Diagnosis of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a rheumatic disease characterized by the presence of autoantibodies to phospholipids. The causes of autoantibody formation have not been precisely determined. It is believed that most human viruses are tropic to the vascular endothelium. Persisting in them, viruses cause morphological and functional changes in cells; the resulting destruction of the main membrane of the vessel walls, caused by damage to the endothelium, leads to the activation of factor XII (Hageman) of the blood coagulation system and the development of hypercoagulation, as well as the production of autoantibodies. Autoantibodies block endothelial membrane proteins (protein C, S, thrombomodulin), which prevent thrombus formation, suppress the activation of the coagulation cascade components, inhibit the production of ATIII and prostacyclin, and have a direct damaging effect on vascular endothelial cells. The interaction of antibodies with phospholipids of cell membranes leads to conformational and metabolic changes in membranes, disruption of cell function, blood stasis in capillaries and venules, and thrombosis.

In some patients, antiphospholipid syndrome manifests itself primarily as venous thrombosis, in others - as stroke, and in others - as obstetric pathology or thrombocytopenia.

Frequency of antiphospholipid syndrome in various conditions

States	Frequency,%
Recurrent venous thrombosis	28-71
Habitual miscarriage	28-64
Transverse myelitis	50
Thrombocytopenia	27-33
Hemolytic anemia	38
Arterial thrombosis	25-31
Mesh Livedo	25
Pulmonary hypertension	20-40

The diagnostic criteria for antiphospholipid syndrome were formulated in 1998 at the VIII International Symposium on Antiphospholipid Antibodies in Sapporo (Japan).

Clinical and laboratory criteria for the diagnosis of antiphospholipid syndrome

Clinical criteria

• Vascular thrombosis

One or more clinical episodes of arterial, venous, or small vessel thrombosis in any tissue or organ. Thrombosis must be confirmed by ultrasound Doppler imaging or histological examination, with the exception of superficial venous thromboses. Histological examination of thrombosis must present significant inflammatory changes in the vessel wall

• Diseases of pregnant women

One or more unexplained deaths of a morphologically normal fetus at or after 10 weeks of normal pregnancy, where normal fetal morphology must be documented by ultrasound scanning or direct fetal examination,

Or

:

One or more preterm births of a morphologically normal fetus at or before 34 weeks of gestation due to severe preeclampsia or eclampsia, or severe placental insufficiency,

Or: three or more unexplained consecutive abortions before 10 weeks of pregnancy with pathological or anatomical anomalies, or hormonal disorders, and chromosomal causes must be excluded in the father and mother

Laboratory criteria

1. Anticardiolipin antibodies IgG and/or IgM in blood, moderate or high level in 2 or more studies obtained at least 6 weeks apart, measured by standard ELISA for β2 _- glycoprotein 1-dependent anticardiolipin antibodies
2. Positive lupus anticoagulant in plasma in 2 or more assays obtained at least 6 weeks apart, with this anticoagulant determined according to the International Society on Thrombosis and Haemostasis guidelines using the following steps:
   • establishing the fact of prolongation of the phospholipid-dependent phase of plasma coagulation based on the results of screening tests such as APTT, coagulin time, Russell test with dilution, prothrombin time with dilution
   • inability to correct for prolonged screening test times by mixing with normal platelet-free plasma
   • shortening the screening test time or normalizing it after adding excess phospholipids to the plasma being tested and excluding other coagulopathies, such as the presence of a factor VIII inhibitor or heparin

Diagnosis conditions

Presence of at least one clinical and one laboratory criterion

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