Blood clots

Blood clots (thrombi), are clumps of blood that have changed from a liquid to a gel. That transformation (coagulation) happens to stop damaged blood vessels from leaking blood, either at the skin or inside the body. A type of blood cell called platelets and proteins called clotting factors work together to form clots and stop bleeding.

Normally, blood clots safely dissolve, or break up, when they’re no longer needed. Occasionally, though, clots block blood vessels or travel through them to a different part of the body. These clots are called emboli.

When this happens, blood clots may cause medical problems that may require prompt care:

• Arterial embolism, a clot that travels through an artery and then stops blood supply to an organ or other body part
• Deep vein thrombosis (DVT), a clot in veins (vessels returning blood to the heart) that typically forms in the legs and sometimes in the arms
• Heart attack from a clot forming to repair a damaged vessel near the heart and then blocking that blood supply
• Pulmonary embolism (PE) from a clot that travels from a vein into the heart and then toward the lungs, blocking their blood supply
• Stroke from a blood clot moving into an artery supplying the brain with blood and stopping the flow
• Thrombophlebitis, or swelling from a blood clot blocking a vein

Certain conditions, medications, and habits can increase the chances of these complications. Clots may not dissolve normally or form when they’re not needed, increasing the potential for trouble. These unwanted clots can develop in veins, arteries, or both.

When blood clots normally, you usually don’t notice it. If clots do not dissolve as they should or move to areas where they can cause problems, you can develop symptoms.

Blood clot signs you may experience vary by location:

• Arms and legs: Pain or tenderness, swelling, or warm feeling
• Brain: Trouble speaking; vision changes; sudden, strong headache; dizziness; or weakness in face, arms, or legs
• Heart: Pain in the chest or other part of the upper body, breathing difficulties, sweating, nausea, or light-headedness
• Lungs: Chest pain, difficulty breathing, rapid heartbeat, sweating, fever, or coughing up blood

Blood clots form as the body’s way of stopping bleeding from damaged blood vessels and promoting healing. They can develop in response to an injury or the trauma your body experiences during surgeries or other medical procedures. They can also form because of damage to arteries called atherosclerosis.

Blood clots can also linger, or form even when you haven’t been injured. The chances of developing these unusual blood clots can rise for a number of reasons, with some factors introducing higher risk than others:

• Age, with people over 60 at higher risk
• Blood clotting disorders, either inherited from parents or acquired after birth for other reasons
• Certain medical conditions, including atrial fibrillation, cancer, chronic inflammation, diabetes, hypertension (high blood pressure), high cholesterol, and obesity
• Estrogen, either from pregnancy, birth control, or hormone-replacement therapy
• Inactivity, such as bed rest or being confined during travel
• Pregnancy, which raises clotting factors to control expected bleeding
• Smoking

Doctors use several methods to find suspected blood clots and determine the possible cause:

• Physical exam and discussion: The doctor will check your body and ask about your history of clotting, as well as your risk factors.
• Blood work: Tests can evaluate various aspects of blood, including levels of clotting factors and each blood cell type.
• Imaging: Special forms of ultrasound and computed tomography (CT) can help doctors locate the clot.

Blood clot treatment depends on the clot’s location, how much danger it poses and how immediately it needs care. Urgent clots are sometimes treated with thrombolytic drugs (“clot-busters”) or removal with medical procedures.

For less urgent clots, your doctor may prescribe blood thinners, either anticoagulants for clotting factor problems or antiplatelets for platelet issues. Your doctor may also discuss other ways to lower your future risk.

The specialists involved in your care may include cardiologists, hematologists, interventional pulmonologists, interventional radiologists, neurologists, or vascular surgeons. Learn more about specific blood clot treatments:

• Blood clotting disorder treatment
• Deep vein thrombosis treatment
• Thrombolytic therapy