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Normally, if you get hurt, your body forms a blood clot to stop the bleeding. For blood to clot, your body needs cells called platelets and proteins known as clotting factors. If you have a bleeding disorder, you either do not have enough platelets or clotting factors or they don't work the way they should.

Bleeding disorders can be the result of other diseases, such as severe liver disease or a lack of vitamin K. They can also be inherited. Hemophilia is an inherited bleeding disorder. Bleeding disorders can also be a side effect of medicines such as blood thinners.

Various blood tests can check for a bleeding disorder. You will also have a physical exam and history. Treatments depend on the cause. They may include medicines and transfusions of blood, platelets, or clotting factor.

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.

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

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

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.

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

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.

Bleeding is the loss of blood. It can be external, or outside the body, like when you get a cut or wound. It can also be internal, or inside the body, like when you have an injury to an internal organ. Some bleeding, such as gastrointestinal bleeding, coughing up blood, or vaginal bleeding, can be a symptom of a disease.

Normally, when you are injured and start bleeding, a blood clot forms to stop the bleeding quickly. Afterwards, the clot dissolves naturally. To be able to make a clot, your blood needs blood proteins called clotting factors and a type of blood cell called platelets. Some people have a problem with clotting, due to another medical condition or an inherited disease. There are two types of problems:

• Your blood may not form clots normally, known as a bleeding disorder. This happens when your body does not make enough platelets or clotting factors, or they don't work the way they should.
• Your blood may make too many clots, or the clots may not dissolve properly

Sometimes bleeding can cause other problems. A bruise is bleeding under the skin. Some strokes are caused by bleeding in the brain. Severe bleeding may require first aid or a trip to the emergency room.

Blood thinners are medicines that prevent blood clots from forming. They do not break up clots that you already have. But they can stop those clots from getting bigger. It's important to treat blood clots, because clots in your blood vessels and heart can cause heart attacks, strokes, and blockages.

You may need a blood thinner if you have:

• Certain heart or blood vessel diseases
• An abnormal heart rhythm called atrial fibrillation
• A heart valve replacement
• A risk of blood clots after surgery
• Congenital heart defects

There are different types of blood thinners:

• Anticoagulants, such as heparin or warfarin (also called Coumadin), slow down your body's process of making clots.
• Antiplatelets, such as aspirin and clopidogrel, prevent blood cells called platelets from clumping together to form a clot. Antiplatelets are mainly taken by people who have had a heart attack or stroke.

When you take a blood thinner, follow the directions carefully. Blood thinners may interact with certain foods, medicines, vitamins, and alcohol. Make sure that your health care provider knows all of the medicines and supplements you are using.

You may need regular blood tests to check how well your blood is clotting. It is important to make sure that you're taking enough medicine to prevent clots, but not so much that it causes bleeding.

Bleeding is the most common side effect of blood thinners. They can also cause an upset stomach, nausea, and diarrhea.

Other possible side effects can depend on which type of blood thinner that you are taking.

Call your provider if you have any sign of serious bleeding, such as:

• Menstrual bleeding that is much heavier than normal
• Red or brown urine
• Bowel movements that are red or black
• Bleeding from the gums or nose that does not stop quickly
• Vomit that is brown or bright red
• Coughing up something red
• Severe pain, such as a headache or stomachache
• Unusual bruising
• A cut that does not stop bleeding
• A serious fall or bump on the head
• Dizziness or weakness

Hemophilia is a rare bleeding disorder in which the blood does not clot properly. This can lead to problems with bleeding too much after an injury or surgery. You can also have sudden bleeding inside your body, such as in your joints, muscles, and organs.

Your blood contains many proteins called clotting factors that can help form clots to stop bleeding. People with hemophilia have low levels of one of these factors, usually either factor VIII (8) or factor IX (9). How severe the hemophilia is depends on the amount of factor in the blood. The lower the amount of the factor, the more likely it is that bleeding could happen and might lead to serious health problems.

There are several different types of hemophilia. The most common are:

• Hemophilia A (classic hemophilia), which is caused by a lack or decrease of clotting factor VIII (8)
• Hemophilia B (Christmas disease), which is caused by a lack or decrease of clotting factor IX (9)

Most types of hemophilia are inherited. They are caused by change in one of the genes (also called a mutation) that provides instructions for making the clotting factor proteins. The change may mean that the clotting proteins don't work properly or that they are missing altogether.

These genes are on the X chromosome. You may have one or two X chromosomes:

• People who are born male have one X chromosome (from the mother) and one Y chromosome (from the father). They can get hemophilia if their one X chromosome has the gene change.
• People who are born female have two X chromosomes, one from the father and one from the mother. They usually only get hemophilia if:
  • Both X chromosomes have the gene change OR
  • One X chromosome has the gene change and the other X chromosome is missing or inactive.

  People who are born female who have the gene change on one X chromosome are a "carrier" of hemophilia. Sometimes they may have some symptoms of hemophilia. They can pass the gene change on to their children.

Hemophilia that is not inherited is called acquired hemophilia. It is rare. It happens when your body makes specialized proteins called autoantibodies that attack and disable a clotting factor. This can happen because of pregnancy, immune system disorders, cancer, or allergic reactions to certain medicines. Sometimes the cause is unknown.

Hemophilia is much more common in people who were born male since they can get it with a change to the gene on one X chromosome. People who have a family history of hemophilia are also at higher risk.

The signs and symptoms of hemophilia are:

• Bleeding into the joints. This can cause swelling and pain or tightness in the joints. It often affects the knees, elbows, and ankles.
• Bleeding into the skin (which is bruising).
• Bleeding into the muscle and soft tissue, which can cause a build-up of blood in the area (called a hematoma).
• Bleeding of the mouth and gums, including bleeding that is hard to stop after you lose a tooth.
• Bleeding after circumcision.
• Bleeding after having shots, such as vaccinations.
• Bleeding in the head of an infant after a difficult delivery.
• Blood in the urine or stool.
• Frequent and hard-to-stop nosebleeds.

In some cases, severe hemophilia may cause bleeding in the brain. This may cause brain damage and can be life-threatening.

To find out if you have hemophilia, your health care provider will:

• Ask about your medical history, including your symptoms and other health conditions you may have.
• Ask about your family history, to find out if you have relatives who have or had hemophilia.
• Do a physical exam to look for signs of hemophilia, such as bruising.
• Do certain blood tests to show if your blood is clotting properly. If it does not, then you will have clotting factor tests to diagnose the cause of the bleeding disorder. These blood tests would show the type of hemophilia and the severity.

There is genetic testing for the factor VIII (8) and factor IX (9) genes. This testing may be used in people who have a family history of hemophilia to:

• Identify people who are carriers before they make decisions about pregnancy
• Test a fetus for hemophilia during pregnancy
• Test a newborn for hemophilia

The best way to treat hemophilia is to replace the missing clotting factor so that your blood can clot properly. This is usually done by injecting replacement clotting factor into a vein. The replacement clotting factor may be made from donated human blood. Or it may be made in a lab; this kind is called a recombinant clotting factor.

Replacement clotting factor can help treat a bleeding episode. In more severe cases of hemophilia, you might get the factor on a regular basis to prevent bleeding. You can learn how to inject the factor so that you can do it yourself at home.

There are other medicines to treat hemophilia. They may work by releasing factor VIII (8) from where it is stored in the body tissues, replacing the function of factor VIII (8), or preventing clots from breaking down.

If bleeding has damaged your joints, physical therapy may help them function better.

Good quality medical care from healthcare professionals who know a lot about the disorder can help prevent some serious problems. Often the best choice for care is to visit a hemophilia treatment center (HTC).

Centers for Disease Control and Prevention