dRVVT

AKA Dilute Russell Viper Venom Time is an in vitro qualitative test for lupus anticoagulant (LA) and usually follows an elevated PTT when LA is suspected. The test is derived from the venom of Russell viper, a power thrombotic agent in vitro. A mixing study is performed combining Russell viper venom, patient’s plasma, and phospholipids, which is required for coagulation. The presence of Lupus Anticoagulant would prevent clotting. A prolonged clotting time would be followed up with a confirmatory test where excess phospholipids are added to the mixing study, which should overcome LA and induce clotting. A ratio between clotting time without excess phospholipids and with excess phospholids is then calculated. An elevated ratio is considered positive and consistent with LA.