Many people who have or have had family members with hemophilia will ask that their baby boys get tested soon after birth.
About one-third of babies who are diagnosed with hemophilia have no other family members with the disorder. A doctor might check for hemophilia if a newborn is showing certain signs of hemophilia.
Diagnosis includes screening tests and clotting factor tests. Screening tests are blood tests that show if the blood is clotting properly. Clotting factor tests, also called factor assays, are required to diagnose a bleeding disorder. This blood test shows the type of hemophilia and the severity.
Families With a History of Hemophilia
Any family history of bleeding, such as following surgery or injury, or unexplained deaths among brothers, sisters, or other male relatives such as maternal uncles, grandfathers, or cousins should be discussed with a doctor to see if hemophilia was a cause. A doctor often will get a thorough family history to find out if a bleeding disorder exists in the family.
Many people who have or have had family members with hemophilia will ask that their baby boys get tested soon after birth. In the best of cases, testing for hemophilia is planned before the baby’s delivery so that a sample of blood can be drawn from the umbilical cord (which connects the mother and baby before birth) immediately after birth and tested to determine the level of the clotting factors. Umbilical cord blood testing is better at finding low levels of factor VIII (8) than it is at finding low levels of factor IX (9). This is because factor IX (9) levels take more time to develop and are not at a normal level until a baby is at least 6 months of age. Therefore, a mildly low level of factor IX (9) at birth does not necessarily mean that the baby has hemophilia B. A repeat test when the baby is older might be needed in some cases. Learn more about the inheritance pattern for hemophilia.
Families With No Previous History of Hemophilia
About one-third of babies who are diagnosed with hemophilia have no other family members with the disorder. A doctor might check for hemophilia in a newborn if:
- Bleeding after circumcision of the penis goes on for a long time.
- Bleeding goes on for a long time after drawing blood and heel sticks (pricking the infant’s heel to draw blood for newborn screening tests).
- Bleeding in the head (scalp or brain) after a difficult delivery or after using special devices or instruments to help deliver the baby (e.g., vacuum or forceps).
- Unusual raised bruises or large numbers of bruises. If a child is not diagnosed with hemophilia during the newborn period, the family might notice unusual bruising once the child begins standing or crawling.
Those with severe hemophilia can have serious bleeding problems right away. Thus, they often are diagnosed during the first year of life. People with milder forms of hemophilia might not be diagnosed until later in life.
Screening tests are blood tests that show if the blood is clotting properly. Types of screening tests:
Complete Blood Count (CBC)
This common test measures the amount of hemoglobin (the red pigment inside red blood cells that carries oxygen), the size and number of red blood cells and numbers of different types of white blood cells and platelets found in blood. The CBC is normal in people with hemophilia. However, if a person with hemophilia has unusually heavy bleeding or bleeds for a long time, the hemoglobin and the red blood cell count can be low.
Activated Partial Thromboplastin Time (APTT) Test
This test measures how long it takes for blood to clot. It measures the clotting ability of factors VIII (8), IX (9), XI (11), and XII (12). If any of these clotting factors are too low, it takes longer than normal for the blood to clot. The results of this test will show a longer clotting time among people with hemophilia A or B.
Prothrombin Time (PT) Test
This test also measures the time it takes for blood to clot. It measures primarily the clotting ability of factors I (1), II (2), V (5), VII (7), and X (10). If any of these factors are too low, it takes longer than normal for the blood to clot. The results of this test will be normal among most people with hemophilia A and B.
This test also helps doctors assess a patient’s ability to form a blood clot. This test is ordered either along with other blood clotting tests or when a patient has an abnormal PT or APTT test result, or both. Fibrinogen is another name for clotting factor I (1).
Clotting Factor Tests
Clotting factor tests, also called factor assays, are required to diagnose a bleeding disorder. This blood test shows the type of hemophilia and the severity. It is important to know the type and severity in order to create the best treatment plan.
Levels of Factor VIII (8)
Normal (person who does not have hemophilia)
50% to 100%
Greater than 5% but less than 50%
1% to 5%
Less than 1%
- Centers for Disease Control and Prevention
National Center on Birth Defects and Developmental Disabilities
Division of Blood Disorders
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