Blood tests can also be carried out to check for the presence of infection. A high level of white blood cells in your blood indicates the presence of a serious infection.

If you are referred to hospital for further tests, you may have either:

• a computerised tomography (CT) scan – which involves a series of X-rays to produce a detailed image of the inside of your body
• a magnetic resonance imaging (MRI) scan – which uses strong magnetic fields and radio waves to produce a detailed image of the inside of your body.

A CT scan can often detect the presence of the abscess and any associated swelling inside the brain.

A MRI scan can provide a more detailed image than a CT scan, so is sometimes used if the results of the CT scan are inconclusive. 

CT-guided aspiration

If an abscess is found, neurosurgeons (doctors who specialise in the treatment of the nervous system and brain) can use a CT scan to guide a needle to the site of the abscess and remove a sample of pus for further testing. This is known as CT-guided aspiration. The sample of pus should indicate the type of germ causing the abscess.

Treatment with broad-spectrum antibiotics will usually begin as soon as possible, even before a CT-guided aspiration is carried out, because it can be dangerous to wait for the results.

Broad-spectrum antibiotics can be used against a wide range of bacteria. They will be used before a specific diagnosis is made, because there is a high chance they will be effective if the infection is caused by bacteria.

If the test reveals the abscess is caused by a fungus, the treatment plan can be changed and antifungal medication given.

Read more information about treating a brain abscess.