Deep Vein Thrombosis (DVT)

Deep vein thrombosis can have acute or short-term issues and long term issues. Therefore based on the time presentation, DVT can be acute DVT (a-DVT) or chronic (long term DVT). Acute DVT is one that has occurred in the acute setting, where the clot has been formed in the first 14 days. Clots formed between 14 days to 1 month are called subacute DVT. Long standing (>1 month) remnant clots are called choric/long standing DVT.

Acute Deep Vein Thrombosis: Thrombus formed within the first month is called acute DVT. Acute DVT can cause acute sudden symptoms like redness, tenderness, swelling and pain in the leg. Sometimes, the swelling is so severe that the leg can become pale or blue due to blood pooling and blood stagnation. Rarely, an even worse symptom is compartment syndrome where the swelling is so severe that even arterial blood cannot reach the leg, this is a medical emergency.

The blood clots also have the ability to break free and travel through your bloodstream till your heart – this condition is called pulmonary thromboembolism (PTE/PE). Pulmonary embolism (PE) happens when the blood clots travel and get stuck in the blood vessels of your lung. Large clots may cause difficulty in breathing, drop of blood pressure or saturation. A quick diagnosis and treatment is needed, as this can be a life-threatening condition.

Chronic Deep Vein Thrombosis: Patient who have had DVT in the past (>1 month), which may or may not have been treated is called chronic DVT. About 50% of people who have DVT in their legs, will experience long term complications of DVT. Symptoms of chronic DVT may include cramping leg pain, swelling, pigmentation and recurrent ulcers affecting the quality of life. This is known as post-thrombotic syndrome (PTS) and may occur as a result of damage to the vein's inner lining and valves, which causes blood to accumulate more than it is supposed to. The affected leg is always hard, swollen and may show skin pigmentation and discolouration.

DVT occurs whenever blood gets stagnated in the legs for a long time, thus increasing the risk of thrombosis. DVT occurs based on something called the Virchow Triad i.e the blood is stagnant, hypercoagulable and there may be associated vessel wall injury. This predisposes to clotting following a triggering factor.

The following may contribute to increasing the risk of having deep vein thrombosis:

1. Family history of DVT

2. Prolonged immobilisation

3. Facing cancer and its chemotherapy treatment

4. Recent Injury/trauma

5. Recent surgery, or immobility restrict the blood flow in a deep vein

6. Pregnancy

7. Smoking & Tobacco use

8. History of varicose veins

9. Extreme dehydration

10. History of long travel causing standing or sitting in one place for a long time

• The doctor would undertake a physical examination and look over the medical records.
• A detailed history will be taken. Imaging tests would be advised.
• Symptoms generally involve sudden onset pain and swelling.
• The first test to determine DVT is usually a duplex venous ultrasound, since it is safe, easily accessible and non-invasive.
• Ultrasound waves are used in this test to display blood clots and blood flow in the veins. Doctor may choose to use another imaging test (like an MR Venography) if the Doppler test is unclear (especially in fatty and obese patients).
• Magnetic Resonance Imaging (MRI) presents a non-invasive test to see of organs and structures inside the body. An MRI shows pictures of the veins in their exact locations in the body.
• An MR Venography may be advised to look for the extent of DVT or if the doppler results are not clear.
• CT Venography may be advised if a mass/tumour is suspected causing compression of the veins. CT may also be advised to look for pulmonary embolism.

What is the role of haematological testing in DVT

There are special tests requested to know if the patient have an underlying genetic condition predisposing to DVT. These tests include a panel of investigations to look for factor deficiencies in the blood. They cannot be done when the patient is on blood thinners since the results may be askew. Therefore, they are best done either before initiation or after 6-9 months, when anticoagulation can be stopped for a few days if the clot gets stable.

Haematological testing is advisable in the following clinical conditions:

• Young patients
• Recurrent DVT
• Unprovoked DVT
• Family history of DVT
• Venous thrombosis in other parts of the body
• Concomitant arterial and venous thrombosis

What is provoked versus unprovoked DVT?

Provoked DVT is when there is an underlying triggering factor that causes DVT for example history of prolonged immobilisation, dehydration or recent surgery. Unprovoked DVT is when there is no external triggering factor which has caused DVT. Unprovoked DVT is most likely due to an underlying genetic condition which causes the blood to be hypercoagulable.

Any other tests required for DVT management in the acute setting?

Routine blood tests will be ordered. A 2D echo will be asked for to look for pulmonary thromboembolism. If suspected, then a pulmonary angiography may be asked for. Creatinine levels may be requested, since these will be deranged. An ultrasound abdomen may be requested to look for a mass compressing the veins and causing DVT.

Chronic DVT is managed with compression stocking only. Acute DVT generally requires admission for monitoring. Patients need to be started on blood thinners or anticoagulants. Anticoagulants (blood thinners) make it harder for your blood to clot also stop clots from getting bigger and prevent blood clots from moving. The body has the ability to clear blood clots naturally but in some cases it doesn’t clear it totally.

Many types of anticoagulants are available in market like warfarin, heparin,etc. The doctor will suggest you the best possible medication for you. Oral form of anticoagulants like rivaroxaban and apixaban are now available. They need to be continued for upto 6-9 months. DVT treatment varies with each individual like if you had clots earlier, are you getting treatment for cancer and so on. The most common side effect of anticoagulants is bleeding. It is advised you connect with your doctor if you observe any injury or bleeding to avoid serious damages.

Recently newer treatment options like pharmacomechanical thrombectomy is available for acute DVT. This involves removing the entire clot from your veins using special devices and catheters. This should especially be promoted in young patients with acute/hyper-acute extensive DVT to prevent long term complications like post thrombotic syndrome. The exact details about the procedure, the management protocol is variable from case to case.