thrombotic disoders

Question 1

What is venous thromboembolism (VTE)?

Answer 1

Venous thromboembolism (VTE) is the process of blood clot formation in the veins. It includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

Question 2

What is provoked VTE?

Answer 2

Provoked VTE refers to a VTE event that has a clear precipitating cause identified from the patient’s history or diagnostic tests

Question 3

What is unprovoked VTE?

Answer 3

Unprovoked VTE refers to a VTE event that does not have a clear cause identified from the patient’s history or diagnostic tests.

Question 4

What is thrombophilia?

Answer 4

Thrombophilia is a condition in which the blood in the body clots more easily than normal. This can increase the risk of developing blood clots, including VTE.

Question 5

What are the three components of Virchow’s triad?

Answer 5

The three components of Virchow’s triad are circulatory stasis, hypercoagulable state, and vascular injury.

Question 6

What are some causes of circulatory stasis?

Answer 6

Causes of circulatory stasis include bed rest, lower limb orthopaedic surgery, major abdominal surgery, pregnancy, and long haul flights or long car journeys.

Question 7

What are some causes of hypercoagulable states?

Answer 7

Causes of hypercoagulable states include smoking, oestrogens (oral contraceptives, HRT), active cancer, and inherited and acquired thrombophilias.

Question 8

What are some causes of vascular injury?

Answer 8

Causes of vascular injury include limb trauma including surgery, foreign bodies such as IV cannulae and pacemaker wires, sepsis, bacteria and toxins, previous DVT, and May Thurner Syndrome.

Question 9

What is venous thromboembolism (VTE)?

Answer 9

Venous thromboembolism (VTE) is the process of blood clot formation in the veins. It includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

Question 10

What are the common clinical presentations of DVT?

Answer 10

Unilateral calf swelling, heat, pain, redness, and hardness. However, DVT can be asymptomatic or without any signs.

Question 11

What is the commonest site of DVT?

Answer 11

The leg, particularly the calf (popliteal and tibial veins) and the thigh (femoral and iliac veins).

Question 12

What are the differential diagnoses of DVT?

Answer 12

Baker’s cyst, cellulitis, muscular pain. A detailed history to determine any risk factors is key to differentiating DVT from other conditions.

Question 13

What is the investigation of choice for DVT?

Answer 13

Doppler ultrasound, which is quick, safe, and provides real-time 2D images. Colour Doppler (Duplex) can show the direction and velocity of blood flow, and thrombosed veins are non-compressible. A D-dimer test can be useful to rule out DVT if the probability is low. Contrast venography is rarely required, but can be useful in extensive disease or to look for anatomical malformations.

Question 14

How is DVT managed?

Answer 14

Treatment usually involves anticoagulation with heparin or low-molecular-weight heparin (LMWH), followed by warfarin or direct oral anticoagulants (DOACs). Compression stockings can be used to reduce swelling and prevent post-thrombotic syndrome. In severe cases or if anticoagulation is contraindicated, a filter can be inserted into the inferior vena cava to prevent pulmonary embolism.

Question 15

What is D-dimer and how is it used in the diagnosis of DVT/PE?

Answer 15

D-dimer is a breakdown product from fibrin, the fibrous mesh component of blood clots. It is only present when the coagulation system has been activated and is elevated in venous thromboembolism. A D-dimer test is very sensitive and can be used to rule out DVT/PE if low probability. However, it is not very specific, and a positive test is not diagnostic. In cases of high clinical probability, a D-dimer test should not be used.

Question 16

How is DVT treated?

Answer 16

The treatment of DVT depends on the location and extent of the clot. Symptomatic treatment is recommended for calf-only DVT, while ilio-femoral DVT requires anticoagulation with Direct Oral Anticoagulant (DOAC) such as Rivaroxaban or Dabigatran. The duration of treatment is usually 3-6 months for the first event and lifelong for the second event. In case of renal dysfunction, Warfarin may be used. Thrombophilia testing should be considered in individuals with a first-degree relative with VTE.

Question 17

What is CTPA and when is it used in the investigation of pulmonary embolism (PE)?

Answer 17

CTPA stands for CT pulmonary angiogram, which is a diagnostic imaging test that uses X-rays and contrast dye to create detailed images of the pulmonary arteries to detect any blockages or blood clots that could indicate a pulmonary embolism (PE). CTPA is only used if there is a reasonable likelihood of PE, and its use is guided by the Wells score, which takes into account various clinical features and risk factors for PE. In patients with a low probability of PE, a D-dimer test is usually done first, and CTPA is only done if the D-dimer test is positive.

Question 18

What is a ventilation-perfusion lung scan?

Answer 18

A ventilation-perfusion lung scan is a nuclear medicine test that uses inhaled and injected radioisotopes to identify a mismatch between lung ventilation and perfusion.

Question 19

What is the limitation of a ventilation-perfusion lung scan?

Answer 19

The limitation of a ventilation-perfusion lung scan is that it may not be useful in patients with underlying lung disease.

Question 20

In which situations is a ventilation-perfusion lung scan used when CTPA is contraindicated?

Answer 20

A ventilation-perfusion lung scan is used when CTPA is contraindicated due to severe contrast allergy, renal dysfunction, or high risk from radiation.

Question 21

What is the recommended treatment for a small PE?

Answer 21

A small PE can go straight to a DOAC (direct oral anticoagulant) treatment.

Question 22

What is the recommended treatment for a large PE?

Answer 22

Initially, a large PE should be treated with heparin, usually sc low molecular weight heparin (eg Enoxaparin). Then, the patient can be converted to either warfarin or DOAC (eg Rivaroxaban, Dabigatran) for 3-6 months for the 1st event. Lifelong anticoagulation is recommended for 2nd events or persistent risk factors such as thrombophilia.

Question 23

What should be considered when deciding on anticoagulation therapy for a patient with PE?

Answer 23

Co-morbidities, contra-indications, patient preferences, and bleeding risk can be assessed with a scoring system (e.g. HASBLED). Special circumstances such as renal function, extremes of body weight, cancer thrombosis, and APLS should also be considered.

Question 24

What is the treatment for massive PE?

Answer 24

The treatment for massive PE includes intravenous fluids, IV heparin infusion, and consideration of thrombolysis if the patient has shock +/- right heart strain. Other options include surgical embolectomy and catheter fragmentation.

Question 25

What are some preventative measures for VTE (venous thromboembolism)?

Answer 25

Prophylactic low dose sc heparin, low dose Rivaroxaban after major joint surgery, venous compression stockings, pneumatic compression stockings, early mobilisation, and good hydration.