Deep vein thrombosis (DVT) is a potentially lethal vascular condition that frequently develops deep within the muscular tissue of the legs without causing obvious external symptoms. Operating largely in secret, a blood clot forms in a major vein to block the vital return flow of blood to the heart, leaving patients unaware of the circulatory risk.
The primary danger of this hidden condition lies in its potential to transform into a life-threatening pulmonary embolism if a thrombus breaks free and travels to the lungs.
Recognising underlying risk factors, such as prolonged immobility or genetic predispositions, serves as a critical defence in unmasking this threat before it strikes.
According to Dr Paul Masinde, deep vein thrombosis (DVT) occurs when a blood clot develops in a vein deep in your body, often in your leg. This can happen because of a vein injury or slow-flowing blood. The blood clot, also known as a thrombus, may partially or completely block blood flow through your vein.
He further explains that someone who spends several days in bed because of illness, has recently undergone surgery, or has difficulty walking may be more vulnerable. Hospitalisation can also increase the risk because it often combines immobility with illness or surgery.
Major risks of deep vein thrombosis include pulmonary embolism, a potentially fatal condition where a blood clot breaks free and travels to the lungs, causing sudden shortness of breath, chest pain, or a rapid pulse.
Contributing factors include immobilisation from prolonged sitting, bed rest, or surgery, alongside health factors such as smoking, obesity, cancer, and genetics.
“Deep vein thrombosis is often silent because the human body utilises alternative routing channels to return blood to the heart, which masks early blockages. Furthermore, because deep veins carry deoxygenated blood rather than oxygen-rich arterial blood, restricted flow avoids triggering acute distress signals. This contributes to the asymptomatic nature of the condition, with research showing that approximately half of all individuals with DVT experience no symptoms,” explains Dr Masinde.
Common signs of DVT include swelling, pain or tenderness in one leg, warmth over the affected area and changes in the colour of the skin. The swelling may occur in the calf, ankle or entire leg. The pain can feel like cramping or soreness and may become more noticeable when standing or walking.
DVT is sometimes called a “silent” condition because some people have few or no symptoms. Yet when symptoms do appear, they can be easy to overlook or confuse with other conditions.
What makes DVT particularly difficult to recognise is that these symptoms are not always dramatic.
It occurs when blood flow slows, veins are damaged or the blood clots more easily. Risk factors include prolonged inactivity, surgery, injury, cancer, heart conditions, inherited clotting disorders, smoking, obesity, pregnancy and oestrogen-based contraception.
Symptoms alone cannot confirm DVT.
Doctors may use a D-dimer blood test and ultrasound to detect a clot.
Treatment typically involves blood thinners to prevent clots from growing or forming.
To reduce risk, stay active and avoid prolonged sitting.
On long journeys, walk regularly and move your feet and ankles.
After surgery or illness, follow medical advice on movement and prevention. Maintaining a healthy weight and avoiding smoking can also help.