Deep Vein Thrombosis (DVT)

Question 1

Define DVT and summarise its aetiology and epidemiology

Answer 1

Defintion: Formation of a thrombus within the deep veins (most commonly calf or thigh)

Aetiology/Risk factors of DVTs:
- Deep veins in the legs are more prone to blood stasis, hence clots are more likely to form (look up Virchow's triad)
- Risk Factors:
  • COCP
  • Post-surgery
  • Prolonged immobility
  • Obesity
  • Pregnancy 
  • Dehydration 
  • Smoking
  • Polycythaemia 
  • Thrombophilia (e.g. protein C deficiency)
  • Malignancy

Summarise the epidemiology of DVT
- Very common (especially in hospitalized patients)

Question 2

Describe the history/presenting symptoms of DVTs

Answer 2

• Swollen, painful limb

- Can also be painless

Question 3

What are the signs of DVTs upon physical examination?

Answer 3

- Examination of the leg 
  • Local erythema, warmth and swelling
  • Measure the leg circumference
  • Varicosities 
  • Skin colour changes
  • Homan's sign- forced passive dorsiflexion of the ankle causes deep pain

• Risk is stratified using the WELLS criteria
  • Score 2 or more = high risk
• Examine for PE:
  • Check resp rate, pulse oximetry and pulse rate

Question 4

What investigations are used to identify DVTs?

Answer 4

• Doppler Ultrasounds- Gold standard
• Impedance Plethysmography- changes in blood volume results in changes of electrical resistance
• Bloods:
  • D-dimer: can be used as a negative predicator
  • Thrombophilia screen if indicated
• If PE suspected
  • ECG
  • CXR
  • ABG

Question 5

How are DVTs managed?

Answer 5

• Anticoagulation:
  • Heparin whilst waiting for warfarin to increase INR to the target range of 2-3
  • DVTs that do NOT extend above the knee may be observed and anticoagulated for 3 months
  • DVTs extending beyond the knee require anticoagulation for 6 months
  • Recurrent DVTs require long-term warfarin
• IVC Filter
  • May be used if anticoagulation is contraindicated
• Prevention
  • Graduated compression stockings
  • Mobilistation
  • Prophylactic heparin (if high risk e.g. hospitalized patients)

Question 6

What are the complications of DVTs?

Answer 6

• PE
• Venous infarction (phlegmasia cerulean dolens)
• Thrombophlebitis (results from recurrent DVT)
• Chronic venous insufficiency

Question 7

Summarise the prognosis for patients with DVTs

Answer 7

• Dependent on extent of DVT
• Below- knew DVTs have good prognosis
• Proximal DVTs have a greater risk of embolisation