ABCD² stands for Age, Blood pressure, Clinical features, Duration, and Diabetes. It scores 0–7 and predicts the risk of stroke within 2 and 7 days after a TIA. It helps clinicians decide how urgently a TIA patient needs evaluation and whether hospital admission is warranted.

Low risk (0–3): 2-day stroke risk ~1%. Moderate risk (4–5): 2-day risk ~4.1%. High risk (6–7): 2-day risk ~8.1%. Higher-risk patients typically warrant urgent imaging, admission, and dual antiplatelet therapy.

Current guidelines recommend that high-risk patients (ABCD² ≥ 4) should be admitted or evaluated urgently (within 24 hours). Low-risk patients may be safely evaluated as outpatients with rapid access to imaging and specialist review within 24–48 hours. Clinical judgment should supplement the score.

Brain MRI with diffusion-weighted imaging (DWI), neurovascular imaging (CTA or MRA of head and neck), echocardiography, cardiac monitoring for atrial fibrillation, and standard labs. Dual antiplatelet therapy (aspirin + clopidogrel for 21 days) is recommended for high-risk TIA.