Which of the following is an appropriate screening test for the diagnosis of lupus anticoagulant?

The diluted Russell's viper venom test (DRVVT) is the appropriate screening test for the diagnosis of lupus anticoagulant. This test is specifically designed to detect the presence of inhibitors that interfere with the normal clotting processes, particularly those associated with lupus anticoagulants. Lupus anticoagulants are antibodies that can increase the risk of thrombosis and are commonly associated with autoimmune disorders such as systemic lupus erythematosus (SLE).

The mechanism of the DRVVT involves the use of Russell’s viper venom, which activates the coagulation cascade in a manner similar to tissue factor. The test assesses the time it takes for a clot to form in a sample of plasma mixed with the venom. If lupus anticoagulants are present, they will prolong the clotting time as they inhibit the activation of phospholipid-dependent clotting pathways.

Unlike the DRVVT, other tests such as thrombin time, D-dimer, and FDP assays serve different purposes in the assessment of bleeding disorders, thrombosis, or fibrinolysis rather than specifically screening for lupus anticoagulant. Therefore, the DRVVT stands out as the suitable choice for this specific diagnostic context.