Subarachnoid Hemorrhage Workup Algorithm
Note: This document provides a structured summary of the Subarachnoid Hemorrhage (SAH) Workup Algorithm for educational and reference purposes. SAH is a medical emergency requiring rapid diagnosis and management. It is not a substitute for certified ACLS training and adherence to the latest guidelines published by the American Heart Association (AHA) or other relevant governing bodies. Always consult the most current official guidelines and local protocols.
Patient presents with sudden, severe headache (“worst headache of life”), often associated with nausea, vomiting, neck stiffness, photophobia, or altered mental status.
ABCs, vital signs, neurological assessment (GCS, focal deficits), IV access, labs (CBC, coagulation studies, electrolytes), manage blood pressure (avoid hypotension and excessive hypertension).
Rapidly obtain a non-contrast CT scan. This is the initial imaging modality of choice for suspected SAH.
Is there evidence of blood in the subarachnoid space on the CT scan?
Proceed to vascular imaging (CTA or MRA of the head and neck) to identify the source of bleeding, most commonly an aneurysm.
Perform CT Angiography (CTA) or MR Angiography (MRA). Digital Subtraction Angiography (DSA) may be needed if non-invasive imaging is negative or inconclusive, but suspicion remains high.
Does vascular imaging reveal an aneurysm or other source of bleeding?
Consult Neurosurgery/Interventional Neuroradiology. Plan for urgent securing of the aneurysm/source (coiling or clipping).
If suspicion remains high, consider Digital Subtraction Angiography (DSA). If DSA is also negative, consider other causes (e.g., perimesencephalic SAH).
Despite negative CT, does the clinical presentation (e.g., classic thunderclap headache) maintain a high suspicion for SAH?
Perform LP after 6-12 hours from symptom onset to look for xanthochromia (yellow discoloration of CSF due to bilirubin breakdown from blood). Check CSF cell count.
Is xanthochromia present or is there a high red blood cell count in the final tube?
Treat as SAH. Proceed to vascular imaging (CTA/MRA/DSA) to find the source.
SAH is unlikely. Consider other causes of headache and symptoms.
Evaluate for other causes of headache (e.g., migraine, tension headache, sinusitis, cervical spine issues) or neurological symptoms.
Consult Neurosurgery/Critical Care. Secure aneurysm/source. Manage BP, pain, anxiety. Nimodipine for vasospasm prevention. Monitor for complications (rebleeding, vasospasm, hydrocephalus, seizures).
Long-term follow-up, rehabilitation, management of risk factors.
