This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': '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 ? \nSelect and explain. \nA. Factor VIII assay, B. Dilute russel viper venom assay, C. Platelet aggregation test, D. Ristocetin cofactor assay', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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)', 'role': 'assistant'}]