45 yr old female for pre-surgery hemostatic evaluation has PT 13.5 sec(control 11-15s) and APTT 48s (control 26-39s).she does not give history of excessive bleeding following lap cholecystectomy done 2 yrs a go. Which of the following should be done? (AIIMS Nov 2010)
|A||Factor VIIIc assay|
|B|| Platelet aggregation test|
|C||Dilute Russell viper venom time|
|D||Ristocetin co-factor assay|
Ref: Harrison, 17th edition, page - 2079
Dilute Russell's viper venom time(dRVVT) is a lab test often used for detection oflupus anticoagulant(LA).
a. An additional autoantibody test with predictive value (not used for diagnosis) detects anti-Ro, which indicates increased risk for neonatal lupus, sicca syndrome, and Sub acute cutaneous lupus erythematosus (SCLE).
b. Women with child-bearing potential and SLE should be screened for aPL and anti-Ro.
Table - Classification and Nomenclature of Antiphospholipid Antibodies (Ref: H-18th edition, Pg-2736, table 320.1)
i. Antibodies against cardiolipin (aCL), detected by enzyme-linked immunosorbent assay (ELISA)
ii. Antibodies against b2GPI, (anti-b2GPI) detected by ELISA in the absence of PL.
iii. LA detected by clotting assays. LA constitutes a heterogeneous group of antibodies directed also against PL binding proteins, mainly b2GPI and prothrombin. LA antibodies induce Prolongation in vitro of the following clotting times:
a. aPTT, b. Kaolin clotting time (KCT), c. Dilute Russel viper venom test (dRVVT)
iv. Antibodies against phospholipids/cholesterol complexes detected as biologic false-positive serologic test for syphilis (BFP-STS) and VDRL