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Thrombocytopenia: investigation

Essential points for quick revision.

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Escalate

Active major bleeding, new neurological or renal dysfunction with haemolysis, pregnancy hypertension with organ injury, suspected DIC, or a platelet fall with thrombosis after heparin requires immediate senior and haematology assessment. Review the blood film urgently for schistocytes and blasts. When immune TTP is plausible, send ADAMTS13 before plasma if feasible but begin the specialist treatment pathway without waiting for the result.

Synopsis

Confirm a genuine low platelet count, use film and clinical context to separate production, destruction, consumption and sequestration, and identify TTP, DIC, HIT and critical bleeding without delay.

  • Confirm that thrombocytopenia is real: EDTA-dependent platelet clumping, difficult sampling and platelet satellitism can produce a spuriously low automated count.
  • Repeat the count in a citrate or other validated alternative tube and inspect a blood film when clumping or an unexpected isolated result is reported.
  • First determine urgency from bleeding, physiology, neurological or renal features, pregnancy, sepsis, thrombosis and the direction and speed of count change.

Key red flags

TTP emergency

Thrombocytopenia plus microangiopathic haemolysis and neurological, renal or abdominal features requires immediate plasma-exchange service contact.

Investigation priorities

01
Repeat count and alternative-anticoagulant sampleFirst step

Confirm genuine thrombocytopenia and remove EDTA-related artefact.

Management branches

ConfirmationVerify the number without missing danger

An analyser reports a new low platelet count.

  1. Assess active bleeding, haemodynamics, neurology, kidneys, pregnancy, sepsis, thrombosis and recent heparin before repeating a clinically unexpected count.
  2. Request an urgent film and repeat in citrate or another validated tube if clumping is possible, while comparing the complete historical trajectory.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom