Venous thrombosis


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Lecture note on venous thrombosis prepared with reference of surgical text books

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Venous thrombosis

  1. 1. Bailey & Love-Short practice of Surgery.25th Venous Thrombosis “Formation of a semi-solid coagulum within flowing blood in the venous system.” Could be any where: cavernous, azygous, mesenteric, iliac, LL deep vein Complication Immediate risk of pulmonary embolus→ sudden death. post-thrombotic limb→ venous ulceration. Aetiology 1. changes in the vessel wall (endothelial damage); 2. stasis, which is diminished blood flow through the veins; 3. coagulability of blood (thrombophilia). Risk factors for VT Patient factors 1. Age 2. Obesity 3. Varicose veins 4. Immobility 5. Pregnancy 6. Puerperium 7. High-dose oestrogen therapy 8. Previous DVT or PE 9. Thrombophilia Disease or surgical procedure 1. Trauma or surgery, especially of pelvis, hip and lower limb 2. Malignancy, especially pelvic, and abdominal metastatic 3. Heart failure 4. Recent MI 5. Paralysis of lower limb(s) 6. Infection 7. IBD 8. Nephrotic syndrome 9. Polycythaemia 10. Paraproteinaemia 11. PNH antibody or lupus anticoagulant 12. Behçet’s disease 13. Homocystinaemia Abnormalities of thrombosis and fibrinolysis that lead to an ↑ risk of venous thrombosis Congenital 1. Deficiency of anti-thrombin III, protein C or protein S 2. Antiphospholipid antibody or lupus anticoagulant 3. Factor V Leiden gene defect or activated protein C resistance 4. Dysfibrinogenaemias Acquired 1. Antiphospholipid antibody or lupus anticoagulant ‘e-thrombosis’:blood clots occurring in people sitting at their computers for long periods of time.
  2. 2. Bailey & Love-Short practice of Surgery.25th A thrombus often develops in the soleal veins of the calf. Thrombus→ totally occlude perfusion to all or part of one or both lungs (PE). Acute right heart obstruction →sudden collapse and death. Lung infarction is rare as the lung has a dual blood supply (bronchial and pulmonary arteries). Moderately sized emboli can cause pyramidal shaped infarcts. Diagnosis 1. Pain and swelling, especially in the calf of one lower limb. 2. Mild pitting oedema of the ankle, 3. Dilated surface veins, 4. Stiff calf 5. Tenderness over the course of the deep veins 6. Low-grade pyrexia: especially in repeated PE. B/L DVT - DD Causes of systemic oedema hypoproteinaemia renal failure heart failure. Asymptomatic + signs of a PE e.g. pleuritic chest pain, haemoptysis and SOB Other 1. cellulitic 2. white or cyanosed: phlegmasia alba dolens & phlegmasia cerulia dolens 3. If venous gangrene → they often have an underlying neoplasm. Homans’ sign – resistance (not pain) of the calf muscles to forcible dorsiflexion →outdated If having PE causing right heart strain i. Signs of cyanosis ii. Dyspnoea iii. Raised neck veins iv. A fixed split S2 v. Pleural rub Investigation D-dimer→ if ↑, a duplex USS of the deep veins should be performed. Presence of a thrombosis Filling defects in flow lack of compressibility 1. Ventilation–perfusion scanning→ mismatched defects 2. CT scanning of the pulmonary arteries→ filling defects in the pulmonary arteries Rarely required Ascending venography Pulmonary angiography DD-DVT 1. Ruptured Baker’s cyst 2. Calf muscle haematoma 3. Ruptured plantaris muscle
  3. 3. Bailey & Love-Short practice of Surgery.25th 4. Thrombosed popliteal aneurysm 5. Arterial ischaemia. DD-PE 1. MI 2. pleurisy 3. Pneumonia. Prophylaxis Grade as low,moderate or high risk. Low-risk o Young o Minor illnesses o Operations lasting 30 min or less Moderate o Age >40 o Debilitating illness o Major surgery Highrisk o Age >40 o Serious medical conditions: stroke/MI o Major surgery with an additional risk factor: H/O VTE or known malignant disease. Mechanical 1. Graduated elastic compression stockings 2. External pneumatic compression Pharmacological (More effective than mechanical methods at reducing the risk of thrombosis) LMWH S/C –dose-wt i. Does not require monitoring ii. ↓Risk of heparin-induced thrombocytopenia iii. Can be given once a day iv. Lower risk of bleeding complications. UFH, warfarin: rarely Treatment S/C LWMH Warfarin (D1-10mg, D2-10mg, D3-5mg, D3-PT for maitainance dose guidance) Thrombolysis: tPA Stent grafting: ‘iliac vein compression syndrome’ Venous thrombectomy +AV fistula: iliac veins Rx-PE Anticoagulation Observation Severe right heart strain+SOB→ fibrinolytic treatment. Rarely-cardiac arrest →surgical pulmonary embolectomy. Prophylaxis against PE I o Filters (vena cava filter-Greenfield filter) 1. High risk of embolism 2. When anticoagulants are contraindicated 3. Pts who continue to have PE despite adequate anticoagulation.
  4. 4. Bailey & Love-Short practice of Surgery.25th Superficial thrombophlebitis Common causes i. External trauma (especially to varicose veins), ii. Venepunctures iii. Infusions of hyperosmolar solutions & drugs iv. The presence of an iv cannula for > 24–48 hrs v. coagulation disorders a. polycythaemia, b. thrombocytosis c. sickle cell disease Some systemic diseases Buerger’s disease Malignancy, esp. pancreas ↓ Flitting thrombophlebitis (thrombophlebitis migrans) ↓ affecting different veins at different times. C/F Vein→ solid & tender Skin→ may be attached to the vein Erythematous → brown. A linear segment of vein of variable length can be easily palpated once the Inflammation has died down. Ix FBC Coagulation screen Duplex scan Malignancy: endoscopy, imaging: abdominal CT scan. Rx Mostly:NSAIDs and the condition resolves spontaneously. Incision or excision of infected thrombi:rare Ligation to prevent propagation into the deep veins is almost never required. Anticoagulation: associated dvt or thrombophilias