A 55-year-old woman came to the emergency depament with complaint of severe headache. She also mention that this is the worst headache of her life. What is the most appropriate initial test for diagnosis?

By the above clinical history, probable diagnosis is Subarachnoid haemorrhage. Subarachnoid haemorrhage Investigation of choice for initial diagnosis is a computed tomography (CT) of the head without intravenous (IV) contrast( NCCT). On NCCT, blood in the subarachnoid space would appear whiter compared to the surrounding brain tissue. It can also demonstrate significant mass effect and midline shift, factors that increase the severity of the underlying hemorrhage. Other investigations: - Lumbar puncture: Bloody CSF seen in - Trauma - HSV encephalopathy - SAH RBC lysis (inside the CSF) - Bilirubin - give yellowish tinge to CSF (Xanthochromic CSF) Stas as early as 6-12 hours after the bleed and peak: 48 hours - CT angiography/ four vessel conventional X-ray angiography- to identify any other aneurysm - Electrolytes: Hyponatremia due to natriuresis