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Antiphospholipid syndrome C035

Last amended 
18 April 2023
Current RMA Instruments
Reasonable Hypothesis SOP69 of 2016
Balance of Probabilities SOP 70 of 2016
SOP bulletin information on new SOPs

SOP Bulletin 192

ICD Coding
  • ICD-9-CM Codes:289.81
  • ICD-10-AM Codes: D68.61
Brief description

Antiphospholipid syndrome is a rare autoimmune condition which occurs as a primary condition, or in the setting of another autoimmune disorder, e.g. systemic lupus erythematosus.  It causes:

  • otherwise unexplained thrombotic events in arteries, veins and small vessels, that can occur anywhere in the body, resulting in a wide range of clinical manifestations, including strokes, myocardial infarctions and DVTs, and;

  • pregnancy complications, resulting in manifestations such as embryo loss, foetal death and premature birth.

Confirming the diagnosis

The diagnosis is made based on the clinical presentation and positive laboratory testing for specific antiphospholipid antibodies (as per the SOP definition).  The testing involves initial testing around the time of a clinical event and, where positive, confirmatory testing at least 12 weeks later.  For catastrophic antiphospholipid syndrome confirmatory testing may be undertaken sooner, at least six weeks after intial testing.  Positive antibody testing in the absence of relevant clinical manifestations does not establish the diagnosis.

The relevant medical specialist is a haematologist, immunologist, general physician or obstetrician (for preganancy-related aspects).

Additional diagnoses covered by SOP
  • Antiphospholipid antibody syndrome
  • Catastrophic antiphospholipid syndrome
Clinical onset

Once the diagnosis (and the presence of relevant antibodies) has been confirmed, clinical onset can be dated to the onset of the first clinicial event (vascular thrombosis or pregnancy morbidity) that is clinically adjudged by a treating medical specialist to be a manifestation of the condition.

Clinical worsening

Patients with this condition are at risk of subsequent thrombotic events or pregancy morbidity.  The occurence of such events may represent a clinical worsening, where there has been a precipitating factor.  Treatment with anticoagulant/antiplatelet therapy is effective in preventing new events.  For catastrophic antiphospholipid syndrome additional treatment with systemic glucocorticoids (steroids) and plasma exchange therapy is generally provided.