7. Disease
Deep vein thrombosis

Deep vein thrombosis

A. Presentation

Cannot be diagnosed reliably on clinical grounds.

Often asymptomatic.

The leg may be warm and swollen, with calf tenderness and superficial venous distension.



B. Investigation

Blood test


Compression ultrasound

Bilateral compression ultrasound of the common femoral, popliteal and distal popliteal veins

If clinical suspicion is high, but scan result is negative, do venography.


Doppler ultrasound

May miss calf-vein thrombosis. Thus in the presence of high clinical suspicion, a negative result means the test should be repeated in 7 days to detect patients with proximal extension.


Impendance plethysmography

Less sensitive than ultrasound


Venography is the gold standard, but carries almost 5% risk of inducing DVT.


C. Treatment

Before anticoagulation therapy is started, blood should be collected for:


Give pain relieft if necessary


Low molecular weight heparin (must)

LMWH (e.g. enoxaparin, dalteparin) is at least as effective and as safe as an IV unfractionated heparin in the initial management of DVT. LMWH does not require laboratory monitoring and thus is the drug of choice.

LMWH should be given for a minimum of 5 days AND until the INR has been >2 for 24-48 hours.


Warfarin (must)

- Oral anticoagulation (warfarin) may be commenced on the same day as LMWH.

- INR should be monitored daily and dose adjusted according to INR until a therapeutic level is achieved.

- Warfarin should not be commenced alone, i.e. without LMWH, as this is associated with a high rate of subsequent DVT recurrence.

- Warfarin should be continued for at least 3 months after the first episode of DVT, and longer after the second episode of DVT. Indefinitely for idiopathic cases and recurrent venous thromboembolism.


Catheter-directed thrmobolysis (optional)

May reduce the risk of post-thrombotic syndrome but carries a risk of major bleeding of 10%.


D. Other notes

DVT occurs most commonly in the lower limbs




Post-thrombotic syndrome

Occurs most commonly after iliofemoral DVT.

Characterised by pain, swelling, venous hypertension changes (e.g. leg ulceration)


Clinical predicition rule to rank DVT risk

Ask about:

Look for:

Add up the points.

<0: low risk

1-2: moderate risk

>3: high risk


Risk stratification of DVT risk for hospitalised patients

High (40% to 80%)




Moderate (10% to 40%)




Low (<10%)





Pharmacological and non-pharmacological methods of prophylaxis are effective and their use in combination is additive.


Pharmacological prophylaxis

Unfractionated heparin (UFH) is the appropriate pharmacological methods in most cases.


Low molecular weight heparin is superior to UFH in preventing DVT in patients undergoing orthopaedic surgery, but has greater risk of epidural haematoma in patients undergoing epidural anaethesia.


Non-pharmacological prophylaxis

Graduated compression stocking

Sequential pneumatic compression device

Pneumatic foot compression device


Other measures

Adequate hydration

Early mobilisation

Leg elevation






Table of contents  | Bibliography  | Index