A35 yr old lady with normal PT and increased aPTT. 2 year back, she was operated for cholecystectomy & did not have any bleeding episoe. What is next investigation for clinical diagnosis -

The dilute Russell viper venom test is a commonly used screening test for LA. It is called the dilute Russell viper venom time test because the phospholipid reagent is diluted such that its concentration becomes rate limiting; thus, it becomes a sensitive assay Ref Davidson 23rd edition pg 283