Bleeding is the loss of blood. It can happen outside or inside the body. You may bleed when you get a cut or other wound. Bleeding can also be due to an injury to internal organs.

Sometimes bleeding can cause other problems. A bruise is bleeding under the skin. Some strokes are caused by bleeding in the brain. Other bleeding, such as gastrointestinal bleeding, coughing up blood, or vaginal bleeding, can be a symptom of a disease.

Normally, when you bleed, your blood forms clots to stop the bleeding. Severe bleeding may require first aid or a trip to the emergency room. If you have a bleeding disorder, your blood does not form clots normally.

A collection of blood outside the BLOOD VESSELS. Hematoma can be localized in an organ, space, or tissue.

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.

Bleeding disorders are rare disorders affecting the way the body controls blood clotting. If your blood does not clot normally, you may experience problems with bleeding too much after an injury or surgery. This health topic will focus on bleeding disorders that are caused by problems with clotting factors, including hemophilia and von Willebrand disease.

Clotting factors, also called coagulation factors, are proteins in the blood that work with small cells, called platelets, to form blood clots. Any problem that affects the function or number of clotting factors or platelets can lead to a bleeding disorder.

A bleeding disorder can be inherited, meaning that you are born with the disorder, or it can be acquired, meaning it develops during your life. Signs and symptoms can include easy bruising, heavy menstrual periods, and frequent nosebleeds that happen often. Your doctor will review your symptoms, risk factors, medical history, and blood test results to diagnose a bleeding disorder.

Your doctor may recommend medicines or clotting factor replacement therapy to treat the bleeding disorder. Some bleeding disorders are lifelong conditions, and some can lead to complications. Even if you do not need medicine to treat the bleeding disorder, your doctor may recommend taking precautions before a medical procedure or during a pregnancy to prevent bleeding problems in the future.

Hemophilia is a rare disorder in which the blood does not clot normally. It is usually inherited. Hemophilia usually occurs in males.

If you have hemophilia, you have little or no clotting factor. Clotting factor is a protein needed for normal blood clotting. Without it, you may bleed for a long time after an injury or accident. You also may bleed into your knees, ankles, and elbows. Bleeding in the joints causes pain and, if not treated, can lead to arthritis. Bleeding in the brain, a very serious complication of hemophilia, requires emergency treatment.

The main symptoms of hemophilia are excessive bleeding and easy bruising. Blood tests can tell if you have it. The main treatment is injecting the missing clotting factor into the bloodstream. You may need it on a regular basis, or just when bleeding occurs.

Your blood is made up of liquid and solids. The liquid part, called plasma, is made of water, salts, and protein. Over half of your blood is plasma. The solid part of your blood contains red blood cells, white blood cells, and platelets.

Red blood cells (RBC) deliver oxygen from your lungs to your tissues and organs. White blood cells (WBC) fight infection and are part of your immune system. Platelets help blood to clot when you have a cut or wound. Bone marrow, the spongy material inside your bones, makes new blood cells. Blood cells constantly die and your body makes new ones. Red blood cells live about 120 days, and platelets live about 6 days. Some white blood cells live less than a day, but others live much longer.

There are four blood types: A, B, AB, or O. Also, blood is either Rh-positive or Rh-negative. So if you have type A blood, it's either A positive or A negative. Which type you are is important if you need a blood transfusion. And your Rh factor could be important if you become pregnant - an incompatibility between your type and the baby's could create problems.

Blood tests such as blood count tests help doctors check for certain diseases and conditions. They also help check the function of your organs and show how well treatments are working. Problems with your blood may include bleeding disorders, excessive clotting and platelet disorders. If you lose too much blood, you may need a transfusion.

What is a blood clot?

A blood clot is 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 can happen when a DVT breaks off and travels through the bloodstream to the lungs. It 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 at risk for blood clots?

Certain factors can raise the risk of blood clots:

• Atherosclerosis
• Atrial fibrillation
• 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?

Your health care provider may use many tools to diagnose blood clots:

• A physical exam
• A medical history
• Blood tests, including a D-dimer test
• 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 which 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
• 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.

Blood thinners are medicines that prevent blood clots from forming. They also keep existing blood clots from getting larger. Clots in your arteries, veins, and heart can cause heart attacks, strokes, and blockages. You may take 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 two main types of blood thinners. Anticoagulants such as heparin or warfarin (also called Coumadin) slow down your body's process of making clots. Antiplatelet drugs, such as aspirin, prevent blood cells called platelets from clumping together to form a clot.

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

Your blood is living tissue made up of liquid and solids. The liquid part, called plasma, is made of water, salts and protein. Over half of your blood is plasma. The solid part of your blood contains red blood cells, white blood cells and platelets.

Blood disorders affect one or more parts of the blood and prevent your blood from doing its job. They can be acute or chronic. Many blood disorders are inherited. Other causes include other diseases, side effects of medicines, and a lack of certain nutrients in your diet.

Types of blood disorders include

• Platelet disorders, excessive clotting, and bleeding problems, which affect how your blood clots
• Anemia, which happens when your blood does not carry enough oxygen to the rest of your body
• Cancers of the blood, such as leukemia and myeloma
• Eosinophilic disorders, which are problems with one type of white blood cell.

If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough iron. Your body needs iron to make hemoglobin. Hemoglobin is an iron-rich protein that gives the red color to blood. It carries oxygen from the lungs to the rest of the body.

Anemia has three main causes: blood loss, lack of red blood cell production, and high rates of red blood cell destruction.

Conditions that may lead to anemia include

• Heavy periods
• Pregnancy
• Ulcers
• Colon polyps or colon cancer
• Inherited disorders
• A diet that does not have enough iron, folic acid or vitamin B12
• Blood disorders such as sickle cell anemia and thalassemia, or cancer
• Aplastic anemia, a condition that can be inherited or acquired
• G6PD deficiency, a metabolic disorder

Anemia can make you feel tired, cold, dizzy, and irritable. You may be short of breath or have a headache.

Your doctor will diagnose anemia with a physical exam and blood tests. Treatment depends on the kind of anemia you have.

Your blood contains red blood cells (RBC), white blood cells (WBC), and platelets. Blood count tests measure the number and types of cells in your blood. This helps doctors check on your overall health. The tests can also help to diagnose diseases and conditions such as anemia, infections, clotting problems, blood cancers, and immune system disorders.

Specific types include tests for

• RBC - the numbers, size, and types of RBC in the blood
• WBC - the numbers and types of WBC in the blood
• Platelets - the numbers and size of the platelets
• Hemoglobin - an iron-rich protein in red blood cells that carries oxygen
• Hematocrit - how much space red blood cells take up in your blood
• Reticulocyte count - how many young red blood cells are in your blood
• Mean corpuscular volume (MCV) - the average size of your red blood cells

The complete blood count (CBC) includes most or all of these. The CBC is one of the most common blood tests.

Every year, millions of people in the United States receive life-saving blood transfusions. During a transfusion, you receive whole blood or parts of blood such as

• Red blood cells - cells that carry oxygen to and from tissues and organs
• Platelets - cells that form clots to control bleeding
• Plasma - the liquid part of the blood that helps clotting. You may need it if you have been badly burned, have liver failure or a severe infection.

Most blood transfusions go very smoothly. Some infectious agents, such as HIV, can survive in blood and infect the person receiving the blood transfusion. To keep blood safe, blood banks carefully screen donated blood. The risk of catching a virus from a blood transfusion is low.

Sometimes it is possible to have a transfusion of your own blood. During surgery, you may need a blood transfusion because of blood loss. If you are having a surgery that you're able to schedule months in advance, your doctor may ask whether you would like to use your own blood, instead of donated blood. If so, you will need to have blood drawn one or more times before the surgery. A blood bank will store your blood for your use.

Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:

• White blood cells help your body fight infection
• Red blood cells deliver oxygen from your lungs to your tissues and organs
• Platelets help form clots to stop bleeding

When you have leukemia, your bone marrow makes large numbers of abnormal cells. This problem most often happens with white blood cells. These abnormal cells build up in your bone marrow and blood. They crowd out the healthy blood cells and make it hard for your cells and blood to do their work.

Eosinophils are a type of white blood cell. They help fight off infections and play a role in your body's immune response. They can also build up and cause inflammation.

Normally your blood doesn't have a large number of eosinophils. Your body may produce more of them in response to

• Allergic disorders
• Skin conditions
• Parasitic and fungal infections
• Autoimmune diseases
• Some cancers
• Bone marrow disorders

In some conditions, the eosinophils can move outside the bloodstream and build up in organs and tissues. This can happen in many different parts of the body, including the esophagus, heart, lungs, blood, and intestines. Treatment of eosinophilic disorders can vary, depending on the cause and which part of the body is affected. Steroids are often part of the treatment.

Hemochromatosis is a disease in which too much iron builds up in your body. Your body needs iron but too much of it is toxic. If you have hemochromatosis, you absorb more iron than you need. Your body has no natural way to get rid of the extra iron. It stores it in body tissues, especially the liver, heart, and pancreas. The extra iron can damage your organs. Without treatment, it can cause your organs to fail.

There are two types of hemochromatosis. Primary hemochromatosis is an inherited disease. Secondary hemochromatosis is usually the result of something else, such as anemia, thalassemia, liver disease, or blood transfusions.

Many symptoms of hemochromatosis are similar to those of other diseases. Not everyone has symptoms. If you do, you may have joint pain, fatigue, general weakness, weight loss, and stomach pain.

Your doctor will diagnose hemochromatosis based on your medical and family histories, a physical exam, and the results from tests and procedures. Treatments include removing blood (and iron) from your body, medicines, and changes in your diet.

There are four major blood types: A, B, O, and AB. The types are based on substances on the surface of the blood cells. Another blood type is called Rh. Rh factor is a protein on red blood cells. Most people are Rh-positive; they have Rh factor. Rh-negative people don't have it. Rh factor is inherited through genes.

When you're pregnant, blood from your baby can cross into your bloodstream, especially during delivery. If you're Rh-negative and your baby is Rh-positive, your body will react to the baby's blood as a foreign substance. It will create antibodies (proteins) against the baby's blood. These antibodies usually don't cause problems during a first pregnancy.

But Rh incompatibility may cause problems in later pregnancies, if the baby is Rh-positive. This is because the antibodies stay in your body once they have formed. The antibodies can cross the placenta and attack the baby's red blood cells. The baby could get Rh disease, a serious condition that can cause a serious type of anemia.

Blood tests can tell whether you have Rh factor and whether your body has made antibodies. Injections of a medicine called Rh immune globulin can keep your body from making Rh antibodies. It helps prevent the problems of Rh incompatibility. If treatment is needed for the baby, it can include supplements to help the body to make red blood cells and blood transfusions.

Thalassemias are inherited blood disorders. If you have one, your body makes fewer healthy red blood cells and less hemoglobin. Hemoglobin is a protein that carries oxygen to the body. That leads to anemia. Thalassemias occur most often among people of Italian, Greek, Middle Eastern, Southern Asian, and African descent.

Thalassemias can be mild or severe. Some people have no symptoms or mild anemia. The most common severe type in the United States is called Cooley's anemia. It usually appears during the first two years of life. People with it may have severe anemia, slowed growth and delayed puberty, and problems with the spleen, liver, heart, or bones.

Doctors diagnose thalassemias using blood tests. Treatments include blood transfusions and treatment to remove excess iron from the body. If you have mild symptoms or no symptoms, you may not need treatment. In some severe cases, you may need a bone marrow transplant.