When a “thrombus” or a blood clot develops in one of the blood vessels, it reduces the blood flow and leads to a condition known as “thrombosis.” When a clot forms in the veins, it is known as venous thromboembolism and can result in deep vein thrombosis and pulmonary embolism. When it forms in the arteries, it is known as atherothrombosis and can result in heart attacks and strokes.

1. Causes of deep vein thrombosis (DVT)
Causes of DVT vary from patient to patient, but common contributing factors include the following:

• Stasis or alterations in normal blood flow caused by prolonged immobility, extended surgery, varicose veins.
• Injury to blood vessel
• Personal and family history
• Genetic mutation of blood clotting Factor V
• Side effect of chemotherapy, radiation, or heart/lung disease treatments
• Pregnancy
• Recent surgery, especially orthopedic or total knee replacement surgery
• Overweight/Obesity
• Old age
• Sedentary occupation, long flights, long road trips
• Extended bed-rest
• Certain health conditions like irritable bowel disease, Crohn’s disease, cancer, heart disease
• Genetic blood disorders and inherited conditions
• Smoking
• Contraceptives and hormone replacement therapy

Awareness of these causes of deep vein thrombosis and risk factors can increase awareness of the condition, help in early diagnosis and treatment.

2. Symptoms of deep vein thrombosis
Clots that form in a vein located deep inside the body (as opposed to surface veins), usually in the legs, can result in deep vein thrombosis. It prevents the blood from flowing freely through the vein, causing swelling, discomfort, pain, and discoloration of the area. Typical symptoms include:

• swelling without warning, trauma, or apparent cause in the legs, ankles, feet
• surface changes in the skin such as discoloration (red/blue tinge), ulceration, or thickening
• a feeling of heaviness, discomfort, itching, warmth, pain, tenderness
• distension of surface veins

In about 50% of cases, there are no symptoms, making this an extremely challenging condition to diagnose. The main complication is pulmonary embolism often referred to as a “silent killer.” If not identified in time, the blood clot can break free and travel to blood vessels in the lungs and this can result in fatal consequences. Post-phlebitic syndrome damages the blood vessels and results in pain, swelling, ulceration and skin discoloration.

3. Diagnosis of deep vein thrombosis
Physical exam and medical history provide valuable information to doctors. However, the symptoms alone may not be adequate to give a clear diagnosis of deep vein thrombosis. Doctors recommend further tests if they suspect the presence of the condition.

• A special blood test known as the D-Dimer test can help in diagnosis. It identifies loose fragments of clots floating in the bloodstream, indicating the presence of larger clots elsewhere in the blood vessels.
• However, this is not a completely reliable test and is used in conjunction with others like an ultrasound scan (Doppler) which can detect speed and ease of flow of blood through the vessels.
• Venograms are used when both these tests prove inconclusive. A contrast dye is injected into the vein and tracked by X-ray, which highlights the gaps in the blood vessels where clots have formed.