Difference Between Haemostasis and Thrombosis

Main Difference – Haemostasis vs Thrombosis

Haemostasis and Thrombosis, which are related to coagulation of blood within the blood vessels, are often confused by many people due to the thin line of demarcation which distinguishes one from the other. Both these terms are like two sides of the same coin and equally important for the effective functioning of the body in numerous ways. The main difference between Haemostasis and Thrombosis is that thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system whereas haemostasis is a natural clotting mechanism which takes place to prevent excessive bleeding following an injury.

This article explains,

1. What is Haemostasis? – Definition, Pathophysiology, Complications

2. What is Thrombosis? – Definition, Types, Pathophysiology, Complications

3. Difference Between Haemostasis and ThrombosisDifference Between Haemostasis and Thrombosis - Comparison Summary

What is Haemostasis

Haemostasis is defined as the normal physiological response which prevents the body from experiencing a significant blood loss following a vascular injury.

The fundamental mechanism of haemostasis is based on an intricate series of events which consists of the actions of platelets, other blood cells like tissue factor [TF]-bearing cells and specific blood proteins called coagulation factors.

On the very moment a vascular injury occurs following trauma, the triggered physiological haemostasis comes into action and begins a series of processes discussed below.

Just after the injury, the blood vessels will start constricting in order to reduce the blood flow to the affected area. Then, the circulating platelets will rush to the trauma site and get adhered to the vessel wall or endothelium,and  aggregate in clumps. Their activation which will initiate an intricate series of enzymatic reaction, resulting in coagulation. Furthermore, at the end of this cascade of actions, a protein known as Fibrin is produced to form a stable hemostatic plug which will halt further bleeding.

Haemostasis, in general, is a finely balanced process, carried out with the involvement of platelet and coagulant factors. However, if this balance gets disrupted due to any reason, it can give rise to increased morbidity and mortality, which might end up in death.

Main Difference - Haemostasis vs Thrombosis

What is Thrombosis

Thrombosis is defined as a process involving the formation of a blood clot or thrombus inside a blood vessel. Even though the fundamental process of this is quite similar to haemostasis, the degree or intensity is comparatively higher, and this usually occurs due to an underlying health condition.

The clot formed this way can obstruct the blood flow to the affected site and can lead to serious complications if it moves to vessels which supply blood to the important organs in the body such as brain or lungs.

Thrombosis can be classified into two main types known as venous thrombosis and arterial thrombosis based on where it is located in the body.

Major types of venous thrombosis include deep vein thrombosis, renal vein thrombosis, portal vein thrombosis, cerebral venous sinus thrombosis, etc.

Arterial thrombosis will usually occur as a result of an atheroma rupture in the arteries or due to stasis caused by atrial fibrillation in the heart.

Virchow’s triad is the triangle which describes the pathophysiology behind thrombus formation. This includes hypercoagulability of blood, injury to blood vessel walls and abnormal flow of blood in the vessels.

  • Hypercoagulability (thrombophilia) occurs due to a higher level of coagulation factors in the blood which ultimately increases the risk of thrombosis. This may be a result of genetic factors or pathologies of the immunity system.
  • Injury to endothelial cells on the blood vessel walls can take place following trauma, surgery or infection which will, in turn, initiate the blood coagulation in an overrated manner, giving rise to thrombosis.
  • Slowing down of the blood flow inside the blood vessels, also known as venous stasis, mostly follows heart failure, malignancies, arrhythmias and sedentary lifestyles including high-fat. These are also able to precipitate the blood coagulation in an excessive manner, resulting in Thrombosis.

Major complications of thrombus formation inside the body include hypoxia due to obstruction of blood vessels which perfuse important organs like lungs and brain. This will lead to a reduction of oxygen supply around the body, which will cause lactic acid formation, following anaerobic respiration.

Additionally, some of these blood clots can get detached from the vessel walls and travel to distant sites and lodge (embolization), resulting in an obstruction of oxygen supply to affected sites, causing ischemia, infarction or strokes, depending on the site of poor perfusion.

Thrombosis can be effectively treated with anti-platelets such as heparin and anti-coagulants, depending on the severity of the condition and underlying etiological conditions such as hyperlipidemia.Difference Between Haemostasis and Thrombosis

Difference Between Haemostasis and Thrombosis


Even though both these terms refer to a process of coagulation within the blood vessels, they are two different processes.

Haemostasis can be defined as a natural clotting mechanism which takes place to prevent excessive bleeding following an injury to the vessel wall.

Thrombosis occurs in an overrated manner often resulting in several complications such as embolization by causing obstructions inside vessels.


The major aetiology behind haemostasis includes the activation of a coagulation cascade following an injury to vessel walls.

The aetiology of thrombosis  consists of what is known as Virchow’s triad which describes factors contributing to the clot formation in an excessive manner including hypercoagulability, stasis, and injury to endothelium.

Image Courtesy:

“1909 Blood Clotting” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia

“Blood clot diagram” By en:User:Persian Poet Gal – (CC BY-SA 3.0) via Commons Wikimedia 

About the Author: Embogama

Embogama is a passionate freelance writer for several years. Her areas of interest include general medicine, clinical medicine, health and fitness, Ayurveda medicine, psychology, counseling and piano music