Subarachnoid Hemorrhage (SAH) — Diagnostic & Management Pathway

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Thunderclap headache · non-contrast CT
   Non-contrast head CT result? (Sudden severe ('worst of life') headache ± neck stiffness, vomiting, altered consciousness, photophobia is highly suspicious for SAH. Immediate non-contrast head CT (sensitivity 98–100% within 6 h, declining thereafter).)
   • CT shows subarachnoid hemorrhage → SAH confirmed
   • CT negative but highly suspicious → Lumbar puncture
   • CT negative and low suspicion → CT negative · low suspicion
2. [End] CT negative · low suspicion
   Evaluate other headache causes (migraine, tension-type, reversible cerebral vasoconstriction syndrome, etc.), treat symptomatically with safety-net follow-up; repeat imaging immediately for any deterioration or new neurological signs.
3. [Decision] Lumbar puncture
   Does LP (≥6–12 h after onset) suggest SAH? (If CT is negative but suspicion is high, perform LP looking for xanthochromia and red cells that do not clear across tubes; CT + LP together approach 100% sensitivity.)
   • Positive (xanthochromia / red cells) → SAH confirmed
   • Negative → CT negative · low suspicion
4. [End] SAH confirmed
   1) Immediate oral/NG nimodipine 60 mg q4h × 21 days (the only proven measure to improve outcome and prevent delayed cerebral ischemia). 2) Vascular imaging (CTA; DSA is the gold standard) to localize the aneurysm → treat early: endovascular coiling (preferred when feasible) or surgical clipping. 3) Transfer to a high-volume center, ICU monitoring; before aneurysm treatment control BP (avoid too high/too low), analgesia/sedation, maintain euvolemia. 4) Hunt-Hess/WFNS grading; monitor and manage rebleeding, vasospasm/delayed ischemia (days 4–14), hydrocephalus (external ventricular drain), hyponatremia.

Source guidelines & references

• AHA/ASA Guideline for management of aneurysmal subarachnoid hemorrhage
• NICE NG228 Subarachnoid haemorrhage caused by a ruptured aneurysm. 2022

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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