Thrombosis occurs when blood clots block your blood vessels. It may be caused by injury, immobility and other factors.
Hemophilia and Thrombosis Treatment Center - Pediatric
The Hemophilia and Thrombosis Center federally supported and fully accredited to offer comprehensive evaluations and individualized care for children and adults with bleeding and clotting disorders across their lifespan.
Pediatric Blood Disorders Program
The Pediatric Blood Disorders Program at Mass General for Children provides personalized multidisciplinary, state-of-the-art care to children of all ages with blood disorders.
Pediatric Stroke and Cerebrovascular Program
The Pediatric Stroke and Cerebrovascular Program at Mass General for Children cares for premature infants, children or adolescents who have had an ischemic or hemorrhagic stroke, or cerebral venous sinus thrombosis.
What is thrombosis?
Thrombosis occurs when blood clots block your blood vessels. There are 2 main types of thrombosis:
Venous thrombosis is when the blood clot blocks a vein. Veins carry blood from the body back into the heart.
Arterial thrombosis is when the blood clot blocks an artery. Arteries carry oxygen-rich blood away from the heart to the body.
What causes thrombosis?
Venous thrombosis may be caused by:
Disease or injury to the leg veins
Not being able to move around (immobility) for any reason
A broken bone (fracture)
Inherited disorders, or a greater likelihood of having a certain disorder based on your genes
Autoimmune disorders that make it more likely your blood will clot
Medicines that increase your risk of clotting (such as certain birth control medicines)
Arterial thrombosis may be caused by a hardening of the arteries (atherosclerosis). This happens when fatty or calcium deposits cause artery walls to thicken. This can lead to a buildup of fatty material (plaque) in the artery walls. This plaque can suddenly burst (rupture), followed by a blood clot.
Arterial thrombosis can occur in the arteries that supply blood to the heart muscle (coronary arteries). This can lead to a heart attack. When arterial thrombosis occurs in a blood vessel in the brain, it can lead to a stroke.
Who is at risk for thrombosis?
Many of the risk factors for venous and arterial thrombosis are the same.
Risk factors for venous thrombosis may include:
A family history of a blood clot in a vein deep in the body (deep vein thrombosis or DVT)
A history of DVT
Hormone therapy or birth control pills
Injury to a vein, such as from surgery, a broken bone, or other trauma
Lack of movement, such as after surgery or on a long trip
Inherited blood clotting disorders
A central venous catheter
Being overweight or obese
Some health conditions, such as cancer, heart disease, lung disease, or Crohn's disease
Risk factors for arterial thrombosis may include:
High blood pressure
Lack of activity and obesity
Family history of arterial thrombosis
Lack of movement, such as after surgery or on a long trip
What are the symptoms of thrombosis?
Symptoms may vary a bit for each person. Symptoms may include:
Pain in one leg, usually the calf or inner thigh
Swelling in the leg or arm
Numbness or weakness on one side of the body
Sudden change in your mental state
Cold arm or leg
The symptoms of thrombosis may look like other blood disorders or health problems. Always see your healthcare provider for a diagnosis.
How is thrombosis diagnosed?
Your healthcare provider will ask about your health history and give you a physical exam. Other tests may include:
Ultrasound. This test uses sound waves to check the blood flow in your arteries and veins.
Blood tests. These may include tests to see how well your blood can clot.
Venography. For this test, a dye is injected into your veins. Then X-rays are taken to show blood flow and look for clots. The dye makes your veins easier to see on the X-rays.
MRI, MRA, or CT scan. The imaging procedure that is used will depend on the type of blood clot you have and where it is located.
Angiography. This imaging test uses a contrast dye to look at the blood vessels.
How is thrombosis treated?
Treatment may include:
Blood-thinning medicines (anticoagulants)
Thin tubes (catheters) to widen the affected vessels
A wire mesh tube (stent) that holds a blood vessel open and stops it from closing
Medicines to interfere with or dissolve blood clots
Surgery to remove the blood clot
Your healthcare provider may advise other treatments.
What are possible complications of thrombosis?
Thrombosis can block the blood flow in both veins and arteries. Complications depend on where the thrombosis is located. Complications may include:
Sudden shortness of breath
Loss of organ function
Loss of limb
Can thrombosis be prevented?
You can reduce your thrombosis risk by:
Getting back to activity as soon as possible after surgery
Exercising your legs during long trips
Managing other health problems such as diabetes, high blood pressure, and high cholesterol
Key points about thrombosis
Thrombosis occurs when blood clots block veins or arteries.
Symptoms include pain and swelling in one leg, chest pain, or numbness on one side of the body.
Complications of thrombosis can be life-threatening, such as a stroke or heart attack.
Treatment includes medicines that thin the blood or prevent clots, and using stents or catheters to open blocked vessels.
Prevention includes being active, quitting smoking, losing weight, and managing other health conditions.
Tips to help you get the most from a visit to your healthcare provider:
Know the reason for your visit and what you want to happen.
Before your visit, write down questions you want answered.
Bring someone with you to help you ask questions and remember what your provider tells you.
At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
Ask if your condition can be treated in other ways.
Know why a test or procedure is advised and what the results could mean.
Know what to expect if you do not take the medicine or have the test or procedure.
If you have a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your provider if you have questions.
News & Publications
Quantity and Characteristics of Waste at a Level I Trauma Center
The purpose of this study was to quantify and describe the amount of waste generated by an Emergency Department, identify deviations from waste policy and explore areas for waste reduction.
The Climate-Smart Emergency Department: A Primer
Our publication keeps health care professionals up to date on the latest research and clinical advances from Mass General.
Research Institute Blog
News and notes from the largest hospital-based research program in the United States
A podcast devoted to uncovering the stories of Mass General's relentless pursuit to break boundaries and provide exceptional care
The Patient Gateway provides secure online access to your health information whenever you need it. Check upcoming appointments, communicate with your doctor’s office, review medications and pay medical bills—all seamlessly online 24/7.