An operation is the only way to diagnose many brain tumours. A surgical biopsy is when a small portion of the tumour is removed during an operation, so that doctors can look at the tumour cells under a microscope.

The size, shape and other changes in the cells help doctors identify the type and grade of brain tumour.

For some brain tumours, a biopsy is the first part of an operation to remove all or part of your tumour.

For other brain tumours, you may just have a biopsy and then go on to have other treatments such as radiotherapy.

Standard biopsy

The biopsy should not take more than a couple of hours but you will probably have to stay at least one night at the hospital.

You will first have to have a CT or MRI scan so that your surgeon can plan the procedure.

You will be put under a local or general anaesthetic so that you do not feel anything.

The neurosurgeon will make a small hole (known as a burr hole) in your skull using a tiny drill. A very fine needle will be passed through the hole and into the tumour. A small section will be removed so that a pathologist can look at it under a microscope and determine what type of tumour it is.

Stereotactic biopsy

This is a special kind of biopsy. Images or pictures of the brain are taken first to guide the surgeons to the tumour.

Before the procedure, you will be fitted with a metal head frame. Several images are taken to get an accurate three-dimensional view. This enables the surgeons to place the needle in the exactly the right place. 

Neuroendoscopy

This test is done under general anaesthetic. A hole, 2cm wide, is drilled into the skull. A fine tube called a neuroendoscope is put into the hole and into the fluid-filled chambers of the brain (the ventricles). This test may be done to:

• Take a biopsy of a tumour that is in or near the ventricles;
• Take fluid samples for tests;
• Drain fluid if too much has built up and caused an increase in pressure (hydrocephalus).

Risk and consent

The thought of having a biopsy may seem quite scary. There is a risk with all surgery, however, a biopsy is actually quite safe and it will help the team of consultants to decide which treatment is best for you.

As biopsies are quite minor operations, the risks involved are very small. The main risk is bleeding or swelling afterwards. You may be given some steroid drugs to control any problems.

Consent

You will have to sign a consent form before any operation you have in hospital. Signing it means that you fully understand what will happen to you and that you are aware of any risks and side effects that the treatment may have. It is important to ask your doctor any questions you may have before you sign it.

Do I need a biopsy?

Doctors can often tell from the scans you have had what type of tumour you have. However, they cannot be completely sure of the type or grade of the tumour until they have looked at the cells it is made of under a microscope. 

Also, if your neurosurgeon is not sure that it is a tumour, they will often do a biopsy to make sure rather than put you through a big operation that is not needed.

In some cases a biopsy may not be needed. For instance, if the scans show the biggest part of the tumour can be taken out and it is in an area of the brain that can be reached quite easily, your surgeon may decide to take out all or part of the tumour without first doing a biopsy. This is so you do not have too many operations.

If your tumour is in a part of the brain that cannot be reached easily or is close to important parts of the brain, it may be quite risky to do a biopsy.

If the tumour is small, looks benign (non-cancerous), and does not seem to be causing any harm, the surgeon may prefer to leave it alone but keep an eye on it using scans to make sure it does not change. 

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