Utility of Lupus Anticoagulant Assays (APTT-LA, KCT, DPT and DRVVT) in Detection of Antiphospholipid Syndrome (APS) in High Risk Pregnancy Cases

Routine investigation for recurrent pregnancy loss includes measurement of antiphospholipid antibodies. The lupus anticoagulant has long been associated with increased risks for thrombosis and adverse obstetric outcomes. But there are some disadvantages with lupus anticoagulant (LAC) tests which includes varied sensitivity of different clot based assays. ISTH recommends only 2 assays (preferably DRVVT and APTT-LA) for the identification of lupus anticoagulant but there are some studies which don't support this contention. Our study analyzed 526 samples from high risk pregnancy cases for APLA by all four LAC tests from tertiary centre of northern India. Among all the cases studies 65 cases were positive for lupus anticoagulant 25 of this became negative after 12 weeks. Among the 40 repeated positive assays, dRVVT could able to diagnose 36 cases followed by APTT-LA which could able to diagnose 28 cases, while KCT could able to diagnose 23 cases and dPT could able to diagnose only 14 cases. There were 12 cases in whom all lupus assays were positive. Our study thus concluded that DRVVT was the most sensitive followed by APPT-LA, KCT, dPT. The combination of dRVVT with APTT-LA or KCT appeared to be superior to other combinations. No individual test per se is 100% sensitive for the diagnosis of APLA in high risk pregnancy cases. Further results confirmed that repeated LAC result is required even in a high-risk setting. Positive LAC assay in majority were not associated with exclusively recurrent pregnancy loss but were associated with sporadic stillbirth and thrombosis.