12. Venous Thromboembolism - DVT + PE

Question 1

What is thrombosis?

Answer 1

Defined as a solid mass formed IN the circulation from the constituents of the blood during life - essentially it is a clot within a blood vessel - a thrombus

Question 2

What is deep vein thrombosis (DVT)?

Answer 2

Thrombus in the venous circulation:
* Low pressure and fibrin rich

Question 3

What is the difference between venous thrombosis and arterial thrombosis?

Answer 3

Unlike arterial thrombosis occurs in normal vessels, DVT often in the deep veins of the leg.

Question 4

How would you describe a venous thrombosis?

Answer 4

Fibrin rich - a ‘red thrombosis’.

Question 5

Give 3 causes of DVT.

Answer 5

Surgery, immobility, leg fracture, oral contraceptive pill, long haul
flights, malignancy

Question 6

Give 5 risk factors for DVT.

Answer 6

1. Surgery, immobility, leg fracture.
2. OCP, HRT.
3. Long haul flights.
4. Genetic predisposition.
5. Pregnancy.
6. Increasing age.

Question 7

What are the symptoms of DVT?

Answer 7

May be asymptomatic.

• Pain in the calf, often with swelling, redness and engorged superficial veins.
• Warmth in affected calf.
• Maybe ankle oedema.
• With complete occlusion, particularly in a large vein can result in cyanotic discolouration of the limb and severe oedema.

Question 8

Briefly describe the investigations might be done in order to diagnose a DVT.

Answer 8

1. D-dimer (looks for fibrin breakdown products)
   - If normal, you can exclude DVT.
   Abnormal does not confirm diagnosis however.
2. Ultrasound compression scan
   - Find the popliteal vein.
   - If you can squash it shut = no DVT
   - if you can’t squash the vein = clot = DVT.
3. Venography
4. Doppler ultrasound

FIRST: Well’s score for DVT
<2 = unlikely -> D-dimer
>2 = likely -> then Doppler ultrasound

Question 9

What is the treatment for DVT?

Answer 9

1. LMWH.
2. Oral warfarin or DOAC.
3. Compression stockings.
4. Treat the underlying cause e.g. malignancy or thrombophilia.

Question 10

How does LMWH work?

Answer 10

It activates anti-thrombin, which then inhibits thrombin and factor 10a.

Question 11

How does warfarin work?

Answer 11

It produces NON-functional clotting factors 2, 7, 9 and 10.

Question 12

What is warfarin the antagonist of?

Answer 12

Vitamin K.

Question 13

Why is warfarin difficult to use?

Answer 13

1. Lots of interactions!
2. Teratogenic.
3. Needs almost constant monitoring.

Question 14

How can DVT’s be prevented?

Answer 14

1. Hydration.
2. Mobilisation.
3. Compression stockings.
4. Low dose of LMWH.

Question 15

What might be the consequence of a dislodged DVT?

Answer 15

Pulmonary embolism.