Bleeding time (BT)

What it measures

Measures how long a small standard skin cut takes to stop bleeding. It reflects platelet function and vessel wall response, but is now rarely used because it is poorly reproducible.

Specimen and preparation

• Specimen: In-vivo test on the forearm or earlobe
• Tube: Other top
• Preparation: Stop aspirin and NSAIDs for 7 days if clinically safe. Avoid visible veins and scarring areas.

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Thrombocytopenia
• Platelet function disorders (Glanzmann, Bernard-Soulier)
• von Willebrand disease
• Aspirin or NSAID use
• Uremia
• Vascular disorders (scurvy, Ehlers-Danlos)

Method

Ivy method (template incision with 40 mmHg cuff) or Duke method (earlobe puncture)

Good to know

Largely replaced by platelet function analyzers (PFA-100) and aggregation studies. Does not predict surgical bleeding.

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