Hi,
CT (computerized tomography) scan
of the head will show a subarachnoid hemorrhage in more than 90%
of cases
of ruptured aneurysm. In the few cases that are not recognized by CT, the healthcare provider may consider performing a lumbar puncture (LP, or spinal tap) to identify blood in the cerebrospinal fluid that runs in the subarachnoid space.
If the CT or the LP reveals the presence of blood, angiography is performed to identify where the aneurysm is located and to plan treatment.