Defibrination

Defibrination is the process of removing fibrin or preventing the formation of fibrin in blood, resulting in a fluid that remains non-clotting or defibrinated. Historically, defibrinated blood was produced by mechanical methods that disrupt fibrin formation or by physically removing fibrin from freshly drawn blood. In modern laboratory practice, defibrination typically involves combining anticoagulation with subsequent removal of fibrin strands by centrifugation and decanting, filtration, or enzymatic digestion of fibrin.

Methods used to achieve defibrination vary. Mechanical defibrination may involve stirring or whipping the sample to disrupt fibrin networks and separate them from the liquid. Chemical or enzymatic approaches can include the use of plasmin or other fibrinolytic agents to digest fibrin, or applying filtration to remove fibrin clots. Some workflows rely on anticoagulants to prevent clot formation during handling, followed by processing to produce a defibrinated product.

Applications and uses. Defibrinated blood is used in microbiology for the preparation of blood agar plates, where a fluid, non-clotting supplement supports even growth of bacteria. It has also been employed in historical transfusion experiments, in the preparation of certain sera and plasma fractions for research, and in some cell culture procedures where clotting would interfere with analysis or processing.

Limitations and safety. Defibrination alters the protein composition of blood and removes fibrinogen and other clotting factors, making it distinct from serum or standard plasma. Handling defibrinated animal or human blood carries biosafety considerations and potential variability between preparations, which can affect experimental outcomes. In modern clinical settings, defibrinated blood is largely of historical or specialized laboratory use, with serum or anticoagulated plasma serving contemporary needs.