Hypercoagulability Flashcards
What percentage of population have inherited thrombophilia? What pecentage of people with VTE have inherited thrombophilia?
10% 50%
Most common inherited thrombophilias?
• 6% of population have Factor V Leiden - white people • 2% of population have Prothrombin gene mutation - white people • 0.4% of population have Protein C deficiency - asian people • 0.1% of population have Protein S deficiency • 0.02% of population have antithrombin III deficiency Black people more affects by elevated factor 8 & sickle cell disease
when should you test for hereditary thrombophilia?
with unprovoked DVT or PE and it is planned to stop treatment.
what is Factor V leiden mutation?
It is due to a gain of function mutation in the Factor V Leiden protein. The result of the mis-sense mutation is that activated factor V (a clotting factor) is inactivated 10 times more slowly by activated protein C than normal. This explains the alternative name for factor V Leiden of activated protein C resistance
Risk of VTE with Factor V Leiden?
4-fold heterzygous 10-fold homozygous
Relative risks of VTE with COCP, in pregnancy and in post-partum?
Normal: 1/5,000 risk (RR=1) COCP: RR=2.5 Pregnancy: RR=15 Post-partum: RR= 150
when to stop COCP and HRT before elective surgery?
4 weeks
Anti-VTE measures for surgery (non-pharm)?
Anti-embolism stockings mobilise early hydration intermittent pneumatic compression
Length of time on LMWH for acute medical patients, elective hip, elective knee, chest/abdo surgery?
7 days 28 days 14 days 7 days
LMWH in pregnancy?
Previous unprovoked VTE or 4 risk factors: LMWH from booking to 6 weeks pp Previous provoked VTE, thrombophilia, medical conditions or 3 risk factors: LMWH from 28 weeks to 10 days pp 2 risk factors: 10 days pp LMWH Admission to hospital, or >3 days postnatally, LMWH Risk factors worth 1 point: BMI>30, age>35, parity >3, smoker, C/S, varicose veins, PET, immobility, FH, IVF, twins, prolonged labour.
Warfarin in pregnancy causes?
○ Hypoplasia of nasal bridge ○ Congenital heart defects ○ Ventriculomegaly ○ Agenesis corpus callosum ○ Stippled epiphyses
Pregnancy risks of VQ scan vs CT scan?
• In women with suspected PE without symptoms and signs of DVT, a ventilation/perfusion (V/Q) lung scan or a computerised tomography pulmonary angiogram (CTPA) should be performed. [New 2015] • When the chest X-ray is abnormal and there is a clinical suspicion of PE, CTPA should be performed in preference to a V/Q scan. [New 2015] • Alternative or repeat testing should be carried out where V/Q scan or CTPA is normal but the clinical suspicion of PE remains. Anticoagulant treatment should be continued until PE is definitively excluded. Women with suspected PE should be advised that, compared with CTPA, V/Q scanning may carry a slightly increased risk of childhood cancer but is associated with a lower risk of maternal breast cancer; in both situations, the absolute risk is very small. [New 2015]
What anticoagulants can be used in breastfeeding?
warfarin and LMWH
Generally, by what percentage does warfarin reduce risk of VTE event?
by two-thirds from 3.7% of people to 1.2% with CHADVASC of 3
Generally, by that percentage does warfarin increased risk of serious bleeding event?
by two-thirds from 0.9% of people to 1.5% of people with HASBLED of 3
When you start warfarin, how do you monitor?
INR test on day 5 and 8 (so can only start on Mon, Thurs, Fri)
How does bleeding present with warfarin?
nose bleeds, black faeces, bruises, haemoptysis, menorrhagia more serious: intracranial
general advice for warfarin
keep diet steady, esp greens, eggs avoid cranberry juice, OTC don’t take NSAID, can take paracetamol stick to alcohol limits, be consistent avoid contact sports beware antibiotics
NOAC as alternative advice?
○ NOACs less risk of bleeding ○ Must not miss any NOAC dose because of shorter half-life ○ NOACs have less monitoring ○ NOACs do not have reversibility antidote
MOA of anticoagulants?
Rivaroxaban is a direct factor Xa inhibitor. Apixaban is also a direct factor Xa inhibitor. Dabigatran is a direct thrombin inhibitor. Heparin activates antithrombin III (which inhibitis Xa and thrombin). Warfarin inhibits activation of clotting factors II, VII, IX and X (and protein C&S) by inhibiting vitamin K epoxide reductase.
contraindicaionts for DOACs?
renal failure heart valves
RF for blood clots?
• Previous VTE • Cancer • Age • Obesity • Male • HF • Thrombophilia • Inherited: Mutated Factor V Leiden, Protein C deficiency, Protein S deficiency, Anti-thrombin deficiency • Acquired: Antiphospholipid syndrome, Primary and Secondary Polycythaemia, Thrombocytosis (essential and secondary to bleeding, infection, malignancy, vasculitis, surgery) • Smoking • Chronic low-grade injury to vascular wall • Vasculitis • Venous stasis • Chemotherapy TEMPORARY • Immobility • Trauma • HRT • Pregnancy and postpartum • Dehydration
DDx for DVT
• Trauma • Thrombophlebitis • Post-thrombotic syndrome (ie after previous DVTs) • Baker’s cyst • Cellulitis • Dependent oedema
Sx for DVT
• Unilateral • Generalized Pain • Generalized Swelling • Skin colour change: erythema / purple • Temperature normally up • Vein distension - “palpable cord”
