Deep Vein Thrombosis

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.

Pathophysiology

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

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 features	Score
Active cancer	1
Paralysis, paresis, or recent cast immobilization of the lower extremities	1
Recently bedridden for ≥ 3 days, or major surgery within the previous 12 weeks requiring general or regional anesthesia	1
Localized tenderness along the distribution of the deep venous system	1
Entire leg swelling	1
Calf swelling at least 3 cm larger than that on the asymptomatic side	1
Pitting edema confined to the symptomatic leg	1
Collateral superficial veins (non-varicose)	1
Previously documented deep vein thrombosis	1
Alternative diagnosis at least as likely as deep vein thrombosis	2

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

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 situation	Duration
VTE provoked by transient major risk factor	3 months
Distal unprovoked DVT or PE	3 months
First unprovoked proximal DVT or PE	6 months
First unprovoked VTE plusActive malignancyMultiple thrombophiliasAntiphospholipid syndrome	Indefinite
Recurrent unprovoked VTE	Indefinite

Complications & Prognosis

Complications

• Acute
  • Pulmonary Embolism 
  • Phlegmasia cerulea dolens (acute limb gangrene)
• 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