Interpretation

Dilute Russell's viper venom time screen ratio (<1.20):

A normal dilute Russell's viper venom time (DRVVT) screen ratio (<1.20) indicates that lupus anticoagulant (LA) is not present or not detectable by this method (but might be detected with other methods).

An abnormal DRVVT screen ratio (DRVVT screen ratio ≥1.20) may suggest presence of LA, however, other possibilities include:

-Deficiencies or dysfunction of factors I (fibrinogen), II, V, or X, congenital or acquired

-Inhibitors of factor V, or occasionally by inhibitors of factor VIII, or other specific or nonspecific inhibitors

-Anticoagulation therapy effects (see Cautions)

Further evaluation consists of performing mixing studies with an equal volume of normal pooled plasma (DRVVT 1:1 mix) to investigate the possibility of coagulation factor deficiency (suggested by DRVVT mix ratio <1.20) and to evaluate inhibition (suggested by DRVVT mix ratio ≥1.20) and mixing patient plasma with DRVVT reagent enriched in phospholipid (DRVVT confirmatory reagent) (DRVVT mix and DRVVT confirmation ratios).

Possible combination of results includes the following:

-DRVVT screen ratio ≥1.20, DRVVT mix ratio <1.20, and DRVVT confirmation ratio <1.20:

No evidence of LA. These data may reflect anticoagulation therapy effects or other (congenital or acquired) coagulopathy.

-DRVVT screen ratio ≥1.20, DRVVT mix ratio ≥1.20, and DRVVT confirmation ratio <1.20:

The prolonged and inhibited DRVVT (DRVVT screen and mix ratios) may reflect presence of a specific factor inhibitor (eg, factor V inhibitor), anticoagulation therapy effects or other nonspecific inhibitors as can be seen with monoclonal protein disorders, lymphoproliferative disease etc. Although LA cannot be conclusively excluded, the DRVVT confirmation ratio of ≤1.20 makes this less likely.

-DRVVT screen ratio ≥1.20, DRVVT mix ratio <1.20, and DRVVT confirmation ratio ≥1.20:

Although mixing study of the prolonged DRVVT screen and mix ratios provides no evidence of inhibition, additional phospholipid shortens the clotting time (DRVVT confirm ratio), suggesting presence of LA.

-DRVVT screen ratio ≥1.20, DRVVT mix ratio ≥1.20, and DRVVT confirmation ratio ≥1.20:

The data are consistent with presence of LA, provided anticoagulant effect can be excluded (see Cautions)

Because no single coagulation test can identify or exclude all LAs, and because of the complexity of testing LA, one of the following Coagulation Consultation reflexive panel procedures is recommended if clinically indicated:

ALUPP / Lupus Anticoagulant Profile, Plasma

AATHR / Thrombophilia Profile, Plasma and Whole Blood

APROL / Prolonged Clot Time Profile, Plasma

DRVVT assays ordered as a single, stand-alone test should be interpreted within patient clinical context and close attention to medication use by patient (see Cautions).