Taipan snake venom time (TSVT) and ecarin time (ET)


Alternative names, keywords


Samples required

2x trisodium citrate blood (blue cap, 3.5 mL tube) taken with minimal stasis, filled to the line.

Samples must be analysed or processed in the laboratory within 2 hours of venepuncture. Ideally patients should attend phlebotomy at the hospital to facilitate this.

Patients on DOACs should have samples collected at a ‘trough’ level, i.e. immediately prior to their next dose.

Test indications

Lupus anticoagulant screen for patients on Warfarin or an anti-Xa direct oral anticoagulant (DOAC).

Test information

May be affected if the INR on the sample is over 3.5 and thus rejected as a consequence.

Reference range

Reported by means of interpretive comment based upon on screening tests and the degree of correction of that test, as per current BCSH guidelines (e.g. ‘Lupus anticoagulant not demonstrated’.)

TSVT             0.91 - 1.09
Ecarin Time   0.87 - 1.14

A greater than 10% correction of the screening test with its confirmatory assay is considered indicative of LA.

A less than 7% correction of the screening test is considered not indicative of LA, i.e. negative.

Between 7% and 10% is equivocal and a repeat will be requested.

Turnaround time

1 month


Haematology (Coagulation)