Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Catastrophic antiphospholipid syndrome
Rapid thrombosis affecting three or more organs over days, often with kidney, lung, brain, skin, adrenal or cardiac injury and thrombocytopenia, is a high-mortality thrombo-inflammatory emergency.
Action: Use ABCDE and organ-specific critical care, involve haematology, rheumatology and the affected specialties immediately, obtain coagulation, haemolysis, antiphospholipid and infection samples without delaying treatment, begin therapeutic heparin when bleeding permits, give high-dose corticosteroid and arrange plasma exchange or intravenous immunoglobulin through the specialist CAPS pathway while treating infection or another trigger.
Synopsis
Confirm antiphospholipid syndrome only when a compatible clinical event and persistent antibodies coexist, select durable antithrombotic or pregnancy treatment, and recognise catastrophic APS promptly.
APS requires a compatible clinical event plus persistent antiphospholipid antibodies; a positive test alone is not the syndrome and should not automatically trigger anticoagulation.
First-line laboratory panel is lupus anticoagulant, anticardiolipin IgG and IgM and anti-beta2-glycoprotein I IgG and IgM, chosen because risk and classification differ across isolated and triple-positive profiles.
Confirm persistence by repeating the positive test at least 12 weeks later; acute thrombosis, inflammation and anticoagulants can distort results, especially lupus anticoagulant testing.
Key red flags
New hypoxaemia, kidney injury, encephalopathy, livedoid necrosis, adrenal failure or myocardial injury developing across several systems over less than a week suggests catastrophic APS rather than isolated VTE.
Catastrophic tempo
Kidney, lung, brain, skin or adrenal dysfunction developing together over days demands immediate CAPS, sepsis, TTP and DIC evaluation.
Investigation priorities
01
First-line: complete antiphospholipid antibody panelFirst stepFirst line
Identify lupus anticoagulant, anticardiolipin and anti-beta2-glycoprotein I positivity and define risk profile.
Management branches
Suspected thrombotic APSTreat clot and prove persistence
Objective venous, arterial or small-vessel thrombosis occurs with autoimmune clues, young age, unusual site or recurrence.
Treat the acute event immediately and obtain a full antiphospholipid panel before anticoagulation when feasible without delay.
Review infection, cancer, SLE, cardiovascular risks, medicines and hereditary factors, and arrange repeat positive antibodies after at least 12 weeks.
Key medicines
Warfarin after venous thrombotic APSStart with therapeutic heparin overlap and individualise oral warfarin to an INR target of 2.0–3.0 for a first venous APS event; continue long term unless specialist reassessment identifies a compelling reason to stop or change strategy.
Low-dose aspirin with prophylactic enoxaparin for obstetric APSUse aspirin 75–150 mg orally once daily and, when the obstetric APS plan indicates, enoxaparin 40 mg subcutaneously once daily from the specialist-defined early-pregnancy point, adjusted for weight, renal function and thrombosis history.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.