Coagulation laboratory tests
Clot retraction

Topic Completed: 1 June 2012

Revised: 7 January 2019, last major update June 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Clot retraction [title]

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Table of Contents
Definition / general
Cite this page: Parsons J. Clot retraction. website. Accessed August 6th, 2020.
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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