Deep Vein Thrombosis and Pulmonary Thromboembolism

Question 1

What is the incidence of DVT?

Answer 1

1 in 1000 per annum

Question 2

What is the case fatality rate of venous thromboembolism?

Answer 2

1-5%

Question 3

What is the incidence of PE?

Answer 3

3000-5000 per annum

Question 4

What percentage of autopsies reveal a PE?

Answer 4

20% of autopsies

Question 5

What are the components of Virchow’s Triad?

Answer 5

Stasis
Vessel damage
Hypercoagulability

Question 6

What are examples of presentations of venous thromboembolism?

Answer 6

Limb DVT
Pulmonary embolism
Visceral venous thrombosis
Intracranial venous thrombosis 
Superficial thrombophlebitis

Question 7

What are the features of venous thrombus?

Answer 7

Red thrombus - fibrin and red cells
Results in back pressure
Principally due to stasis and hypercoagulability

Question 8

What are the features of arterial thrombus?

Answer 8

White clot - platelets and fibrin
Results in ischaemia and infarction
Principally secondary to atherosclerosis

Question 9

What is the presentation of DVT?

Answer 9

Unilateral limb swelling 
Persisting discomfort
Calf tenderness
Warmth 
Erythema
May also be clinically silent

Question 10

What are the potential long-term consequences of DVT?

Answer 10

Post-phlebitic syndromes

e.g. swelling, discomfort, pigmentation, ulceration

Question 11

What is the presentation of PE?

Answer 11

Pleuritic chest pain
Dyspnoea
Haemoptysis 
Tachycardia
Pleural rub on auscultation

Question 12

What is the presentation of massive PE?

Answer 12

Severe dyspnoea of sudden onset
Collapse 
Central cyanosis
Tachycardia
Hypotension 
Raised JVP 
Altered heart sounds
May cause sudden death

Question 13

What are the potential long-term consequences of PE?

Answer 13

Most recover fully

May result in pulmonary hypertension

Question 14

What are the risk factors for venous thromboembolism?

Answer 14

Increasing age
Tissue trauma
Immobility 
Obesity 
Smoking 
Systemic disease e.g. cancer
Genetics e.g. heritable thrombophilia
Pregnancy 
Exogenous oestrogen e.g. OCP, HRT

Question 15

What is the most prevalent heritable thrombophilia?

Answer 15

Factor V Leiden

Question 16

What is the link between VTE and travel?

Answer 16

Relative risk increased by 2-3

Increased risk in short, tall or overweight people, and in women on the OCP

Question 17

How is DVT diagnosed?

Answer 17

Clinical assessment
D-dimer
Compression ultrasound

Question 18

How is a d-dimer test useful?

Answer 18

Negative result is more useful as it will rule out DVT

Positive result will not confirm DVT but will indicate need for more investigation

Question 19

How is PE diagnosed?

Answer 19

Clinical assessment
D-dimer in unlikely patients
Isotope ventilation/perfusion scan
CT pulmonary angiogram

Question 20

How can VTE be prevented in hospital?

Answer 20

Early mobilisation
Anti-embolism stockings
Daily injections of low molecular weight heparin

Question 21

What pressures are provided by anti-embolism stockings?

Answer 21

18mmHg at the ankle
14mmHg at the mid-calf
8mmHg at the upper thigh

Result in maximal femoral blood flow velocity of 139% of the baseline

Question 22

When are graduated compression stockings useful?

Answer 22

Prevention of DVT
Chronic venous insufficiency 
Varicose veins
Oedema
Lymphoedema 
Prevention of post-phlebitic syndrome

Question 23

What is the treatment of VTE?

Answer 23

Low molecular weight heparin for 5 or more days then oral anticoagulant (warfarin) for at least 3 months
Thrombolysis for massive PE
Vena caval filter