What Is A Blood Clot?

Blood is a fluid of life that transports oxygen and nutrients to all the parts of the body. Every organ requires blood as it cannot sustain itself without any blood supply. The brain dies within four to six minutes without any blood supply.

Whenever a trauma occurs it could result in the loss of blood and fluids that may later on lead the body into a shock. Therefore, the mechanism of blood clotting is present in the body to reduce blood loss. 

Blood clotting can result from both intrinsic and extrinsic pathways. There are many clotting factors and various other proteins that help in both the clotting and anti-clotting processes. Any imbalance in these cycles results in bleeding disorders. Excess bleeding or the formation of blood clots can be proven to be problematic. Blood clots clog the blood vessels and stop the blood flow to the particular organ. 

Blood clotting disorders result in blood changing from a liquid state to a gel-like state. This can be the result of many reasons including:

  • Damage to the vessel lining
  • Disturbance in the haemostasis balance
  • Slowing of the arterial or venous blood flow1


Blood clotting is a normal phenomenon to stop blood flow in case of trauma. It is a life-saving mechanism initiated by the body. It is done by various coagulation proteins. When the haemostasis balance is disturbed, blood clots will form to stop the flow of the blood supply to vital organs.

They can be formed in: 

  • Arteries- blood vessels that carry oxygenated blood to various organs from the heart
  • Veins- blood vessels that carry deoxygenated blood from different organs to the heart

When blood clots form in vessels supplying the legs, deep vein thrombosis (DVT) may occur resulting in the stoppage of blood supply to the peripheral parts. Blood clots formed in the lungs result in pulmonary embolism (PE), while in the heart, blood clots can result in the blockage of arteries, leading to a heart attack.

Causes of blood clot

Blood clot formation can be multifactorial, with the causes being either inherited or acquired: 

  • Inherited - examples of disorders include Antithrombin III deficiency, protein C and S deficiencies, factor V Leiden, and prothrombin gene mutations
  • Acquired - blood clots can be formed due to various reasons:
    • Medications—oral contraceptives, oestrogen or other hormonal replacements increase the oestrogen levels which in turn affects the fibrinogen and clotting factors that form blood clots
    • Acute inflammatory conditions—pregnancy, surgery, trauma, or infection
    • Chronic inflammatory conditions—heavy smoking, morbid obesity, rheumatologic disease or ulcerative colitis
    • Antiphospholipid syndrome—a condition in which antibodies attack normal proteins in the blood resulting in the formation of blood clots
    • Heparin-induced thrombocytopenia and thrombosis—heparin is used to treat blood clots. In some cases, it results in the reduction of platelets and hypercoagulability of blood, resulting in heparin-induced thrombocytopenia (HIT) and thrombosis
    • Malignancy—cancer and cancer medication increase the frequency of blood clotting, causing blood clots. Therefore, both are risk factors

Antithrombin and certain proteins, like protein C and protein S, are helpful in stopping the clotting process. When these are genetically deficient, the resulting condition involves a tendency for blood to clot. Inflammation initiates clotting and decreases natural anticoagulant action by impairing the fibrinolytic system.1

Signs and symptoms of blood clots

Blood clots form clogs in the respective blood vessels and result in:

  • Swelling
  • Redness
  • Pain

When blood clots are formed in vital organs like the lungs, they can cause: 

  • Shortness of breath
  • Chest Pain
  • Cough containing blood
  • Lightheadedness

When blood clots are formed in arteries and vessels supplying the heart, they can cause:

  • Lightheadedness
  • Shortness of breath
  • Chest pain
  • Nausea 
  • Sweating
  • Discomfort in the upper part of the body (arm, back, neck etc)

Diagnosis of blood clots

When someone encounters any of the symptoms of blood blots, it may be due to various health issues. One has to diagnose blood clots that result in such symptoms, by various techniques including: 

  • Duplex ultrasonography
  • Contrast venography
  • Laboratory investigations like D-dimer blood test
  • Computed tomography angiography
  • Ventilation/ perfusion imaging (V/Q scan)
  • Magnetic resonance imaging (MRI)
  • Pulmonary angiography

Management and treatment for blood clots

The management of blood clots can be achieved based on the blood vessels they are formed in. For venous blood clots, treatment is done by “blood thinners” (anticoagulants). Blood thinners don't make the blood thinner, but reduce the coagulability nature of blood, hence their name. 

For arterial blood clots, treatment is done with antiplatelet therapy. The surgical removal of blood clots is also possible.

To treat any blood clot, one has to assess the following factors:

  • Whether it is the first time or a recurrent case
  • Other risk factors contributing to blood clots
  • Extent of the blood clot
  • Persistence of symptoms in immediate cases or for prolonged periods

“Blood thinners” that are injectable include:

  • Unfractionated heparin (UFH)
  • Low molecular weight heparin (LMWH)
  • Fondaparinux (injected under the skin)

“Blood thinners” that are taken orally include:

  • Warfarin
  • Dabigatran
  • Rivaroxaban
  • Apixaban
  • Edoxaban

Thrombolytics, also called “clot-busters”, have a higher risk of causing bleeding compared to anticoagulants. Hence are only used for severe cases.

Inferior vena cava filters help to capture or trap any blood clot reaching the heart.

Surgical options for the removal of clots (including the use of a catheter) include:

  • Directed thrombolysis 
  • Percutaneous aspiration thrombectomy 
  • Venous balloon dilatation
  • Pharmacomechanical catheter-directed thrombolysis 


How are blood clots diagnosed?

Blood clots can be diagnosed clinically with symptoms of swelling, and pain in localised regions. Clots can also be diagnosed by ultrasonography. Duplex ultrasonography is a more reliable way to diagnose the presence of blood clots. Computed tomography of a particular region can also help in the diagnosis of a blood clot in the vessels.

How can I prevent blood clots?

You can lower your risk of blood clots by making small lifestyle changes like 

  • Staying active - a sedentary lifestyle for long periods of time can cause your blood to pool, which can lead to clots. It's better to move every 30 minutes to 1 hour to keep your blood moving
  • Regular exercise - exercising 30 minutes daily is a good way to have good blood circulation
  • Lose weight - being overweight can cause blood clots due to stagnation, therefore losing weight can help in the prevention of blood clots
  • If travelling, be extra cautious - being stagnant for many hours can cause a higher chance of blood clots, therefore it is better to make small, stretching movements while travelling
  • Drinking water - staying hydrated can help in the maintenance of good health
  • If pregnant, hormone changes cause more blood to clot, therefore keeping an active lifestyle during pregnancy can help
  • Keep feet raised when sleeping 
  • Watch for signs and symptoms of clot formation

Who are at risk of developing blood clots?

  • Those who have undergone surgery and hospitalisation are at a higher risk of blood clots 
  • Overweight persons, pregnant people and those with inflammatory conditions are more prone to developing blood clots
  • Patients with cancer or those receiving cancer treatment experience the activation of clotting factors, causing more blood clots
  • Relevant family history of blood clots also means there is a higher risk of thromboembolism
  • People assigned female at birth (AFAB) with cancer history have more tendency to form blood clots compared to people assigned male at birth (AMAB)
  • Studies have also demonstrated that European descendants are more prone rather than non-European descendants

How common are blood clots?

Deaths due to blood clots are common all over the globe. Deep vein thrombosis and pulmonary embolism have an incidence of  1 per 100,000 in children, 1 per 10,000 in reproductive ages, 1 per 1,000 in later/ middle ages, and 1 per 100 in elderly ages. There were 2294 deaths in 2019 which increased to 2638 in 2021.2294 deaths in 2019 which increased to 2638 in 2021.

When should I see a doctor?

It is better to visit a doctor whenever you see symptoms of blood clots. The blood clots can cause death in many cases if neglected.


Blood is essential for the proper function of all the organs in the body. Clotting of blood is a natural process that occurs to prevent excessive bleeding caused due to intrinsic or extrinsic pathways. The formation of blood clots is a defence mechanism developed in the body to protect this fluid of life (blood). This tendency of blood to form clots excessively can also cause many health issues that need to be addressed immediately. Even with the advancements in technology, the number of deaths due to blood clots was not controllable or reduced. This might be due to changes in the lifestyle patterns of modern man. Leading an active life with good physical activity and a proper intake of nutrients can lead to a good balance and overall health in the body, thereby reducing your chances of developing blood clots.


  1. Ashorobi D, Ameer MA, Fernandez R. Thrombosis. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing, 2022. PubMed.Available from: http://www.ncbi.nlm.nih.gov/books/NBK538430/ 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Swathi Gadadasu

I am Dr Swathi G, from India, with experience as a dental clinician for 8 years, oral physician and Oral Maxillofacial Radiologist for 4 years, an academician for 3.5 years, an academic writer for 3 years and a medical writer for 1 year. With sound knowledge of clinical, non-clinical, scientific and academic and medical writing, working as a Freelancer Writer at Work foster. Due to my passion for writing, completed many national and international Publications in various indexed and well-known journals.

Leave a Reply

Your email address will not be published. Required fields are marked *

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818