Venous Thrombosis

Question 1

At which site(s) does DVT most commonly occur?

Answer 1

Pelvis and leg. Can occur in any vein.

Question 2

How does DVT typically present?

Answer 2

1. Often asymptomatic
2. Warmth
3. Swelling
4. Tenderness
5. Superficial venous distension

Question 3

What are the differentials for a warm and swollen leg with tenderness?

Answer 3

1. Ruptured Baker’s cyst
2. Oedema from other causes
3. Cellulitis

Question 4

How might the clinical probability of a DVT be estimated?

Answer 4

Wells score.

History (+1 for each)

• Lower limb trauma/surgery/immobilisation in plaster cast
• Bedridden for >3 days or surgery within last 4 weeks
• Malignancy (including treatment up to 6 months previously)

Clinical findings (+1 for each)

• Entire limb swollen
• Calf swelling >3 cm compared to asymptomatic side (measured at 10 cm below tibial tuberosity
• Pitting oedema (greater in symptomatic leg)
• Dilated collateral superficial veins (non-varicose)

Possible alternative Dx (-2)

• Musculoskeletal injury
• Haematoma
• Chronic oedema
• Cellulitis of leg
• Arthritis of leg
• Baker’s cyst

Total score
≤0: 3% (low risk)
1-2: 17% (moderate risk)
≥3: 75% (high risk)

Question 5

What is the main aim of therapy in DVT?

Answer 5

Prevent pulmonary embolism

Question 6

How is DVT managed?

Answer 6

1. Anticoagulation
   - Heparin then warfarin (continued for 3 months)
   - 4 weeks if significant risk factor, e.g. bed rest
2. Thrombolytic therapy
   - If large iliofemoral thrombosis
3. Elastic support stocking
   - For post-thrombotic syndrome

Question 7

What are the main complications of DVT?

Answer 7

1. PE
2. Post-thrombotic syndrome (from destruction of deep-vein valves)
   - Persistant pain
   - Swelling
   - Oedema
   - Venous eczema
   - Ulceration
3. Recurrence of thrombosis

Question 8

What is main complication of chronic venous obstruction?

Answer 8

Post-phlebitic syndrome

• Persistant pain
• Swelling
• Oedema
• Venous eczema
• Ulceration

Question 9

Name 2 drugs implicated in the prevention and treatment of thromboembolism

Answer 9

1. Heparin
2. Warfarin or NOAC
   Start simultaneously.

Question 10

Which drugs might be considered as an alternative to warfarin? Describe the pros and cons

Answer 10

Novel oral anticoagulants (NOACs) - e.g. apixaban, dabigatran, riveroxaban

• Direct thrombin inhibitors
• Used in VTE, AF and MI
• Rapid onset of action
• Administered in fixed dose without need for monitoring
• Fewer drug interactions
• But elimination primarily renal
• Abnormalities of liver function

Question 11

How many people die from preventable hospital-acquired VTE each year?

Answer 11

About 25,000

Question 12

Name 3 prophylactic measures against hospital-acquired VTE

Answer 12

1. Early mobilisation
2. Leg elevation
3. Compression stockings
4. Thromboprophylaxis with LMWH

Question 13

In which patients is thromboprophylaxis with LMWH indicated?

Answer 13

1. Medical inpatients with any risk factor
2. Patients undergoing minor surgery (anaesthetic 60 mins) without risk factors (20 mg)
3. Patients undergoing major surgery (anaesthetic >60 mins) and with risk factors (40 mg)

Question 14

What should you obtain before starting treatment of an established thromboembolism?

Answer 14

1. Coagulation screen
2. Platelet count
   To exclude pre-existing thrombotic tendency.

Obtain objective evidence of thrombosis asap - though heparin is often started on basis of clinical suspicion .

Question 15

True or false: you must obtain objective evidence of thrombosis before starting anticoagulation

Answer 15

False - heparin is often started on basis of clinical suspicion; obtain evidence asap

Question 16

True or false: patient requiring LMWH can be safely treated as outpatients

Answer 16

True - where feasible in selected patients

Question 17

Describe the anticoagulation regime for treating VTE

Answer 17

• Warfarin and heparin started at same time
• Overlap for minimum of 5 days
• Heparin continued until INR is in therapeutic range (INR: 2-3)
• Measure platelet count if receiving heparin >5 days
• Anticoagulation (warfarin) continued for 6 weeks after 1st thrombosis with precipitating cause (provided no risk factors)
• Long-term anticoagulation if repeated episodes or continuing risk factors

Question 18

What are the major side-effects of heparin therapy?

Answer 18

1. Bleeding
2. Thrombocytopenia
   Measure platelet count in all patients receiving heparin for >5 days.

Question 19

List the indications for oral anticoagulation and their target INRs (11 in total)

Answer 19

Dose adjusted to maintain INR, usually 2-3 times control value.

Target INR

2. 5: PE, DVT, thrombophilia, AF, cardioversion, mural thrombus, cardiomyopahty
3. 5: Reccurrence of VTE while of warfarin therapy, antiphospholipid syndrome, prosthetic heart valve, coronary artery graft thrombosis

Question 20

What are the risk factors for venous thromboembolism in hospital inpatients? (16 in total)

Answer 20

1. Age >60
2. One or more significant medical comorbidities (e.g. heart disease, respiratory failure, acute infection)
3. Obesity (BMI >30 kg/m2)
4. Major abdominal/pelvic surgery
5. Active cancer or cancer treatment
6. Pregnancy
7. Use of oestrogen-containing OCP/HRT
8. Significant immobility
9. Varicose veins with phlebitis
10. Diabetic coma
11. Personal or 1st degree relative history of VTE
12. Thrombophilia
13. Inflammatory bowel disease
14. Nephrotic syndrome
15. Critical care admission
16. Dehydration