What does an elevated dilute Russell viper venom (DRVVP) screen of 58.4 seconds with a normal confirmatory DRVVP result indicate?

Interpretation of Elevated DRVVP Screen with Normal Confirmatory Test

Your result pattern—prolonged DRVVP screen (58.4 seconds) with normal DRVVP confirm—is negative for lupus anticoagulant and does not meet diagnostic criteria for antiphospholipid antibodies. 1, 2, 3

Understanding the Test Algorithm

The dilute Russell's viper venom time (dRVVT, also called DRVVP) follows a three-step diagnostic sequence to identify lupus anticoagulant (LA):

Step 1: Screening Test

• Your screen result of 58.4 seconds is prolonged compared to normal pooled plasma, which initially suggests the possibility of LA 1, 3
• A prolonged screening time alone is not diagnostic—it only indicates the need for further testing 1, 2

Step 2: Confirmatory Test (Phospholipid Dependence)

• The confirmatory test adds high phospholipid concentration to the same assay 1, 3
• True lupus anticoagulant will show correction (shortening of clotting time) when excess phospholipid is added, because LA antibodies interfere with phospholipid-dependent coagulation 1, 2, 3
• Your normal (within normal limits) confirmatory result means the prolonged screen did NOT correct with added phospholipid 1, 2, 3

Step 3: Interpretation

• LA is confirmed only when percentage correction exceeds the laboratory cut-off, calculated as: [(screen time – confirm time) / screen time] × 100 1, 2, 3
• Your result pattern (prolonged screen, normal confirm) indicates the prolongation is NOT phospholipid-dependent, therefore NOT lupus anticoagulant 1, 2, 3

What Could Cause This Pattern?

When the screen is prolonged but the confirm is normal (no correction), consider:

• Factor deficiency (factors II, V, X)—these will prolong both low and high phospholipid assays similarly, so the ratio/correction calculation remains normal 1, 3
• Mild anticoagulant effect (heparin < 0.8 U/mL, residual warfarin)—may prolong the screen without showing phospholipid-dependent correction 3, 4
• Technical/pre-analytical issues (inadequate centrifugation, platelet contamination, delayed processing)—can cause non-specific prolongation 1, 3
• Acute phase reactants or elevated factor VIII—may affect baseline clotting times without creating phospholipid dependence 3

Critical Next Steps

If clinical suspicion for antiphospholipid syndrome remains high (unprovoked thrombosis, recurrent pregnancy loss, young stroke), you must:

• Perform the second required screening test—a sensitive aPTT with low phospholipid and silica activator—because no single test detects all lupus anticoagulants 1, 3
• Check anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies (IgG and IgM isotypes), as these complete the antiphospholipid antibody profile 3, 5
• Review medication history—ensure testing was done off anticoagulation or with appropriate washout (warfarin stopped 1-2 weeks, INR < 1.5; heparin stopped > 12 hours) 3, 4
• Verify specimen quality—confirm double centrifugation was performed to achieve platelet-poor plasma (< 10⁷ platelets/mL) 1, 3

Common Pitfalls to Avoid

• Do not diagnose LA based on screening test alone—the confirmatory step is mandatory to demonstrate phospholipid dependence 1, 2, 3
• Do not assume a single negative dRVVT rules out LA—you must also test with sensitive aPTT, as different antibodies react with different assays 1, 3
• Do not test during acute anticoagulation with DOACs—rivaroxaban and other direct oral anticoagulants cause false-positive dRVVT results in most reagent systems 6
• Do not order LA testing in low-risk populations (asymptomatic individuals, routine screening)—false-positives are common and lead to unnecessary long-term anticoagulation 1

Clinical Context Matters

• If tested for isolated prolonged aPTT without thrombosis—the likelihood of eventual APS diagnosis is extremely low, even with equivocal dRVVT results 7
• If tested for thrombosis—a prolonged dRVVT that does not meet both ISTH and manufacturer positivity criteria is rarely associated with APS diagnosis 7
• Triple positivity (LA + aCL + aβ2GPI of the same isotype) identifies the highest thrombosis risk; isolated borderline results often represent false-positives, especially in elderly patients 3, 5