Testing for Bethesda Units is performed to quantify the degree of inhibition for an individual factor when specific factor inhibitor has been diagnosed, and to follow the patient with a factor inhibitor during therapy(most oftern fact VIII inhibitors). Please indicate the specific factor inhibitor if factor assays have already been tested in your laboratory.
Specimen Sources
Blood, ArterialBlood, CapillaryBlood, Central LineBlood, Venous
Specimen Types
Blood
Container
Blue Top Tube
Collection Instructions
Contact the Coagulation Department at 516-224-8521 to answer questions or to provide additional information.
** Please indicate on the request or in computer the specific factor to be investigated.
Container/Tube: Light blue-top (3.2% sodium citrate) tube Specimen: Full tube Transport Temperature: Refrigerate
Collection Instructions: If the light blue top tube is the only tube to be drawn and will be collected using a butterfly set, a “discard” tube (either a plain[non-additive] or light blue) must be partially drawn just to completely fill the collection tubing with blood before collecting the light blue top for testing. Failure to perform this step will result in an under-filled tube that the laboratory will reject. Allow blood to fill the tube completely to the line on the tube. The ratio of blood to anticoagulant is critical in coagulation testing and at least a 90% fill is required. Immediately mix the specimen by gently inverting the tube 4-6 times to completely mix with the anticoagulant. Failure to perform this can result in a clotted sample, which is unacceptable for testing. If centrifugation of the specimen cannot be performed immediately after collection, whole blood can be kept in the blue top tube at room temperature (18-24° C) for up to 4 hours for the APTT and up to 24 hours for a PT/INR. For additional coagulation assays, whole blood cannot be refrigerated or frozen.
If centrifugation is possible, and transport to the lab will not occur within 1 hour, spin down, remove the plasma to a clean plastic transport tube using a plastic transfer pipette, and spin the plasma again. Remove the plasma with a clean plastic transfer pipette to a fresh transport container and freeze this citrated platelet-poor plasma immediately. A double centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results. Each coagulation assay requested should have its own vial of citrated plasma, 1.0mL each.
