Difference Between Thrombus and Embolus

Main Difference – Thrombus vs Embolus

The circulatory system is composed of blood vessels and the heart. Blood vessels (arteries and veins) facilitate the passage of blood throughout the body. Blood cells suspended in the plasma travel through blood vessels. Blood clots are solid masses that travels through the vessels along the blood. They are made up of either platelets, fibrin, fat, amniotic fluid, a tumor or air. Foreign substances such as iodine, cotton, talc or a piece of catheter tube can serve as blood clots. Thrombus and embolus are two terms used interchangeably to describe blood clots. The main difference between thrombus and embolus is that thrombus refers to a firm mass of blood clot developed within the circulatory system whereas embolus refers to a piece of thrombus that travels through the blood vessels. An embolus travels until it reaches the tiny blood vessels that are too small to pass through it.

Key Areas Covered

1. What is a Thrombus
– Definition, Facts, Symptoms
2. What is an Embolus
– Definition, Facts, Symptoms
3. What are the Similarities Between Thrombus and Embolus
– Outline of Common Features
4. What is the Difference Between Thrombus and Embolus
– Comparison of Key Differences

Key Terms: Blood Clot, Embolism, Embolus, Ischemia, Site of Origination, Thromboembolus, Thrombosis, Thrombus

What is Thrombus

Thrombus refers to a blood clot formed inside the circulatory system that can impend blood flow. Generally, it stays attached to the site of the blood vessel where it is formed. A blood clot can be formed as a result of injury to a blood vessel or tissue. Aggregation of platelets forms a quick plug to prevent bleeding. The formation of blood clots is induced by certain conditions such as high cholesterol, tobacco smoking, diabetes, cancer, being obese or overweight, stress, and sedentary lifestyle. A thrombus in a vein is shown in figure 1.

Figure 1: Venous Thrombus

A thrombus causes thrombosis. Depending on the location, several types of thrombosis can be identified: arterial thrombosis, venous thrombosis, and deep vein thrombosis (DVT). As both arterial and venous thrombosis prevent the blood flow, they may cause life-threatening complications in the patient. The symptoms occur when the thrombus restricts the blood flow through the lumen. The arterial thrombosis may cause unstable angina, peripheral arterial limb ischemia, ischemic stroke, and heart attack. The venous thrombosis may cause swelling, pain, and tenderness in the calf, red skin at the back of the leg, and aches and warm sensations in the skin.

What is an Embolus

Embolus refers to a blood clot, fatty deposit or air bubble carried by the bloodstream until it lodges in a blood vessel. It may travel either through arteries or veins. As embolus is a piece of blood clot detached from a thrombus, it is also called a thromboembolus. The lodging of the embolus occurs when the diameter of the blood vessel is too small for it to pass through. Since it blocks the blood flow, the tissue that receives blood from the vessel may starve of oxygen (ischemia) and eventually die. This clinical condition is called the embolism. Embolism is illustrated in figure 2.

Figure 2: Embolism

Several types of embolism can be observed depending on its location. They are pulmonary embolism, brain embolism, and retinal embolism. Pulmonary embolism is the blockage of an artery in the lungs by an embolus of DVT. Brain embolism may cause an ischemic stroke or transient ischemic attack (TIA) in the brain. Retinal embolism occurs by blocked arteries in the retina of the eye. The ischemic stroke is shown in figure 3.

Difference Between Thrombus and Embolus_Figure 3

Figure 3: Ischemic Stork

Some embolisms are caused by other particles rather than blood clots. They are septic embolism, amniotic embolism, air embolism, and fat embolism. Infectious particles cause septic embolism. Amniotic fluid in the womb can block the arteries in the mother’s lung. Causing amniotic embolism. Air embolism may occur in scuba divers while rising to the surface rapidly. Fat or bone marrow particles may cause fat embolism.

Similarities Between thrombus and Embolus

Both thrombus and embolus refer to blood clots.
Both thrombus and embolus occur inside the circulatory system.
Both thrombus and embolus are made up of platelets, fibrin, fat, amniotic fluid, a tumor, air or foreign substances.
Both thrombus and embolus can block the lumen of the blood vessels.

Definition

Thrombus: Thrombus refers to a blood clot formed inside the circulatory system that can impend blood flow.

Embolus: Embolus refers to a blood clot, fatty deposit or air bubble carried by the bloodstream until it lodges in a blood vessel.

Significance

Thrombus: Thrombus is a blood clot that develops inside the circulatory system.

Embolus: Embolus is a blood clot that travels through the blood vessels.

Size

Thrombus: Thrombus is large.

Embolus: Embolus is a piece of thrombus.

Source

Thrombus: Thrombus is always caused by blood constituents such as platelets, fibrin, and cellular elements.

Embolus: 99% of embolus are originated from thrombus. Others may occur due to air, infectious particles or fat.

Phase

Thrombus: Thrombus is a stationary mass.

Embolus: Embolus is a freely floating mass.

Obstruction

Thrombus: Thrombus obstructs the site of origination.

Embolus: Embolus obstructs a site that is distant from the site of origination.

Types

Thrombus: Arterial thrombosis, venous thrombosis, and DVT are the types of thrombosis.

Embolus: Pulmonary embolism, brain embolism, and retinal embolism are some of the several types of embolism.

Pathology

Thrombus: Thrombus impedes blood vessels, causing thrombosis.

Embolus: The lodging of an embolus in the blood vessels of the brain, heart or lungs can be fatal.

Symptoms

Thrombus: The impeding of blood vessels by a thrombus may cause pain, redness, swelling, warmth, unstable angina, peripheral arterial limb ischemia, ischemic stroke, and heart attack.

Embolus: The obstruction of a blood vessel by an embolus may cause cough, shortness of breath, excessive sweating, irregular heartbeat, and chest pain.

Treatment

Thrombus: Anticoagulants and compression socks are used to avoid thrombosis.

Embolus: Anticoagulants, painkillers, antiplatelet medications, thrombolytics, and surgery are used to avoid embolus.

Conclusion

Thrombus and embolus are two types of particles that can block the blood vessels in the circulation system. Most thrombus and embolus are blood clots. Thrombus is located in the site of origination while embolus can be a piece of thrombus that breaks off from a thrombus. Thrombus impedes the blood vessels at its site of origination. However, embolus blocks the blood vessels located away from the site of origination. Embolus causes severe clinical complications compared to thrombus. The main difference between thrombus and embolus is their role in the circulation.

Reference:

1.Ingleson, Kanna. “What is a thrombus? Causes and types.” Medical News Today, MediLexicon International, Available here.
2.“Embolism – Causes, Symptoms, Treatment, Diagnosis.” Causes, Symptoms, Treatment, Diagnosis – MedBroadcast.Com, Available here.

Image Courtesy:

1. “Blood clot diagram” By en:User:Persian Poet Gal (CC BY-SA 3.0) via Commons Wikimedia
2. “Blausen 0089 BloodClot Motion” By “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia
3. “Stroke ischemic” By National Heart Lung and Blood Insitute (NIH) – National Heart Lung and Blood Insitute (NIH), Public Domain) via Commons Wikimedia