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 combinations of results include 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 confirmation 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)

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).