Antiphospholipid syndrome Flashcards
What is antiphospholipid syndrome?
An autoimmune disorder in which antibodies are targeted against phospholipid binding proteins (phospholipids are major component of cell membranes)
What percentage of women with recurrent miscarriage have antiphospholipid syndrome?
15%
Describe the action of the antibodies in vitro
Inhibit assembly of phospholipid complexes and inhibit coagulation
Describe the action of the antibodies in vivo
Induce a procoagulant state
What are the obstetric complications of antiphospholipid syndrome due to?
Inhibition of trophoblastic function and differentiation
Activation of the complement pathways at the maternal-foetal interface
Thrombosis of the uteroplacental vasculature
What are trophoblasts?
Precursor to placenta
What other diseases is antiphospholipid syndrome associated with?
Other autoimmune disorders - SLE, RA, systemic sclerosis
What are the defining clinical features of antiphospholipid syndrome
Thrombosis formation and/or recurrent pregnancy loss
Describe thrombosis in antiphospholipid syndrome
Arterial
Venous
Microvascular
What is the main feature in obstetrics of antiphospholipid syndrome
Recurrent pregnancy loss at any age
What other obstetric conditions is antiphospholipid syndrome associated with?
Pre-eclampsia
Intrauterine growth restriction
List some other manifestations of antiphospholipid syndrome
Livedo reticularis
Valvular heart disease - regurgitation
Renal impairment
Thrombocytopenia
What is livedo reticularis
Red/blue/purple reticular pattern on the skin of the trunk, arms or legs
Which valves are most affected in antiphospholipid syndrome
Aortic and mitral regurgitation
Describe the renal impairment in antiphospholipid syndrome
Ischaemia in the small vessels of the kidney can result in chronic kidney disease
Describe catastrophic antiphospholipid syndrome
Rare complication
1% of cases
Acute formation of microthromboses which causes infarction of multiple organs
20% triggered by major surgery, trauma or infection
Mortality rate of 50%
What are the 3 main blood tests for antiphospholipid syndrome diagnosis?
Anticardiolipin
Lupus anticoagulant
Anti-B2-glycoprotein 1
Describe anticardiolipin
Measures antibodies that bind cardiolipin (phospholipid)
Describe lupus anticoagulant
Measures the clotting ability of the blood
Describe the clotting ability of the blood in antiphospholipid syndrome
Prolonged clotting time in vitro
Describe anti-B2-glycoprotein1
Detects antibodies that bind B2-glycoprotein 1 (a molecule that binds with cardiolipin)
What percentage of healthy individuals test positive for antiphospholipid syndrome?
5%
Describe the diagnostic criteria of antiphospholipid syndrome
1 clinical criteria plus 1 laboratory criteria
Clinical criteria:
- Vascular thrombosis - >1 episode of arterial, venous or small vessel thrombosis
- Pregnancy morbidity - >3 unexplained consecutive spontaneous abortions <10 weeks gestation or >1 premature birth of a normal neonate <34weeks because of eclampsia/severe pre-eclampsia or >1 unexplained death or morphologically normal foetuses at or beyond the 10th week gestation
Lab criteria
- Lupus anticoagulant - present in plasma on >2 occasions >12hr apart
- Anticardiolipin antibody - present in medium/high titre on >2 occasions >12 weeks apart
- Anti-beta2-glycoprotein 1 - present in serum or plasma on 2 or more occasions at least 12 weeks apart
What does the management of antiphospholipid syndrome depend on?
The clinical presentation of the patient
Describe the management of antiphospholipid syndrome in someone presenting with recurrent pregnancy loss >3
LMWH and Low dose aspirin (75mg OD)
Describe the management of antiphospholipid syndrome in someone presenting with previous pre-eclampsia/IUGR
Low dose aspirin (75mg) throughout subsequent pregnancy
Describe the management of antiphospholipid syndrome in someone presenting with vascular thrombosis
Long term anticoagulation with warfarin (target INR 2-3). Target INR can be increased if thrombosis was arterial
Switch warfarin to LMWH if pregnant/trying to conceive
