Pitfalls in the assessment of disseminated intravascular coagulation in patients on dabigatran

Simplified Method for Removing Direct Oral Anticoagulant Interference in Mechanical Coagulation Test Systems-A Proof of Concept

BACKGROUND

Direct oral anticoagulants (DOACs) cause unwanted interference in various hemostasis assays, including lupus anticoagulant (LA) testing, where false positive and false negative identification may occur. DOAC Stop (DS) is an activated charcoal (AC) product used to specifically and effectively adsorb DOACs from test plasma. This process normally requires plasma treatment, centrifugation and plasma separation prior to tests, but inexperienced operators may also inadvertently transfer residual AC particles, thereby potentially adversely affecting clot detection.

METHODS

We hypothesized that residual DS might not be problematic for mechanical clot detection. We therefore investigated the potential impact of DS and a new DS liquid (DS-L) product on clotting tests using a mechanical clot detection system. Varying concentrations of DS were added to normal and abnormal plasmas with and without DOAC presence. Clotting tests including PT, APTT and dRVVT were performed directly in the analyzer without plasma/DS centrifugation.

RESULTS

DS up to double the recommended treatment level had only minor effects on all test results, despite completely obscuring visibility in the plasma/reagent mix. This confirms that the centrifugation step may be able to be omitted when using mechanical detection systems.

CONCLUSIONS

Should DS carryover into treated plasmas occur, this should not cause issues with testing performed on mechanical clot-sensing devices. Moreover, we hypothesize that DS can be used directly in these systems, without the need for centrifugation, thereby simplifying its many potential applications.

International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders

This guidance was prepared on behalf of the International Council for Standardisation in Haematology (ICSH) by an international working group of clinicians and scientists. The document focuses on tests and assays used for the assessment of fibrinogen function, particularly in the scenario of bleeding disorders. Thrombin clotting time (TT) is used as a screening test in some laboratories and also has some utility when direct anticoagulants are in use. The Clauss fibrinogen assay remains the method of choice for the assessment of fibrinogen function, but there are some situations where the results may be misleading. Prothrombin time derived fibrinogen assays are frequently used, but should be interpreted with caution; the results are not interchangeable between different methods and fibrinogen can be overestimated in certain clinical scenarios. Viscoelastic point of care methods may be helpful in emergency situations, while Reptilase time (and similar tests) are useful combined with TT in distinguishing heparin contamination of samples (i.e., if an incorrect blood draw is suspected) and the presence of direct thrombin inhibitors. Fibrinogen antigen assays should be used in the investigation of functional fibrinogen abnormalities; fibrinogen antigen and genetic testing are recommended in the confirmation of congenital fibrinogen disorders. The following recommendations for fibrinogen function assessment are based on published literature and expert opinion and should supplement local regulations and standards.