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Deep Vein Thrombosis

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Overview

Deep vein thrombosis (DVT) is the formation of a blood clot in a vein deep under the skin 25-50% of surgical patients and many non-surgical patients. 65% of DVT are below the knee are symptomatic and rarely embolism to the lung. There are many causes of DVT.

Definition
Thrombus: 
blood clot 
Thrombosis: 
blood clot that forms in a vessel and remains there
Deep Vein Thrombosis (DVT): 
Formation of a blood clot in one of the deep veins of the body, usually in the leg
Pulmonary Embolism (PE):
occurs most often from a disloged thrombus from teh lower limb (DVT). The embolyus travels towards the lung and becomes lodged in the pulmonary artery resulting in infarction of the lung tissue.
Venous Thromboembolism (VTE): 
Formation, development, or existence of a blood clot or thrombus within the venous system that has/potential to embolize.
Watch Deep Vein Thrombosis

Pathophysiology

All comes down to Virchow’s Triad. Any change to Virchows triad increases the risk of VTE.

Virchows Triad: Hypercoagulability, Vessel wall injury, Stasis.

Hypercoagulability

  • Malignancy
  • Surgery
  • Trauma
  • Oral contraceptive pill
  • Genetic
  • Antiphosphlipid syndrome
  • Hyper homocysteine level
Inherited Thombophilias
Factor 5 leiden mutation
Pro-thrombin gene mutation
Protein S deficiency
Protein C deficiency

Stasis

  • Immobility, e.g. after surgery
  • Pregnancy
  • Obesity
  • Heart failure
  • Cast on the leg
  • Extended travel in plane/vehicle

Endothelial injury

  • Inflammation
  • Previous thrombosis
  • Atherosclerosis
  • Fracture

Clinical Manifestation

Clinical Presention DVT usually affects the veins in the legs, notably the calf.

  • Asymmetrical pain and/or tenderness
  • Asymmetrical warmth/ erythema
  • Asymmetrical swelling

Signs of Pulmonary embolism (complication of DVT)

  • Breathlessness
  • Chest pain
  • Coughing
  • Tachycardia
  • Haemoptysis

Wells Criteria

MODIFIED WELL CRITERIA 
Clinical featuresScore
Active cancer1
Paralysis, paresis, or recent cast immobilization of the lower extremities1
Recently bedridden for ≥ 3 days, or major surgery within the previous 12 weeks requiring general or regional anesthesia1
Localized tenderness along the distribution of the deep venous system1
Entire leg swelling1
Calf swelling at least 3 cm larger than that on the asymptomatic side1
Pitting edema confined to the symptomatic leg1
Collateral superficial veins (non-varicose)1
Previously documented deep vein thrombosis1
Alternative diagnosis at least as likely as deep vein thrombosis2

Wells Scoring System – help tailor investigations

  • Low probability: 0
  • Moderate probability: 1-2
  • High probability: 3-8

Diagnosis

  • Cellulitis
  • Thrombophlebitis
  • Arthritis
  • Asymmetric peripheral oedema secondary to heart failure, renal disease or liver disease
  • Haematoma
  • Lymphoedema
  • Ruptured backers cyst
  • Varicose veins
Think D-dimer assay is only useful if it is negative; it helps in ruling out DVT.

Diagnosis

  • Duplex ultrasound
  • Venography (phlebography) – Gold standard

Treatment

The aim of treatment is to prevent PE, reduce morbidity and prevent or minimise the risk of developing the postphlebitic syndrome

  • Pain management – analgesia +/- opioids
  • Anticoagulation
    • Low risk bleeding – Low molecular weight heparin (enoxaparin 1.5mg/kg SC daily)
    • Average risk bleeding – Unfractionated heparin
MANAGEMENT DURATION
Clinical situationDuration
VTE provoked by transient major risk factor3 months
Distal unprovoked DVT or PE3 months
First unprovoked proximal DVT or PE6 months
First unprovoked VTE plusActive malignancyMultiple thrombophiliasAntiphospholipid syndromeIndefinite
Recurrent unprovoked VTEIndefinite

Complications and Prognosis

Complications

  • Acute
  • Chronic
    • Post thrombotic syndrome
    • Chronic venous insufficiency

Prognosis

Prevention

  • Identify patient at risk
  • Prevent Dehydration
  • Mechanical prophylaxis
    • Intermittent Pneumotic Compression
    • Calf compression stockings
  • Encourage movement
  • Exercise
  • Quit smoking
  • Medication – Warfarin to therapeutic dose INR 2-3 OR NOAC of choice
  • IVC filter

Prevention in surgery

  • High Risk – LMWH (40mg daily) + mechanical prophylaxis
    • Orthopaedic Surgery
    • Major trauma
    • Fracture
    • Major surgery >40yo
  • Medium Risk – LMWH (20mg daily) + mechanical prophylaxis
  • Low Risk – Consider LMWH + mechanical prophylaxis
    • All other surgery
Remember Make sure there are no contraindications for LMWH and Mechanical prophylaxis.

Discussion

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