CE is mainly caused due to irregular heartbeats called atrial fibrillation. In this condition, the atria beat rapidly instead of slowly . Hence, blood within the atria does not empty out completely into the ventricles. The blood that stays back stagnates and forms a blood clot that enters the blood circulation process leading to death.

This is a condition when a clot moves from the legs to the lungs. The clot blocks the lung artery stopping blood flow and oxygen to the lung tissue. This causes pulmonary hypertension and damage to other organs too, as oxygen does not reach them. Eventually PE leads to sudden death.

When a patient is confined to bed for long, there isn’t much movement in the body. Blood starts flowing slowly through the veins. This could cause clots due to stagnation of blood.

Patients, who have undergone surgeries in the leg, hip or the pelvis, are at risk of getting blood clots in their blood vessels. This is because the walls of the blood vessels get damaged during surgery.

Cancer patients are also at a risk of having blood clots in the veins. The blood clots are a result of the damage to the veins due to chemotherapy and other treatments they undergo.

Haemophilia A is the most common genetic disorder which weakens the body’s ability to clot blood.It is usually found in males rather than females. One in 5,000–10,000 males suffer from Haemophilia A . Haemophilia B is also a deficiency that occurs in one out of 20,000–34,000 males.

Injections given directly to the veins can, at times, cause irritation or inflammation of a vein. When the vein is punctured, there is increased blood flow in that area and a blood clot can form. Thrombophlebitis is the uncomfortable outcome of taking intravenous medication, but the condition is rarely a risk to life. Thrombophlebitis can also be the outcome of bacterial infection caused by a bacteria named Staphylococcus.

Smoking, oral contraceptives, lack of exercise, high intake of oestrogens, deskbound work and obesity support deep vein thrombosis (DVT). These blood clots, formed in the vein, can travel into the blood stream and lodge in the lungs blocking blood flow.

Arterial walls thicken slowly and harden making an artery narrower with time. Blood flow reduces, making the artery weak and susceptible to injury. Any tear in the artery can lead to the formation of a blood clot that blocks the contracted artery completely, disallowing blood or oxygen to reach the heart or the brain.