What is the difference between embolism and thrombosis?

The embolism and the thrombosis are conditions of the circulatory system that cause reduced or blocked blood flowso their definition, symptoms and consequences often overlap and make them confusing terms even for health professionals.

Next we will see what exactly embolism and thrombosis consist of and how they differ.


The thrombosis is the reduction of blood flow by the formation of a clot inside a blood vessel. The thrombus it grows attached to vascular wall and as it grows, it reduces the flow of blood through the vessel.

The reduction in blood flow occurs at the site of thrombus formation.

The clot that produces thrombosis can be formed for very different reasons, but the atherosclerosis is the most frequent.

Other causes are increased blood clotting associated with various diseases and blood vessel disorders that trigger the coagulation cascade, for example breaks and fissures in the vascular wall.

Thrombosis in a venous valve
Thrombosis in a venous valve


The embolismmeanwhile, is the blockage of blood flow by any body, called plungerthat it moves until it finds a small caliber vessel and plugs it.

obstruction does not occur on site as in thrombosis, but from distance. The embolus travels through the bloodstream until it finds a vessel that it cannot pass through.

Emboli can be of a diverse nature, including clots that break off from a thrombosis. That is, thrombosis reduces the flow of blood in a vessel, and if a fragment breaks off, it forms an embolus that can cause an embolism.

Embolisms can have their causes in other types of materials, not just blood clotsfor example in fat globules, air or gas bubbles and any other type of foreign body that enters the bloodstream.

The blocked blood vessel may be a healthy vessel, unlike thrombosis that develops in damaged blood vessels.

thrombus embolism
Embolism due to loosening of a clot

Main differences

As mentioned, the key differences between an embolism and a thrombosis are:

  • The thrombosis is produced by a blood clot attached to the altered vascular wall. The embolism for plungerwhich may be a clot or other material.
  • The thrombosis it is produced on-sitethe embolism it is produced from distance (the plunger travels through the bloodstream until it is clogged).
  • The thrombosis affects a altered blood vesselthe embolism can be given in a glass healthy blood.
  • Both reduce or block blood flow and can cause similar symptoms.

common symptoms

Embolism and thrombosis share many symptoms and the health risk depends fundamentally on the blood vessels that are affected, their location and the degree of blood flow blockage, being the deep veins of the lower extremities, large arteries, cerebral arteries, pulmonary blood vessels and coronary arteries that present a greater risk to the patient's life.

Small thrombi and embolisms do not usually block the passage of blood significantly, to the point that approximately 50% of cases of deep vein thrombosis, one of the most dangerous, do not develop symptoms. But larger blockages can deprive healthy tissue of nutrients and oxygen, causing it to inflammation and eventually tissue death by necrosis.

Venous and arterial thrombosis

Veins are the blood vessels responsible for carrying blood back to the heart for recirculation. When a main vein sees its flow reduced by thrombosis, the blood behind the obstruction accumulates and suffers extravasation, producing edema, swelling and inflammation.

Although venous thrombosis can occur anywhere, deep vein thrombosis in the lower extremities are the most common. Thrombosis in superficial veins or in small veins does not usually generate major complications.

On the other hand, the arteries are the blood vessels that carry blood from the heart to the different organs and tissues. Arterial thrombosis and embolism are frequently associated with atherosclerotic plaques that grow, reducing the lumen of the vessel and increasing the pressure on the vascular wall. If the pressure becomes enough, it can rupture the plate and become unstable.

In this situation, the immune system overreacts and begins the formation of a large clot that hinders blood flow and can become life-threatening by causing heart attacks and strokes. Symptoms of arterial thrombosis that warn of this emergency situation usually include chest pain that does not go away with medication and that can appear suddenly, shortness of breath, sweating, nausea, loss of muscle strength and facial paralysis on one side.

pulmonary embolism

Pulmonary embolism occurs when an embolus blocks blood flow to the lungs and is often associated with deep vein thrombosis. A fragment of the clot formed in the veins breaks off and travels through the bloodstream, passing through the heart, until it reaches the pulmonary arteries.

Pulmonary embolism can be very dangerous and develop very fastSudden death is the first symptom detected in approximately 25% of pulmonary embolisms. The most common warning signs of a pulmonary embolism include shortness of breath, rapid breathing, increased heart rate, dizziness and lightheadedness, chest pain that worsens when inhaling, and coughing up blood.

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