If the results of a CT scan or lumbar puncture confirm you've had a subarachnoid haemorrhage, you'll usually be referred to a specialist neuroscience unit.
Further tests are usually needed to help plan treatment, which may include either:
- computed tomography angiography (CTA) – using a CT scan
- magnetic resonance angiography (MRA) – using an MRI scan
Both of these tests are carried out in the same way as a CT scan. But a special dye is injected into a vein (usually in your arm or hand) to highlight your blood vessels and tissues.
Occasionally, an angiogram may be needed. This 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.
Read more about angiography.