Coagulation laboratory tests

Clot retraction

Last author update: 1 June 2012
Last staff update: 14 September 2020

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PubMed Search: Clot retraction [title]

Jeremy C. Parsons, M.D.
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Table of Contents
Definition / general
Cite this page: Parsons JC. Clot retraction. website. Accessed June 5th, 2023.
Definition / general
  • Obsolete test
  • Evaluates how well platelets keep the clot adhered to the sides of specimen tube
  • Uses whole blood in red top tube
  • Examine clot at 1, 2, 4 and 24 hours for clot retraction
  • After clot forms, remaining 40 - 60% consists of serum and red blood cell "fall - out" from clot
  • Must have normal fibrinogen and hematocrit for test be accurate

  • Reduced clot formation:
    • Glanzmann thrombasthenia: reduced glycoprotein IIb / IIIa causes reduced platelet aggregation and clot retraction
    • DIC, hypofibrinogenemia, dysfibrinogenemia (small clot with increased red blood cell "fall - out")
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