DVT

Question 1

Define DVT

Answer 1

Formation of a thrombus within the deep veins (most commonly in the calf).

Question 2

Explain the aetiology/risk factors of DVT

Answer 2

• Deep veins in the legs are more prone to blood stasis, hence clots are more likely to form -> Virchow’s triad

• Risk Factors
○ COCP - combined oral contraceptive pill
○ Major surgery within last 3 months
○ Polycythaemia
○ Thrombophilia (e.g. protein C deficiency)
 - Protein S deficiency
 - Factor V leiden
 - Hospitalisation within last 2 months
 - Trauma; inc of lower limbs
○ Prolonged immobility
○ Pregnancy
○ Dehydration
○ Active cancer - precipitated by taking certain drugs

Weaker rfs;
○ Obesity
○ Smoking - usually in conjuction with taking cocps etc
- Recent long haul flight

Question 3

What is virchows triad?

Answer 3

1. Stasis
2. Hypercoagulable state
3. Blood vessel injury

Question 4

Summarise the epidemiology of DVT

Answer 4

• VERY COMMON

* Especially in hospitalised patients

Question 5

Recognise the presenting symptoms of DVT

Answer 5

• Swollen calf/ limb
• Painful (but can be painless) - can be localised to path of deep veins

Signs;
Redness
Warmth

Question 6

Recognise the signs of DVT on physical examination

Answer 6

• Examination of the Leg

○ Local erythema, warmth and swelling
○ Measure the leg circumference
○ Prominent superficial veins - not varicose
○ Skin colour changes - can become blue if leads to ischaemia
- Assymetrical oedema

○ NOTE: Homan’s Sign - forced passive dorsiflexion of the ankle causes deep calf pain

Question 7

What scoring system is used to stratify risk in DVTs?

-Name risk factors scored with the system

Answer 7

Risk is stratified using the WELLS CRITERIA (NOTE: this is different from the Pulmonary Embolism Wells criteria)

○ Score 2 or more = high risk.
Yes = +1 No = 0

Active cancer
Treatment or palliation within 6 months

Bedridden recently >3 days or major surgery within four weeks

Calf swelling >3 cm compared to the other leg
Measured 10cm below tibial tuberosity

Collateral (nonvaricose) superficial veins present

Entire leg swollen

Localized tenderness along the deep venous system

Pitting edema, confined to symptomatic leg

Paralysis, paresis, or recent plaster immobilization of the lower extremity

Previously documented DVT

Alternative diagnosis to DVT as likely or more likely (-2)

Question 8

How does one examine for Pulmonary embolism apart from the leg?

Answer 8

○ Check respiratory rate, pulse oximetry and pulse rate

they will be; tachypneoic (fast RR), tacchycardic, low o2 sats

Question 9

Identify appropriate investigations for DVT

Answer 9

1. Before any of these, risk stratify using Well’s score to guide preceding treatment.
2. Doppler Ultrasound - GOLD STANDARD
   
   • Aka Venous Duplex ultrasound
   • 1st line test with high Wells score or..
   • ..low score with elevated d-dimer
   • Assesses venous flow.
   • High sensitivity and specificity
   • Can do a proximal ultrasound or whole leg.
3. Bloods; Quantitative D-dimer
   - Do first if Wells score below 2 (so if DVT technically unlikely)
   - If normal exclude DVT. If high, do ultrasound.

test INR before starting warfarin and aptt before heparin
• If PE suspected
○ ECG
○ CXR
○ ABG

Question 10

Generate a management plan for DVT in a patient with no active bleeding or Pulmonary embolism related cardiovascular compromise.

Answer 10

1. Anticoagulation - 1st line
2. Physicl activity
3. Gradient Stocking

Anticoagulation;

• Many drugs ending with ‘an’ i.e. rivaroxaban, apixaban, dabigatran, can be given alone or;
• Warfarin. Waiting for warfarin to increase INR to the target range of 2- 3

○ DVTs that do NOT extend above the knee may be observed and anticoagulated for 3 months!!!
○ DVTs extending beyond the knee require anticoagulation for 6 months
○ Recurrent DVTs require long-term warfarin

CANNOT give warfarin in; Pregnancy, Cancer!!!

Question 11

What is INR?
What is the Interpretation of INR?

When is INR test indicated?

Answer 11

INR stands for International Normalised Ratio, aka Prothrombin time it is a standardised measurement of the time it takes for blood to clot.

A result of 1.0, up to 1.5 is normal.

A low INR result means your blood coagulates too easily and puts you at risk of developing a blood clot.

A high INR result means your blood coagulates too slowly and you risk bleeding. thin blood.

Indication;
1. before warfarin therapy
2. DVT
3. PE
4. AF
5. HF 
to check risk of clots

Question 12

Generate a management plan for DVT in a patient with active bleeding.

Answer 12

• IVC Filter
○ May be used if anticoagulation is contraindicated and there is a risk of embolisation

Retrievable inferior vena cava (IVC) filters are preferable to older models. Presence of an IVC filter is associated with a doubling of the long-term risk of recurrent lower-extremity DVT, owing to both the presence of thrombosis and the mechanical effects of the filter. Once bleeding has resolved, the patient may be assessed for initiation of anticoagulation and removal of the IVC filter.

• Prevention;
○ Gradient compression stockings
○ Physical activity
○ Prophylactic heparin (if high risk e.g. hospitalised patients)

Question 13

Identify 4 possible complications of DVT

Answer 13

1• PE
2• phlegmasia cerulea dolens - blue painful swollen leg due to thrombus causing ischaemia
3• Thrombophlebitis - inflammed vein (results from recurrent DVT)
4• Chronic venous insufficiency

Question 14

Summarise the prognosis for patients with DVT

Answer 14

• Depends on extent of DVT
• Below-knee DVTs have a GOOD prognosis
• Proximal DVTs have a greater risk of embolisation