Deep Vein Thrombosis

Question 1

Define

Answer 1

DEFINITION: formation of a thrombus within the deep veins (most commonly in the calf or thigh)

Question 2

Causes

Answer 2

Deep veins in the legs are more prone to blood stasis, hence clots are more likely to form (look up Virchow’s triad)

Question 3

Risk factors

Answer 3

COCP

Post-surgery

Prolonged immobility

Obesity

Pregnancy

Dehydration

Smoking

Polycythaemia

Thrombophilia (e.g. protein C deficiency)

Malignancy

Question 4

Epidemiology

Answer 4

VERY COMMON

Especially in hospitalised patients

Question 5

Symptoms

Answer 5

Swollen limb

May be painless

Question 6

Signs

Answer 6

Examination of the Leg

• Local erythema, warmth and swelling
• Measure the leg circumference
• Varicosities (swollen/tortuous vessels)
• Skin colour changes

NOTE: Homan’s Sign - forced passive dorsiflexion of the ankle causes deep calf pain

Risk is stratified using the WELLS CRITERIA (NOTE: this is different from the PE Wells criteria)
-Score 2 or more = high risk

Examine for PE
-Check respiratory rate, pulse oximetry and pulse rate

Question 7

Investigations

Answer 7

Doppler Ultrasound - GOLD STANDARD

Impedance Plethysmography - changes in blood volume results in changes of electrical resistance

Bloods

• D-dimer: can be used as a negative predictor
• Thrombophilia screen if indicated

If PE suspected

• ECG
• CXR
• ABG

Question 8

Management

Answer 8

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 and there is a risk of embolisation

Prevention

• Graduated compression stockings
• Mobilisation
• Prophylactic heparin (if high risk e.g. hospitalised patients)

Question 9

Complication

Answer 9

PE

Venous infarction (phlegmasia cerulea dolens)

Thrombophlebitis (results from recurrent DVT)

Chronic venous insufficiency

Question 10

Prognosis

Answer 10

Depends on extent of DVT

Below-knee DVTs have a GOOD prognosis

Proximal DVTs have a greater risk of embolisation