ANTIPHOSPHOLIPID SYNDROME – MAKING THE DIAGNOSIS
Levine JS, Branch DW, Rauch J. The antiphospholipid syndrome. N Engl J Med. 2002;346(10):752-63.
International Consensus Statement – Criteria for the Definite Diagnosis of APLS:
In order to make the definitive diagnosis of APLS, the patient must meet at least one clinical criteria and at least
one laboratory criteria.
• Vascular thrombosis (arterial, venous, or small-vessel thrombus in any organ)
• Complication of pregnancy
- > 1 unexplained fetus death after 10 weeks (morph. normal fetus)
- > 1 premature births before 34 weeks (morph. normal fetus)
- > 3 unexplained consecutive spontaneous abortions before 10 weeks of gestation
• Anticardiolipin antibodies (positive on two or more occasions, at least six weeks apart)
• Lupus anticoagulant antibodies (positive on two or more occasions, at least six weeks apart)
Making the laboratory diagnosis: assumes that the patient is not currently receiving anticoagulation…
Step 1: Is the PTT elevated?
If yes, proceed directly to mixing study.
If no, check dilute Russell viper venom time (RVVT). The RVVT is more specific to the part of the
coagulation cascade that requires phospholipids. Therefore, the RVVT is a more sensitive test for
If the RVVT is normal, STOP Æ the patient most likely does not have APLS
If the RVVT is prolonged (abnormal), proceed to the mixing study.
Step 2: Does the mixing study correct the prolonged PTT (or RVVT)?
If yes, the problem is most likely a factor deficiency. Run an “incubated” mixing study. If the PTT
remains corrected, the problem is a factor deficiency. If the PTT (or RVVT) begins to prolong again,
If no, the problem is either APLS or a factor inhibitor.
Step 3: Does the PTT (or RVVT) correct with addition of excess phospholipids?
If yes, you have your diagnosis: antiphospholipid syndrome.
If no, the problem is a factor inhibitor.