LAC (LUPUS ANTICOAGULANT) DRVVT (dilute Russell viper venom test ), in Visit Clinic

A positive Russell viper venom test suggests the presence of lupus anticoagulant—an antiphospholipid antibody linked to higher risk of blood clots (venous/arterial) and pregnancy complications. It needs repeat confirmation (mixing and phospholipid-neutralization tests) and clinical correlation because anticoagulants, acute illness, or transient antibodies can cause false positives. Diagnosis of antiphospholipid syndrome requires persistent positivity at least 12 weeks plus clinical events.

Testing positive for lupus anticoagulant means you have antibodies that prolong clotting tests but raise the risk of blood clots and pregnancy complications. It can indicate antiphospholipid syndrome if antibodies persist alongside clinical events. Results may be transient after infection or medications. Repeat testing, review of clotting or pregnancy history, and discussion about monitoring or anticoagulation with your clinician are recommended.

The dilute Russell viper venom time (dRVVT) is reported as seconds and often as a patient/normal pooled plasma ratio. A typical normal ratio is below about 1.2 (cutoffs commonly 1.2–1.3); raw clotting times are assay- and lab-dependent (commonly ~30–40 seconds). Labs use assay-specific reference ranges and confirmatory tests; anticoagulant therapy or acute illness can alter results.

Russell viper venom is used diagnostically in coagulation testing: diluted Russell viper venom time (dRVVT) and related assays use the venom’s ability to directly activate factor X to detect lupus anticoagulant (antiphospholipid antibodies) and to evaluate phospholipid-dependent clotting inhibitors. It’s also used in research and specialized coagulation factor assays to study or measure clotting pathways.

Treatment requires prompt intravenous antivenom (species-appropriate polyvalent or monovalent) plus supportive care: airway/oxygen, IV fluids and vasopressors for shock, pain control, tetanus prophylaxis, wound care, and monitoring/correction of coagulopathy with blood products. Provide dialysis for acute kidney injury and surgical treatment only for confirmed compartment syndrome. Immobilize the limb and keep the patient calm; avoid cutting, suction, or tight tourniquets.

DRVVT is not routine; it’s done when lupus anticoagulant is suspected—unexplained thrombosis, recurrent pregnancy loss, prolonged aPTT, or signs of antiphospholipid syndrome. Results need mixing and confirmatory tests and can be affected by anticoagulants. For an antiphospholipid syndrome diagnosis, positive antibodies must persist on repeat testing at least 12 weeks apart. Discuss timing with your clinician.