Thromboembolism refers to a condition where a blood clot formed in the blood vessel unplugs itself and flows in the blood stream to block another blood vessel leading to obstruction of blood flow. Although clotting is a normal bodily function, if a clot occurs where it is not required, it may lead to serious problems.

Types of Thromboembolism:

The type of thromboembolism differs depending on the area in which the clot may appear. It can obstruct the blood flow in the veins, arteries, brain, gastrointestinal tract or kidneys.

Thromboembolism can be further classified as below:

Venous Thromboembolism:

A venous thromboembolism is a thrombus (blood clot) formed in a vein. The blood flow in the veins is slow when compared to arteries which can increase the likelihood of the blood clots forming in these vessels.

It can be categorized into three different types

• Superficial Vein Thrombosis
  The clot may occur in a superficial vein, close to the surface of the body. Usually, it is not serious until it enters the deep veins.

• Deep Vein Thrombosis (DVT)
  Deep vein thrombosis occurs within the deep veins, and mostly occurs within the legs.
  
• Pulmonary embolism (PE)
  Pulmonary embolism is a medical emergency in which the thrombus blocks the blood vessel in the lungs.

Renal Vein Thrombosis (RVT)

A renal vein thrombosis is a thrombosis that occurs in the veins that drain blood away from the kidneys. These clots reduce the ability of the kidneys to clean and filter the blood.

Arterial Thrombosis (atherothrombosis)

Arterial thrombosis is much less common than venous thrombosis. It can have similar risks. Usually arterial thrombosis may lead to necrosis of the tissue.

A thromboembolism in the coronary artery can cause a heart attack. If blood supply to the brain is disrupted, the patient may suffer a stroke.

Symptoms:

Signs and symptoms of venous thromboembolism include the following

DVT

• Pain in arm or leg, usually in the thigh or calf
• Swollen leg or arm
• Reddening or warming of the skin
• Red streaks on the skin

PE

• Shortness of breath
• Chest pain under your rib cage that can get worse when you take a deep breath
• Rapid heart rate
• Feeling lightheaded or passing out
• Accentuated second heart sound

Arterial Thrombosis

• Muscle pain or spasm in the affected area
• Numbness and tingling in the arm or leg
• Pale color of the arm or leg (pallor)
• Weakness of an arm or leg

If the condition is severe, it may lead to blister formation and shedding of the skin, leading to tissue necrosis.

Symptoms of a clot in an organ vary with the organ involved but may include:

• Pain in the part of the body that is involved
• Temporary decrease in organ function

Causes:

The blood clots can occur due to injury to a vein, consequence of a surgery, use of certain medications and lack of movement of the limbs.

In the case of PE, the blood clot may block the blood vessels of the lungs. The affected portion of the lung may die due to loss of blood supply, the condition is called as pulmonary infraction, making it difficult to provide oxygen to the rest of the body.

Occasionally, the blood vessels can be blocked by substances other than blood like collagen, part of a tumour, air bubbles etc.

Risk factors:

The common risk factors include

• Inheriting a blood-clotting disorder
• Prolonged immobility which may be due to bed rest or long trips
• Injury or surgery
• Pregnancy
• Birth control pills or hormone replacement therapy
• Being overweight or obese
• Smoking
• Cancer
• Heart failure
• Inflammatory bowel disease
• Family history of deep vein thrombosis or pulmonary embolism

Diagnosis:

The diagnosis of thromboembolism includes the following tests which could be considered depending on the type:

D-dimer: The blood sample is tested for the presence of D-dimer which is a marker for the presence of blood clots.

Duplex Ultrasound: This is an imaging test in which the presence of clots is identified using ultrasound waves.

Pulse oximetry: In this test, a sensor attached on the end of the finger of the patient helps to measure the level of oxygen in the blood.

Arterial blood gas: The blood drawn from the artery is checked for oxygen levels present in it.

Chest X-ray: This test may not be useful in finding the presence of clots, but can help to rule out a clot.

Other diagnostic tests may include ELISA, pulmonary angiography, venography, echocardiography, helical computed tomography of pulmonary vessels etc.

Treatment:

Treatment of thromboembolism includes:

Blood thinners: These are anticoagulant drugs which prevent formation of new clots while the body works to break up the previous clots present. They include heparin, low-molecular-weight heparin, apixaban, edoxaban, rivaroxaban, and warfarin.

Clot-busting drugs: These are intravenous injections to dissolve the clots in the case of life-threatening situations. They include drugs belonging to the class of tissue plasminogen activators.

Surgical and other procedures:

• Removal of clot: Surgery is considered only if the condition is life threatening. The clot is removed using a catheter threaded through the blood vessel.
• Vein filter: A catheter can also be used to position a filter in the inferior vena cava which helps to stop the clots from being carried into the lungs.

Prevention:

If the patient is at a risk of the condition, the following preventive measures may be considered to reduce the occurrence:

• Use of blood thinners
• Use of compression stockings
• Use of intermittent pneumatic compression devices that automatically squeeze the legs to keep blood flowing

Other preventive measures include

• Regular exercise
• Maintaining healthy weight
• Cessation of smoking

Consideration during travel include

• Walk every 1 to 2 hours
• Stretch legs and move around on the seat
• Drink lots of fluids
• Avoid smoking and consumption of alcohol before journey