Deep vein thrombosis

Question 1

Define:

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 (look up Virchow’s triad)

Question 3

Risk factors:

Answer 3

o	Age 
o	OCP (synthetic oestrogen)
o	Post-surgery
o	Prolonged immobility – ASK ABOUT TRAVEL
o	Obesity 
o	Pregnancy 
o	Dehydration 
o	Smoking 
o	Polycythaemia 
o	Thrombophilia (e.g. protein C deficiency) 
o	Malignancy
o	Trauma 
o	Past DVT

Question 4

Epidemiology:

Answer 4

• VERY COMMON

* Especially in hospitalised patients

Question 5

Symptoms:

Answer 5

• Swollen limb
• May be painless or painful
• Mild fever

Question 6

Signs:

Answer 6

• Examination of the Leg
o Local erythema, warmth and swelling, tenderness
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
o Pitting oedema

• Mild fever

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

Question 7

Investigations:

Answer 7

•	First: calculate Well’s score. If score less than or equal to 2: do D-dimer
o	If D-dimer is normal: DVT excluded
o	If D-dimer elevated: do duplex USS
•	If Well’s score >2: do duplex USS
•	If pregnant: do duplex USS straight away
•	Doppler Ultrasound - GOLD STANDARD 
•	If PE suspected
o	ECG 
o	CXR 
o	ABG

Question 8

Management:

Answer 8

• ANTICOAGULATION
o Heparin (LMWH) whilst waiting for warfarin to increase INR to the target range of 2-3. This is because warfarin is prothrombotic for first 48 hours, so must be given with heparin.
o Can use NOAC instead of warfarin
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 pulmonary embolisation

Prevention
o Graduated compression stockings – prevent long term complications like pain and swelling
o Mobilisation
o Prophylactic heparin (if high risk e.g. hospitalised patients)

Question 9

Complications:

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