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What Is Thrombosis?

Thrombosis occurs when one or more blood clots develop in a blood vessel or the heart. A thrombus (clot) forms when blood cells stick together when they shouldn’t. A clot can grow large enough to stop blood from flowing through your circulatory system and create a life-threatening situation. Clots in deep veins, large arteries, or a pulmonary (lung) artery pose the greatest risk to your health.

Embolism vs. Thrombosis

A thrombus is a stationary blood clot. An embolus occurs when a piece of the blood clot moves to another part of your body. If the embolus becomes stuck in a blood vessel and cuts off blood flow, it’s called an embolism.

Thrombosis Symptoms

Thrombosis generally has no symptoms until the clot stops or significantly decreases blood flow. When you notice symptoms, you should seek medical attention quickly.

What Does Thrombosis Feel Like?

Symptoms of thrombosis differ depending on the clot’s location in the body. Blood clots in your legs may cause swelling, pain, and persistent cramping in the calf or thigh. It may feel like a charley horse (another term for a muscle spasm or cramp) that doesn’t go away with rest or stretching. A clot in your lungs or heart causes difficulty breathing, chest pain, tightness, dizziness, and low blood pressure. Clots in your lungs also cause coughing that can produce blood. When clots occur in your neck, head, or brain, you may experience stroke-like symptoms:

  • Sudden facial numbness
  • Arm and leg weakness
  • Confusion
  • Difficulty speaking
  • Loss of balance
  • Vision difficulties

Types of Thrombosis

The type of blood vessel involved identifies the type of thrombosis:

  • Venous thrombosis—This occurs in a vein, usually in the deep veins of the lower leg, thigh, pelvis, or arm.
  • Arterial thrombosis—This occurs in an artery, the blood vessels that carry oxygen-rich blood to your organs. If blood flow stops or slows, organs like the brain or heart are at risk of irreversible damage.
  • Coronary thrombosis—This means a blood clot is in an artery carrying blood to the heart. It restricts blood flow to and from the heart, causing tissue damage or a heart attack.

What Causes Thrombosis?

When you’re injured, your blood clumps together to naturally stop the bleeding, which creates a clot. In most cases, your body breaks down and reabsorbs the clot. However, a medical condition, medication, or lifestyle factors may prevent your body from dissolving the clot. Over time, the clot can grow and block the blood supply to your tissues and organs.

Thrombosis Risk Factors

Surgery is the biggest risk factor for thrombosis. However, some people are more likely to develop a blood clot due to the following risk factors:

  • Age over 65 years
  • Birth control pills and estrogen hormone therapy
  • Cancer and chemotherapy
  • Clotting disorders like antiphospholipid syndrome
  • Diabetes
  • Extended bed rest at home or in the hospital
  • Heart disease, including high blood pressure or heart failure
  • Injuries to the lower extremities
  • Lengthy trips in a car or plane (more than 4 hours)
  • Obesity
  • Personal or family history of blood clots
  • Pregnancy
  • Smoking

Thrombosis Diagnosis

Your provider will discuss your health history and perform a physical exam. They will also order tests to make a diagnosis:

  • Blood tests to measure proteins in your blood
  • Computed tomography (CT) or magnetic resonance imaging (MRI) scans to visualize clots
  • Ultrasound to assess the flow of blood in your arteries and veins
  • Venography to see blood flow using an X-ray.

Thrombosis Treatment

Most patients with thrombosis take anticoagulant medications (blood thinners) to help their body dissolve the blood clot. These medications are taken orally, by injection, or intravenously (through a vein). Some of the most common anticoagulant medications are warfarin, rivaroxaban, apixaban, and heparin. Your health care provider will assess your risk for future blood clots and determine how long you should continue taking the medication. Patients with life-threatening blood clots receive thrombolytics, a powerful medication that quickly breaks up the clot. If you have stroke or heart attack symptoms, call 911 or seek medical attention immediately.

Find a Thrombosis Specialist

Why Choose University of Utah Health?

U of U Health’s Thrombosis Service includes internal medicine providers, pharmacists, and support staff specializing in blood-clotting problems. Led by specialty-trained pharmacists, the team helps patients manage their blood thinner medications, ensuring effective treatment and reducing complications.

Additionally, our Thrombosis Service is an Anticoagulation Center of Excellence, meaning we offer the highest level of care and achieve the best patient outcomes.

How to Refer a Patient to the Thrombosis Service

Only U of U Health providers can refer patients to the Thrombosis Service, such as referrals for anticoagulation monitoring for medication management or E-consult to thrombosis for complex clinical questions. Please send the appropriate order via the patient’s electronic health record. To learn more, please call 801-213-9150.