Before we begin: Your blood forms clots to stop bleeding. Some people get too many clots or their blood clots abnormally. Learn about the causes and treatments.
This tutorial walks you through everything you need to know about blood clots. We explain it in plain language, step by step, so whether you are a student, a patient, or simply curious, you will come away with a solid understanding.
We cover what it is, why it matters, how it is diagnosed, and what you can do about it. Key facts are called out along the way.
What is a blood clot? A blood clot is a mass of blood that forms when platelets, proteins, and cells in the blood stick together. When you get hurt, your body forms a blood clot to stop the bleeding. After the bleeding stops and healing takes place, your body usually breaks down and removes the blood clot. But sometimes the blood clots form where they shouldn’t, your body makes too many blood clots or abnormal blood clots, or the blood clots don’t break down like they should. These blood clots can be dangerous and may cause other health problems.
Blood clots can form in, or travel to, the blood vessels in the limbs, lungs, brain, heart, and kidneys. The types of problems blood clots can cause will depend on where they are:
Deep vein thrombosis (DVT) is a blood clot in a deep vein, usually in the lower leg, thigh, or pelvis. It can block a vein and cause damage to your leg.
A pulmonary embolism (PE) can happen when a DVT breaks off and travels through the bloodstream to the lungs. A PE, especially if it is large, can damage your lungs and prevent your other organs from getting enough oxygen.
Cerebral venous sinus thrombosis (CVST) is a rare blood clot in the venous sinuses in your brain. Normally the venous sinuses drain blood from your brain. CVST blocks the blood from draining and can cause a hemorrhagic stroke.
Blood clots in other parts of the body can cause problems such as an ischemic stroke, a heart attack, kidney problems, kidney failure, and pregnancy-related problems.
Who is more likely to develop blood clots? Certain factors can raise your risk of developing blood clots:
Atherosclerosis
Atrial fibrillation
Being overweight or having obesity
Cancer and cancer treatments
Certain genetic disorders
Certain surgeries
COVID-19
Diabetes
Family history of blood clots
Overweight and obesity
Pregnancy and giving birth
Serious injuries
Some medicines, including birth control pills
Smoking
Staying in one position for a long time, such as being in the hospital or taking a long car or plane ride
What are the symptoms of blood clots? The symptoms for blood clots can be different, depending on where the blood clot is:
In the abdomen: Abdominal pain, nausea and vomiting
In an arm or leg: Sudden or gradual pain, swelling, tenderness, and warmth
In the lungs: Shortness of breath, pain with deep breathing, rapid breathing, and increased heart rate
In the brain: Trouble speaking, vision problems, seizures, weakness on one side of the body, and sudden severe headache
In the heart: Chest pain, sweating, shortness of breath, and pain in the left arm
How are blood clots diagnosed? To find out if you have one or more blood clots, your health care provider:
Will do a physical exam.
Will take your medical history, which includes asking about your symptoms.
May order blood tests, including a D-dimer test.
May order imaging tests, such as
Ultrasound.
X-rays of the veins (venography) or blood vessels (angiography) that are taken after you get an injection of special dye. The dye shows up on the x-ray and allows the provider to see how the blood flows.
CT Scan.
What are the treatments for blood clots? Treatments for blood clots depend on where the blood clot is located and how severe it is. Treatments may include:
Blood thinners.
Other medicines, including thrombolytics. Thrombolytics are medicines that dissolve blood clots. They are usually used where the blood clots are severe.
Surgery and other procedures to remove the blood clots
Can blood clots be prevented? You may be able to help prevent blood clots by:
Moving around as soon as possible after having been confined to your bed, such as after surgery, illness, or injury
Getting up and moving around every few hours when you have to sit for long periods of time, for example if you are on a long flight or car trip
Wearing compression stockings after surgery or during a long flight
Regular physical activity
Not smoking
Staying at a healthy weight
Some people at high risk may need to take blood thinners to prevent blood clots.
Also known as: Hypercoagulability.
Related topics: Thrombophlebitis, Venous Thrombosis.
Categories: Blood, Heart and Circulation.
Source: National Institutes of Health — National Heart, Lung, and Blood Institute.
Key Takeaways
Understanding blood clots is an important part of taking charge of your health. Here is what to remember:
- Know the signs — Recognizing early symptoms can lead to earlier diagnosis and better outcomes.
- Talk to your provider — If you have concerns or a family history of this condition, bring it up at your next checkup.
- Stay informed — Medical knowledge evolves. Keep learning and asking questions.
- You are not alone — Many people deal with this condition. Support groups and educational resources can help.