Deep Vein Thrombosis

Question 1

Definition

Answer 1

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

Question 2

Aetiology

Answer 2

Deep veins in the legs are more prone to blood stasis, hence clots are more likely to form

Vrichow Triad (3 factors important in the development of venous thrombosis)

• venous stasis
• activation of blood coagulation
• vein damage/endothelial injury

Question 3

Risk factors

Answer 3

o Combined oral contraceptive pill
o Post-surgery
o Prolonged immobility
o Obesity
o Pregnancy
o Dehydration
o Smoking
o Polycythaemia
o Thrombophilia (e.g. protein C deficiency)
o Malignancy

Question 4

Epidemiology

Answer 4

· VERY COMMON

· Especially in hospitalised patients

Question 5

Presenting symptoms

Answer 5

· Swollen limb

· May be painless

Question 6

Signs on physical examination (leg)

Answer 6

· Examination of the Leg

o Local erythema, warmth and swelling
o Measure the leg circumference
o Varicosities (swollen/tortuous vessels)
o Skin colour changes
o NOTE: Homan’s Sign - forced passive dorsiflexion of the ankle causes deep calf pain

Question 7

Signs on physical examination (other)

Answer 7

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

· Examine for PE
o Check respiratory rate, pulse oximetry and pulse rate

Question 8

Investigations

Answer 8

· Doppler Ultrasound - GOLD STANDARD

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

· Bloods
o D-dimer: can be used as a negative predictor
o Thrombophilia screen if indicated

· If PE suspected
o ECG
o CXR
o ABG

Question 9

Management plan (anti-coagulation)

Answer 9

· ANTICOAGULATION

o Heparin whilst waiting for warfarin to increase INR to the target range of 2-3
o DVTs that do NOT extend above the knee may be observed and anticoagulated for 3 months
o DVTs extending beyond the knee require anticoagulation for 6 months
o Recurrent DVTs require long-term warfarin

· IVC Filter

o May be used if anticoagulation is contraindicated and there is a risk of embolisation

Question 10

Management plan (prevention)

Answer 10

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

Question 11

Possible complications

Answer 11

· PE
· Venous infarction (phlegmasia cerulea dolens)
· Thrombophlebitis (results from recurrent DVT)
· Chronic venous insufficiency

Question 12

Prognosis

Answer 12

· Depends on extent of DVT
· Below-knee DVTs have a GOOD prognosis
· Proximal DVTs have a greater risk of embolisation