Cardiovascular: Deep Vein Thrombosis (DVT)

Question 1

what is a DVT?

Answer 1

Deep vein thrombosis (DVT) is the formation of a thrombus (blood clot) in a deep vein, usually in the legs, which partially or completely obstructs blood flow. A DVT is caused by anything that impedes normal venous return.

Question 2

what are some risk factors for a DVT?

Answer 2

• Previous venous thromboembolism.
• Cancer (known or undiagnosed).
• Increasing age (60 and over).
• Obesity.
• Male.
• Heart failure.
• Thrombophilia.
• Chronic low-grade injury to the vascular wall (for example vasculitis, hypoxia from venous stasis, or chemotherapy).
• Varicose veins.
• Smoking.
• Certain gene codes – Mutations in the gene coding for factor 5 (factor V Leiden) on Chromosome 23.
• Haematological disorders e.g. polycythaemia.
• Family history of VTE (PE or DVT).
• Antiphospholipid syndrome.

Question 3

what is polycythaemia?

Answer 3

also known as erythrocytosis, means having a high concentration of red blood cells in your blood. This makes the blood thicker and less able to travel through blood vessels and organs.

Question 4

what risk factors temporarily raise the likelihood of DVT?

Answer 4

• immobility
• significant trauma
• direct trauma to a vein
• hormone treatment
• pregnancy
• dehydration

Question 5

what are some clinical features of a DVT?

Answer 5

Pain and swelling in one leg (occasionally both legs).

Tenderness, changes to skin colour and temperature, vein distention.

Question 6

which conditions present in a similar way to a DVT?

Answer 6

Physical trauma. 
Ruptured Baker’s cyst.
Cellulitis. 
Dependent oedema.
Varicose veins. 
Compartment syndrome.

Question 7

which score should be used to assess the likelihood of a DVT?

Answer 7

The two-level DVT Wells score

Question 8

for people who present likely to have a DVT (based on the results of the two-level DVT Wells score), what is the management?

Answer 8

• leg ultrasound scan to be carried out within 4 hours
• If a proximal leg vein ultrasound scan cannot be carried out within 4 hours of being requested, a blood sample should be taken for D-dimer testing; an interim 24-hour dose of a parenteral anticoagulant should be given; and a proximal leg vein ultrasound scan should be arranged (to be carried out within 24 hours of being requested).

Question 9

for people who present unlikely to have a DVT (based on the results of the two-level DVT Wells score), what is the management?

Answer 9

a blood sample should be taken for D-dimer testing:

• positive d-dimer: ultrasound within 4 hours
• negative d-dimer: consider alternative diagnosis.

Question 10

what is the d-dimer test?

Answer 10

The formation of thrombus is normally followed by an immediate fibrinolytic response, resulting in generation D-dimer into the circulation.

A negative D-dimer assay implies that thrombosis is not occurring and excludes a diagnosis of DVT (along with clinical scores and imaging).

Question 11

A positive D-dimer result can indicate thrombosis, what other possible causes of a raised D-dimer?

Answer 11

liver disease, inflammation, malignancy, pregnancy, trauma, and recent surgery.

Question 12

What is the first-line treatment for a DVT?

Answer 12

1. Anticoagulation: Rivaroxaban
2. Physical activity.
3. Gradient stockings.

Question 13

with reference to treating a DVT, you should not prescribe Rivaroxaban if the patient is on which other medications?

Answer 13

• aspirin
• clopidogrel

(Rivaroxaban increases risk of bleeding events in both)

NB: Rivaroxaban should also be avoided during pregnancy and breast feeding

Question 14

what advise would you give to a patient with a DVT after treatment?

Answer 14

• walk regularly after discharge
• elevate affected leg when sitting
• refrain from extended travel or planes for at least 2 weeks after treatment.