Haematology: Haemostasias and Thrombosis

• Bleeding: Approach to Bleeding and Clotting Tests | Approach to Low Platelets | Immune Thrombocytopenia | Heparin-induced Thrombocytopenia | Haemophilia | Von Willebrand Disease | Other Bleeding Disorders
• Thrombosis: Diagnosing DVT | Treating Venous Thromboembolism | VTE in Special Situations | Preventing VTE in Hospital | Thrombophilia and Antiphospholipid Syndrome
• Anticoagulants: Using Anticoagulants Safely | Bleeding on Anticoagulants | Antiplatelet Drugs and Bleeding
• Revision: Drug Reference Table | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🩹 Haemostasis is a balance between bleeding and clotting. Too far one way causes bruising and haemorrhage; too far the other causes DVT, PE and stroke. Anticoagulants are among the drugs most often linked to harm in hospital, so using them safely is a core skill. Pulmonary embolism is covered in the Respiratory chapters, and TTP and DIC in the Haematological Emergencies chapter.
Your four questions for every patient: Is the bleeding pattern from platelets or from clotting factors? What do the platelet count, PT and APTT show? For a clot - was it provoked, and how long should treatment last? Is the anticoagulant, dose and kidney function right for this patient?

Approach to Bleeding and Clotting Tests

Bleeding history:

• Easy bruising; nosebleeds; gum bleeding.
• Heavy periods; bleeding after childbirth.
• Bleeding after dental extraction or surgery.
• Bleeding into joints or muscles.
• Family history.
• Drugs - anticoagulants, antiplatelets, NSAIDs, SSRIs, herbal remedies (ginkgo, fish oils).
• Liver and kidney disease.
• A structured bleeding score (e.g. ISTH-BAT) helps.

Two patterns:

• Platelet or vessel type (low platelets, VWD) - skin and mucosa: petechiae, purpura, nosebleeds, gum bleeding, heavy periods. Bleeding starts immediately after injury.
• Clotting factor type (haemophilia) - deep bleeding into joints and muscles; bleeding may be delayed after injury or surgery.

Interpreting clotting tests:

• Mixing study: If a prolonged test corrects when mixed with normal plasma, a factor is missing. If it doesn't correct, an inhibitor is present (lupus anticoagulant, acquired haemophilia).
• DOACs affect tests unpredictably - anti-Xa levels (drug-calibrated) or dabigatran levels measure them if needed.

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Approach to Low Platelets

First, exclude pseudothrombocytopenia - platelets clump in EDTA tubes. Check the film and repeat in a citrate tube.

Causes:

• Reduced production:
  • Marrow failure or infiltration (leukaemia, MDS, aplastic anaemia, cancer).
  • B12 or folate deficiency.
  • Alcohol.
  • Chemotherapy.
  • Viruses (HIV, hepatitis C).
• Increased destruction:
  • ITP.
  • Drugs - heparin (HIT), quinine, linezolid, valproate, co-trimoxazole, piperacillin, vancomycin, GP IIb/IIIa inhibitors.
  • SLE; antiphospholipid syndrome.
  • Post-transfusion purpura.
• Consumption: DIC, TTP, HUS, sepsis, HELLP syndrome, major bleeding.
• Sequestration: Hypersplenism (portal hypertension).
• Pregnancy: Gestational thrombocytopenia (mild, usually over 70 × 10⁹/L, late pregnancy, harmless); also pre-eclampsia, HELLP, ITP.
• Dilution: Massive transfusion.

How worried to be:

• Over 50 × 10⁹/L - spontaneous bleeding is rare.
• Under 20 - risk of bleeding rises.
• Under 10 - risk of serious spontaneous bleeding.
• Urgent same-day referral: Platelets under 20, active bleeding, other abnormal counts or blasts, or schistocytes (TTP).

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Immune Thrombocytopenia

What it is: Antibodies destroy platelets, and also reduce their production. It causes isolated thrombocytopenia (other counts and the film are normal). It is a diagnosis of exclusion.

• Children: Often follows a viral infection; sudden bruising and petechiae; usually resolves within weeks to months without treatment.
• Adults: More often chronic (over 12 months); commoner in women.
• Secondary causes to look for:
  • HIV, hepatitis C, H. pylori.
  • SLE; antiphospholipid syndrome.
  • CLL and lymphoma.
  • Drugs.
  • Common variable immunodeficiency.
  • Pregnancy.
• Features: Petechiae, purpura, nosebleeds, gum bleeding, heavy periods. Many have no symptoms. Serious bleeding (e.g. intracranial) is rare. No splenomegaly.
• When to treat: Bleeding, or platelets under about 20–30 × 10⁹/L, or before procedures - not the count alone.
• First line:
  • Prednisolone 1 mg/kg (short course, then taper), or dexamethasone 40 mg daily for 4 days.
  • IVIg for a rapid rise (severe bleeding, before surgery).
• Second line:
  • Thrombopoietin receptor agonists - eltrombopag, romiplostim, avatrombopag.
  • Rituximab.
  • Fostamatinib.
  • Mycophenolate.
  • Splenectomy (less common now; vaccinate first).
• Life-threatening bleeding:
  • IV methylprednisolone, IVIg, platelet transfusion (short-lived benefit), tranexamic acid.
  • Stop antiplatelets and NSAIDs.
• Pregnancy: Steroids or IVIg; plan delivery. The baby may be born with low platelets.

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Heparin-induced Thrombocytopenia

What it is: An immune reaction to heparin. Antibodies against heparin–platelet factor 4 (PF4) complexes activate platelets. This causes thrombocytopenia - and, paradoxically, thrombosis (arterial and venous).

• Timing: Platelets fall 5–10 days after starting heparin (sooner if heparin was given in the last 3 months).
• Features:
  • Platelets fall by more than 50% (usually not below 20).
  • New thrombosis - DVT, PE, limb ischaemia, stroke.
  • Skin necrosis at injection sites.
  • Reactions to IV heparin.
• Risk: Higher with unfractionated heparin than LMWH, and after surgery (especially cardiac and orthopaedic).
• Assess probability with the 4Ts score:
  • Thrombocytopenia.
  • Timing.
  • Thrombosis.
  • oTher causes.
  • If intermediate or high - test for anti-PF4 antibodies.
• Management (if intermediate or high probability, don't wait for results):
  • Stop all heparin - including flushes and heparin-coated lines.
  • Start a non-heparin anticoagulant at treatment dose (even without thrombosis) - argatroban, danaparoid, fondaparinux, or a DOAC.
  • Don't give platelets (they fuel thrombosis) unless bleeding is life-threatening.
  • Don't start warfarin until platelets recover (risk of skin necrosis and limb gangrene).
  • Scan the legs for silent DVT.
  • Record heparin allergy prominently.
• Related condition: Vaccine-induced immune thrombocytopenia and thrombosis (VITT) - after adenoviral vector COVID-19 vaccines; similar anti-PF4 antibodies.

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Haemophilia

What it is: An inherited deficiency of a clotting factor.

• Haemophilia A - factor VIII (about 5 in 6 cases).
• Haemophilia B - factor IX.
• X-linked recessive - affects males; female carriers can have low levels and bleed.

Severity by factor level:

• Severe (under 1%) - spontaneous bleeding into joints and muscles.
• Moderate (1–5%) - bleeding after minor injury.
• Mild (5–40%) - bleeding after surgery or major trauma; may be diagnosed late.

Features:

• Haemarthroses (knees, elbows, ankles) - lead to chronic joint damage.
• Muscle haematomas - iliopsoas bleeds cause hip flexion and femoral nerve compression.
• Bleeding after circumcision, dental work or surgery.
• Intracranial haemorrhage.

Tests:

• Prolonged APTT, normal PT and platelets.
• Low factor VIII or IX.
• Exclude VWD (which can also lower factor VIII).

Treatment (at a haemophilia centre):

• Factor replacement - recombinant factor VIII or IX (standard or extended half-life) for bleeds and as regular prophylaxis in severe disease.
• Emicizumab - a weekly to monthly subcutaneous antibody that mimics factor VIII, used as prophylaxis in haemophilia A.
• Gene therapy - available for selected adults (e.g. haemophilia B).
• Desmopressin - raises factor VIII in mild haemophilia A (fluid restriction afterwards - hyponatraemia risk).
• Tranexamic acid for mouth and nose bleeding.
• Inhibitors (antibodies against the factor) - bypassing agents (recombinant factor VIIa, FEIBA) or emicizumab.

Important rules:

• Treat any suspected bleed promptly - "factor first", before scans.
• Head injury in haemophilia - give factor, then image.
• Avoid IM injections, NSAIDs and aspirin.
• Patients carry treatment cards and often their own factor.

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Von Willebrand Disease

What it is: The commonest inherited bleeding disorder (up to 1 in 100 have low levels; about 1 in 10,000 have significant symptoms). Von Willebrand factor helps platelets stick, and carries factor VIII.

Types:

• Type 1 - partial shortage (mild; autosomal dominant; about 75%).
• Type 2 - abnormal function.
• Type 3 - almost none (severe, recessive; low factor VIII causes joint bleeds too).

Features:

• Mucocutaneous bleeding - nosebleeds, easy bruising, gum bleeding.
• Heavy menstrual bleeding (a common presentation - test women with heavy periods since menarche).
• Postpartum haemorrhage.
• Bleeding after dental extraction or surgery.

Tests:

• VWF antigen and activity; factor VIII.
• APTT may be normal or prolonged.
• Levels rise with stress, pregnancy, inflammation and the pill - repeat if normal but suspicion is high.
• Blood group O has lower levels.

Treatment:

• Tranexamic acid (heavy periods, dental work).
• Desmopressin (type 1) - test response first; restrict fluids (hyponatraemia).
• VWF-containing concentrates (type 2, 3, major surgery).
• Hormonal treatment for heavy periods (LNG-IUS).
• Avoid NSAIDs and aspirin.

Acquired VWD: Aortic stenosis (Heyde's syndrome - GI bleeding), LVADs, MGUS and lymphoproliferative disease, hypothyroidism.

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Other Bleeding Disorders

• Vitamin K deficiency:
  • Causes:
    • Newborns - vitamin K deficiency bleeding; all babies are offered vitamin K at birth.
    • Poor intake (critical illness, malnutrition).
    • Antibiotics.
    • Malabsorption and obstructive jaundice (fat-soluble vitamin).
  • Prolonged PT that corrects with IV vitamin K within 6–24 hours (unlike liver failure).
• Liver disease:
  • Low clotting factors, but also low natural anticoagulants ("rebalanced").
  • The INR doesn't predict bleeding well.
  • Low platelets and fibrinogen matter more.
  • See the Cirrhosis chapter.
• Acquired haemophilia A:
  • Autoantibodies against factor VIII, usually in older people, or postpartum, with cancer or autoimmune disease.
  • Sudden extensive bruising and muscle bleeds in someone with no bleeding history.
  • Isolated prolonged APTT that doesn't correct with mixing.
  • Haematology emergency - bypassing agents and immunosuppression (steroids, rituximab).
• Platelet function disorders:
  • Drugs - aspirin, clopidogrel, NSAIDs, SSRIs.
  • Uraemia (desmopressin helps).
  • Inherited (rare) - Glanzmann thrombasthenia, Bernard–Soulier syndrome.
• Vessel wall and connective tissue:
  • Senile purpura (older skin).
  • Steroid use.
  • Scurvy (vitamin C - perifollicular bleeding, gum bleeding).
  • Ehlers–Danlos syndrome.
  • Hereditary haemorrhagic telangiectasia.
  • Amyloidosis (periorbital purpura).
  • IgA vasculitis (palpable purpura on the legs and buttocks).
• Non-accidental injury - consider in children and vulnerable adults with unexplained bruising.

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Diagnosing DVT

Risk factors for VTE:

• Recent surgery (especially orthopaedic), hospital admission, immobility, long travel.
• Active cancer and chemotherapy.
• Pregnancy and the postpartum period; the combined pill and HRT (oral).
• Previous VTE; family history; thrombophilia.
• Obesity; older age.
• IBD; nephrotic syndrome; infection (including COVID-19).
• Central lines.

Assessment of suspected DVT (NICE NG158):

• Symptoms: Unilateral leg swelling, pain, tenderness, warmth, pitting oedema, dilated veins.
• Two-level DVT Wells score:
  • DVT likely (2 or more) - proximal leg vein ultrasound within 4 hours. If not possible, do a D-dimer and give an interim anticoagulant (e.g. apixaban or rivaroxaban) while waiting for a scan within 24 hours.
  • DVT unlikely (1 or less) - D-dimer. If positive, ultrasound; if negative, consider other diagnoses.
  • If ultrasound is negative but D-dimer positive and DVT is likely - repeat ultrasound in 6–8 days.
• D-dimer is sensitive but not specific - raised in older age, pregnancy, infection, cancer and after surgery. An age-adjusted threshold can be used for people over 50.
• Differential diagnosis: Cellulitis, ruptured Baker's cyst, muscle injury, lymphoedema, heart failure, superficial thrombophlebitis.
• Pulmonary embolism - see the Respiratory Emergencies and Pulmonary Vascular chapters.

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Treating Venous Thromboembolism

Choice of anticoagulant (NICE NG158):

• Apixaban or rivaroxaban first line (no initial heparin needed):
  • Apixaban 10 mg twice daily for 7 days, then 5 mg twice daily.
  • Rivaroxaban 15 mg twice daily for 21 days, then 20 mg once daily (with food).
• Alternatives: LMWH for at least 5 days followed by dabigatran or edoxaban; or LMWH with warfarin (until INR is 2 or more for 2 days).
• LMWH is preferred or required in:
  • Pregnancy.
  • Severe kidney failure (or unfractionated heparin).
  • Extremes of body weight (check levels).
  • Some cancers (e.g. GI or urothelial with high bleeding risk).
  • Significant drug interactions.
• Warfarin (INR target 2.5) for antiphospholipid syndrome, mechanical valves, and when DOACs are unsuitable (e.g. creatinine clearance under 15 mL/min).

How long to treat:

• Provoked VTE (clear temporary risk factor such as surgery): 3 months (3–6 months for proximal DVT or PE).
• Unprovoked VTE: 3 months, then consider long-term anticoagulation if the bleeding risk is low - balance recurrence risk (about 10% in the first year after stopping) against bleeding risk (e.g. using ORBIT), and the patient's preference.
• Cancer-associated VTE: 3–6 months or longer while the cancer is active.
• Recurrent VTE: Usually long-term.
• Review at 3 months, then at least yearly if long-term.

Other points:

• Don't routinely screen for cancer after unprovoked VTE beyond history, examination and basic tests (FBC, U&E, LFTs, calcium, urinalysis, chest X-ray if indicated) - NICE 2020.
• Thrombophilia testing is not routine (see below).
• Compression stockings aren't recommended routinely to prevent post-thrombotic syndrome; use them for symptoms.
• IVC filters only if anticoagulation is contraindicated in acute VTE (remove later).
• Distal (calf) DVT - treat if symptomatic, or repeat the scan at 1 week to check for extension.
• Superficial vein thrombosis - NSAIDs and compression. Fondaparinux 2.5 mg daily for 45 days if 5 cm or longer, or near the saphenofemoral junction (within 3 cm - then scan, as it may need full treatment).

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VTE in Special Situations

• Cancer-associated thrombosis:
  • DOAC (apixaban, rivaroxaban, edoxaban) or LMWH.
  • Use LMWH where there is high GI or urinary bleeding risk, or interactions with chemotherapy.
  • Continue while the cancer is active.
• Pregnancy and postpartum:
  • LMWH (weight-based dose) for the rest of pregnancy and at least 6 weeks postpartum (3 months total minimum).
  • DOACs and warfarin are avoided in pregnancy.
  • Warfarin and LMWH are safe in breastfeeding.
  • Plan delivery around LMWH (epidural timing).
• Kidney impairment:
  • Calculate creatinine clearance (Cockcroft–Gault) with actual body weight.
  • Avoid most DOACs under 15 mL/min (dabigatran under 30).
  • Use unfractionated heparin or dose-adjusted LMWH with anti-Xa monitoring.
• Unusual-site thrombosis:
  • Cerebral venous sinus (see the Stroke chapter).
  • Splanchnic veins (portal, mesenteric, hepatic).
  • Test for myeloproliferative neoplasms (JAK2) and PNH, as well as antiphospholipid syndrome.
• Upper limb DVT:
  • Usually linked to central lines or pacemaker leads, or cancer.
  • Paget–Schroetter syndrome - effort thrombosis in young athletes (thoracic outlet).
  • Treat for 3 months; a line can stay in if it is needed and working.
• Older and frail patients: Falls alone are not a reason to withhold anticoagulation; review doses with weight and kidney function.

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Preventing VTE in Hospital

Hospital-acquired thrombosis is a major preventable cause of death (NICE NG89).

• Assess every patient on admission (and when their condition changes) for VTE risk and bleeding risk.
• Medical patients:
  • LMWH (e.g. enoxaparin 40 mg once daily; 20 mg if creatinine clearance is under 30), or fondaparinux, for at least 7 days if risk outweighs bleeding risk.
  • Encourage mobilisation and hydration.
• Surgical patients:
  • Mechanical prophylaxis (anti-embolism stockings or intermittent pneumatic compression) plus LMWH as appropriate.
  • Extended prophylaxis:
    • Hip replacement - LMWH for 10 days then aspirin for 28 days, or LMWH or a DOAC for 28–35 days.
    • Knee replacement - aspirin for 14 days, or LMWH or a DOAC.
    • Major cancer surgery in the abdomen or pelvis - LMWH for 28 days.
• Stroke patients: Intermittent pneumatic compression (not stockings) for immobile patients.
• Lower limb plaster casts: Consider LMWH while immobilised.
• Pregnancy: RCOG risk assessment antenatally and postnatally.
• Contraindications to LMWH:
  • Active bleeding.
  • Platelets under 50.
  • Recent brain or eye surgery.
  • Severe uncontrolled hypertension.
  • Bleeding disorders.
  • Spinal procedures within certain timeframes.
• Stockings are contraindicated in peripheral arterial disease, severe neuropathy and leg ulcers.

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Thrombophilia and Antiphospholipid Syndrome

Inherited thrombophilias:

• Factor V Leiden - the commonest (about 5% of white Europeans); modest increase in risk.
• Prothrombin gene mutation (G20210A).
• Protein C, protein S and antithrombin deficiency - rarer, higher risk. Protein C deficiency can cause warfarin-induced skin necrosis.

When to test (NICE NG158 and BSH) - not routinely:

• Don't test people with provoked VTE, or those who will continue anticoagulation anyway - results rarely change management.
• Consider antiphospholipid antibody testing in unprovoked VTE if stopping anticoagulation is planned (it changes treatment).
• Consider hereditary testing in unprovoked VTE with a first-degree relative who has had VTE, if stopping anticoagulation is planned.
• Don't test during acute thrombosis or on anticoagulants (results are unreliable).

Antiphospholipid syndrome (APS):

• Clinical features:
  • Venous or arterial thrombosis (stroke at a young age).
  • Pregnancy complications - recurrent early miscarriage, late fetal loss, severe pre-eclampsia, placental insufficiency.
  • Livedo reticularis; low platelets; heart valve lesions.
• Laboratory criteria: Lupus anticoagulant, anticardiolipin, or anti-beta2 glycoprotein I antibodies - positive on two occasions at least 12 weeks apart.
• Primary or secondary (with SLE).
• Treatment:
  • Warfarin long-term after thrombosis (INR 2–3; higher for some arterial events).
  • DOACs are not recommended, especially in "triple-positive" APS or arterial disease (more clots).
  • Pregnancy: Low-dose aspirin plus LMWH (prophylactic or treatment dose depending on history); stop warfarin before 6 weeks.
• Catastrophic APS: Rapid multi-organ thrombosis - ICU, anticoagulation, steroids, plasma exchange or IVIg.

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Using Anticoagulants Safely

Safety checklist for DOACs:

• Calculate creatinine clearance (Cockcroft–Gault, actual body weight) - don't rely on eGFR alone, especially in older or underweight patients.
• Correct dose for the indication - under-dosing is common and increases stroke risk.
• Interactions - avoid with strong enzyme inducers (rifampicin, carbamazepine, phenytoin, St John's wort) and some HIV and antifungal drugs. Caution with other drugs that increase bleeding (NSAIDs, SSRIs, antiplatelets).
• Check FBC, U&E and LFTs at least yearly (more often in kidney impairment or older age).
• Educate patients - adherence (short half-life), missed doses, alert card, bleeding signs.

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Bleeding on Anticoagulants

• All major bleeding:
  • Resuscitate; stop the anticoagulant.
  • Note the time of the last dose; check FBC, clotting and kidney function.
  • Tranexamic acid (except in GI bleeding, where it doesn't help and raises VTE risk).
  • Treat the source (endoscopy, surgery, embolisation).
• Warfarin:
  • Major bleeding - prothrombin complex concentrate (PCC, e.g. 25–50 units/kg) plus IV vitamin K 5–10 mg. FFP only if PCC isn't available.
  • INR over 8, no bleeding - stop warfarin; oral vitamin K 1–5 mg; restart when INR is under 5.
  • INR 5–8, no bleeding - withhold 1–2 doses and reduce the maintenance dose. Minor bleeding - also give IV vitamin K 1–3 mg.
  • Find the cause of the high INR (interactions, illness, alcohol, diet).
• Dabigatran - idarucizumab (specific antidote) for life-threatening bleeding or urgent surgery; haemodialysis can remove it.
• Factor Xa inhibitors (apixaban, rivaroxaban, edoxaban):
  • Andexanet alfa - NICE recommends it only for life-threatening GI bleeding on apixaban or rivaroxaban (TA697).
  • Otherwise use PCC (off-label).
  • Activated charcoal if taken within 2–6 hours.
• Heparin - protamine fully reverses unfractionated heparin and partly reverses LMWH.
• Restarting:
  • Restart when bleeding is controlled and the indication is strong (e.g. AF with high stroke risk) - often within 1–2 weeks after GI bleeding.
  • Longer after intracranial haemorrhage (specialist decision).
  • Stopping permanently often carries more risk than restarting.
• See the Haematological Emergencies and Stroke chapters for major haemorrhage and anticoagulant-related brain bleeds.

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Antiplatelet Drugs and Bleeding

• Aspirin - irreversible COX inhibition; the effect lasts the platelet lifespan (7–10 days).
• P2Y12 inhibitors - clopidogrel, prasugrel (irreversible), ticagrelor (reversible; also causes breathlessness).
• Dual antiplatelet therapy after ACS or stents - duration decided by cardiology; adding an anticoagulant ("triple therapy") greatly raises bleeding risk, so keep it short.
• Gastroprotection - PPI for people on antiplatelets with GI risk factors (lansoprazole or pantoprazole with clopidogrel).
• Before procedures - see the GI Investigations and Cardiology Special Situations chapters. Never stop antiplatelets after a recent stent without cardiology advice.
• Bleeding on antiplatelets: Stop if possible; platelet transfusion only for life-threatening bleeding or neurosurgery (limited evidence; it can be harmful in ICH on antiplatelets unless surgery is needed).

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Drug Reference Table

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Spot the Diagnosis

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Exam-style Scenarios

1. A 56-year-old has a swollen right calf. Wells score is 3. Ultrasound can't be done until tomorrow.
Answer: DVT likely.

• D-dimer and an interim anticoagulant (e.g. apixaban 10 mg twice daily).
• Proximal leg ultrasound within 24 hours.
• If confirmed: continue apixaban; decide duration based on whether it was provoked.

2. A 45-year-old has a first unprovoked PE. After 3 months of apixaban she is well. Bleeding risk is low.
Answer: Consider long-term anticoagulation.

• Discuss recurrence vs bleeding risk.
• Consider antiphospholipid antibody testing if stopping is being considered.
• If continuing: apixaban 5 mg (or 2.5 mg) twice daily long-term, with yearly review.

3. A 70-year-old on day 8 of IV unfractionated heparin after cardiac surgery has platelets 60 (from 250) and a new arterial clot in the leg.
Answer: High 4Ts score - HIT with thrombosis.

• Stop all heparin (including flushes); start argatroban; send anti-PF4 antibodies.
• No platelet transfusion; no warfarin until platelets recover.
• Vascular surgery review; record heparin allergy.

4. An 82-year-old on warfarin for AF has a large GI bleed. INR is 4.2.
Answer: Major bleeding on warfarin.

• Resuscitate; stop warfarin.
• PCC plus IV vitamin K 5–10 mg; urgent endoscopy.
• Plan to restart anticoagulation once bleeding is controlled (consider a DOAC at the correct dose).

5. A 30-year-old woman has platelets of 15 × 10⁹/L, petechiae and gum bleeding. FBC and film are otherwise normal.
Answer: Probable ITP.

• Test HIV, hepatitis C, H. pylori; check for SLE and pregnancy.
• Prednisolone 1 mg/kg or dexamethasone 40 mg for 4 days; IVIg if bleeding significantly.
• Avoid NSAIDs; second-line TPO receptor agonists if it persists.

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Key Points

• Platelet-type bleeding affects skin and mucosa; factor-type bleeding affects joints and muscles.
• Isolated prolonged APTT: heparin, haemophilia, VWD, lupus anticoagulant. Isolated prolonged PT: warfarin, vitamin K deficiency, liver disease.
• Exclude platelet clumping before diagnosing thrombocytopenia; schistocytes with low platelets means think TTP.
• ITP: isolated low platelets; treat bleeding or very low counts - steroids, IVIg, then TPO receptor agonists.
• HIT: platelets fall over 50% at 5–10 days with thrombosis - stop all heparin, start a non-heparin anticoagulant, no platelets.
• Haemophilia: X-linked; give factor first, then image; avoid IM injections and NSAIDs.
• VWD is the commonest inherited bleeding disorder - think of it in heavy periods.
• Suspected DVT: Wells score, then ultrasound within 4 hours (or interim DOAC) or D-dimer.
• Apixaban or rivaroxaban first line for VTE; LMWH in pregnancy; warfarin for APS and mechanical valves.
• Provoked VTE: 3 months. Unprovoked: consider long-term if bleeding risk is low.
• Don't screen routinely for cancer or thrombophilia after VTE.
• Calculate creatinine clearance and use the correct DOAC dose - check interactions.
• Warfarin major bleed: PCC plus IV vitamin K. Dabigatran: idarucizumab. Xa inhibitors: PCC, or andexanet for GI bleeds.
• Assess every inpatient for VTE and bleeding risk.