A 45 year old lady with normal PT and increased aPTT. About 2 year back, she was operated for cholecystectomy & did not have any bleeding episode.What is next investigation for clinical diagnosis ?
Factor VIII assay
Dilute russel viper venom assay
Platelet aggregation test
Ristocetin cofactor assay
Answer- B. Dilute russel viper venom assayDilute Russel viper venom test is one of the test to detect lupus anticoagulant.Lupus anticoagulant is associated with prolongation in PTT and thrombosis (no bleeding)