Deep Vein Thrombosis ( DVT)

Acutely swollen leg

What is Deep Vein Thrombosis?

Simply the term “Thrombosis” means the blood clot formation inside a blood vessel in a living person. As the name suggest blood clot formation in deep veins of the body – mainly in the lower limbs is called  Deep Vein Thrombosis(DVT). 

This is not a condition usually present to surgical clinics. This is an acute condition, may be a life threatening condition if not treated properly. The common presentation is acute swelling and pain of the lower limb- calf. 

What are the similar presentations?

There are several other conditions that result in acute lower limb swelling. Those are 

  1. Cellulitis- inflammation of soft tissue of the limb
  2. Muscle or tendon rupture
  3. Ruptured Bakers cyst

In cellulitis the skin over the leg would be red in colour, warm to touch and painful. There may be signs of injury to the skin. 

The muscle rupture is a sudden event that may be a result during a forceful movement of the foot , most of the time during sports or exercise. 

Bakers cyst are common in adults with degenerative changes- osteoarthritis  of the joints. But there are children with Bakers cyst. Usually the Backers cyst located in back side of the knee joint and laterally. Rupture of the cyst can cause severe pain and swelling of the upper calf region. 

How people get Deep Vein Thrombosis?

There is a mechanism called “ Virchow’s triad” which describe three factors that contribute to formation of clots.  The factors are 

  1. Stasis of blood within the vessels
  2. Increase tendency of blood clotting ( Hypercoaguability)
  3. Damage to the inner layer of the vessel wall 

These three factors interact to produce blood clots. The factors that result in blood stains are blockade of a vessel, back flow due to incompetent valves in the veins( as in varicose veins). Hyper coagulability may be due to inborn disease conditions or acquired conditions such as some drugs or diseases. Invisible damage to vascular endothelium occurs due to hypertension , diabetes and some invasive procedures. 

When to suspect DVT?

As described above , the clinical features of DVT may mimic several other conditions. Therefore clinicians use a number of decision making tools to aid in patient management. The most commonly using one is the “ Wells score”.

Score Clinical Factor
1 pointActive cancer within 6 months or palliation
1 pointParalysis or plaster immobilisation of lower extremities
1 pointRecently bed ridden for more than 3 days or major surgery within 4 weeks
1 pointEntire leg swollen 
1 pointCalf swelling more than 3 cm , compared to the unaffected limb
1 pointPitting oedema
1 pointCollateral Superfical veins
1 pointPreviously documented DVT
-2 pointsAlternative Diagnosis more likely
Wells score- A decision making tools to aid in patient management in DVT.

More than 2 – high risk of DVT

Less than 2 low risk of DVT

Investigations in DVT?

When the the clinical features are suggestive of DVT a  venous duplex scan of the lower limb will be will confirm the diagnosis.

When scans is negative  a D-dimer test would be ordered.  If D dimer is negative DVT is unlikely, but if D-dimers are positive a repeat duplex scan in 2-3 days. Even with negative duplex, the clinical suspicious is high for DVT further investigation like Conventional Venography or newer imaging techniques like CT or MR- Venography  can be considered.

When clinical history is not highly suggestive a D-dimer test is ordered and if it is positive will proceed with duplex scan. If negative D-dimers , DVT is unlikely. 

How to Treat DVT?

When diagnosis is confirmed or highly suggestive clinical history awaiting scan, treatment can be started .

Immediate treatments should be started in deep vein thrombosis to prevent the lethal complication- Pulmonary embolism or to prevent the propagation of the thrombus. 

The treatment includes three aspects

  1. Oral anticoagulants
  2. Compression therapy 
  3. Mobilisation  

Treatment should be started as soon as the diagnosis has been confirmed or in a patient with a Wells score of 2 or more and/or a positive D-dimer test while await- ing duplex scan confirmation. 

The anticoagulation doesn’t resolve the clot but prevent the propagation of the clot. For the immediate action subcutaneous action of low molecular weight heparin is used and simultaneously oral anticoagulation with vitamin K antagonist( warfarin ) is started. When the target INR of 2-3 is achieved LMWH is omitted. For patient who had DVT for the fist time should be treated with oral anticoagulant at least for 3 months. But depending on the clinical condition of the patient, the physician would make the decision on continuing it further.

For the patient with recurrent deep vein thrombosis should be on lifelong anticoagulation. 

Compression therapy can be started wit short stretch bandage even when acute swelling presents. When acute swelling settles it can be changed to compression stockings. 

According to the available evidence early mobilisation is very effective.

Once a person develop DVT in his life, he has a 30% chance of getting Deep Vein Thrombosis(DVT) within next five years. 

Therefore in a ground of acutely swollen leg, attention should be payed on possibility of DVT. Quick diagnosis and immediate commencement of therapy would be prevent life threatening complication.

See our article on Varicose Veins also, click the link

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