Hemophilia B is a blood clotting disorder (hemophilia) is caused by a deficiency of the blood clotting protein factor IX (or factor 9).
There are three types of hemophilia. The two most common types, hemophilia A and hemophilia B, are similar in that they often experience heavy bleeding or bruising after minor injuries, dental procedures, or surgery; bleeding from the gums or nose; or spontaneous joints Bleeding, especially from ankles, knees, and elbows.
If hemophilia is suspected, it is important to seek diagnosis and treatment as soon as possible to avoid any complications from untreated bleeding events.
Many other diseases have similar symptoms to hemophilia B, so your healthcare provider must take a detailed medical history, conduct a thorough physical examination, and request specialized laboratory, imaging, and blood tests to make a timely and accurate diagnosis.
This article will discuss the diagnostic process.
The first signs of hemophilia usually occur in childhood. Babies sometimes experience prolonged bleeding after routine vaccinations or vitamin K injections at birth. Or parents may notice that the bruise doesn’t go away after a minor fall, or that the wound heals slowly.
Parents who suspect that their child may have hemophilia can examine the child’s body for any other signs of bruising or swelling, and ask the family if they know of other relatives who have experienced the same.
A healthcare provider will take a detailed medical history prior to a physical exam. They may start by asking about your age, gender identity, and pronouns you use.
Next, they will ask about your symptoms, also known as your chief complaints. A detailed medical history is critical to making an accurate diagnosis, so your provider may also ask you the following questions:
- birth history
- History of bleeding, including type and location of bleeding, and history of prolonged or spontaneous bleeding following any minor injury.you may be referred to hematologist (a doctor who specializes in blood disorders) who may ask you about excessive bruising and/or bleeding during medical procedures such as immunizations.
- Family history, especially any genetic disease or long-term bleeding in family members
- recent trauma or surgery
- Immunization history
During the physical exam, your healthcare provider will look for bruising, pallor (morbid pallor), joint deformities, and limb/joint asymmetry. They may look for signs of swelling, such as areas of skin discoloration, and ask if you feel warmth or pain anywhere on your body.
Next, the healthcare provider may palpate (feel through the body) the elbows, wrists, knees, ankles, and neck or muscles (most commonly quadriceps, hamstrings, iliopsoas) , biceps and triceps).
Your healthcare provider may also move or ask you to move your limbs to assess range of motion (how far a body part can move or stretch) and pain with movement.Limited range of motion and signs of joint swelling may raise clinical suspicion hemoarthrosisa common symptom of hemophilia B.
Labs and Testing
Your healthcare provider will order several blood tests, including a complete blood count (CBC), clotting tests to check the function of clotting factors, tests to assess bleeding time, and genetic testing if necessary.
If hemophilia B is suspected based on symptoms, early blood tests, and blood clotting tests, a more specialized blood test to measure factor IX, called a factor IX (FIX) assay, may be ordered to measure levels of this specific blood clotting protein.
The following FIX levels indicate the severity of hemophilia B:
- Mild: More than 5%–40% of normal in plasma. This usually causes bleeding only after a serious injury, trauma, or surgery. In many cases, people with mild hemophilia don’t know they have the disease and only find out after prolonged bleeding from injury, surgery, or tooth extraction.Women with mild hemophilia often experience menorrhagiaMenorrhagia, postpartum bleeding may occur.
- Moderate: About 1%–5% of normal. People with this type of hemophilia B may experience bleeding episodes or spontaneous bleeding episodes after injury, but even this small amount of FIX can help avoid life-threatening bleeding episodes.
- Severe: less than 1% of normal levels in plasma.People with severe hemophilia B bleed after an injury and may often have spontaneous bleeding, usually to their joints and muscles
Once a person has been diagnosed with hemophilia B, genetic testing can also be done to look for the specific mutation in the F9 gene that causes your hemophilia B.
Although imaging is not required to diagnose hemophilia B, it can help with early detection and management of symptoms.The hallmark symptom of hemophilia B is bleeding, especially from the joints and/or soft tissue, also known as hemoarthrosis.
If left untreated, hemoarthrosis can lead to contracture (stiff joints and muscles) and limited range of motion. The following imaging modalities can be used to detect hidden bleeding in people with hemophilia B:
- musculoskeletal ultrasound (MSKUS): Ultrasound is a fast, efficient, safe, and cost-effective imaging type for early detection and management of hemoarthrosis. It can detect joint bleeding, synovial hypertrophy (enlargement of the membrane around the joint, indicating inflammation), cartilage damage, and muscle bruising (hematoma).
- X-rays: X-rays can identify irregularities in the joint space, joint effusion, and overgrowth of the epiphysis (ends of long bones), but it is an unreliable method of assessing cartilage or soft tissue damage.
- CT examination (CT) scan: A computer compiles multiple X-rays to create a 3D image of an area of the body. Non-contrast (without the use of dye) head CT to evaluate for the presence of intracerebral hemorrhage (intracranial hemorrhage).
- Magnetic Resonance Imaging (MRI): MRI uses a strong magnetic field and radio waves to create detailed images of internal structures and is used to assess joint swelling (hemoarthrosis), internal bleeding, or muscle bruising.
Many disorders that mimic bleeding events should be excluded before a diagnosis of hemophilia B is made. These include:
- Other clotting factor deficiencies: This includes hemophilia A (lack of factor VIII) and hemophilia C (lack of factor XI).
- von Willebrand factor (VWF) deficiency: VWF factor deficiency is the most common type of bleeding disorder. Insufficient or ineffective levels of VWF can cause prolonged bleeding because the body is unable to form platelet plugs (clots) after an injury. VWF deficiency differs from hemophilia B in several ways, including the presence of normal or increased clotting factors prothrombin time (PTT). Symptoms of von Willebrand disease are usually milder than those of true hemophilia.
- Platelet disorders: These can cause prolonged bleeding, such as immune Thrombocytopenia, thrombotic thrombocytopeniaand hemolytic uremic syndrome.
- disseminated intravascular coagulation (DIC): DIC is abnormal blood clotting due to a life-threatening condition such as septicemiaTrauma, Obstetric (Pregnancy) Complications, acute pancreatitisacute myeloid leukemia and adverse effects of blood transfusion.
- Vitamin K deficiency: This condition usually occurs in infancy.
- Scurvy or vitamin C deficiency: Deficiency of vitamin C can lead to poor wound healing and many other symptoms, including swollen gums and blood joints.
- Ehlers-Danlos Syndrome: This is a defect in collagen synthesis that results in fragile tissue, skin that is prone to stretching and chafing, and hypermobility of the joints (beyond the normal range).
- Fabry disease: This rare genetic disorder can cause spontaneous bleeding. Bleeding usually occurs in mucosal areas, such as the gums, and in people with hemophilia B it occurs in musculoskeletal areas.
- Child Abuse: Frequent bruising from physical abuse can be misidentified and confused with easy bruising from hemophilia. The inconsistent history of how trauma occurs, malnutrition, bloodshot eyes and wounds at different stages of healing increase the likelihood that child abuse is the cause of the bleeding. If suspected, physical abuse should be reported to the appropriate authorities for further investigation.
Hemophilia B can be suspected based on an individual’s symptoms, bleeding history, and family history. Normal blood work and coagulation tests do not rule out the diagnosis.
Usually, a specialized blood test for factor IX levels, called a factor IX test, must be done to confirm the diagnosis of hemophilia B and determine the severity of the condition. Genetic testing that can detect mutations in the F9 gene is also available.
A diagnosis of hemophilia B can be disconcerting at first, but it can be comforting to know the exact cause of a bleeding event. Knowing the cause means you can start addressing your symptoms.
Hemophilia B can affect your life by causing difficulty moving, unexpected bleeding, pain and uncertainty in everyday activities. Therefore, it is important to learn how to recognize the signs of bleeding and prepare for a bleeding event.
If you or your child does receive a hemophilia B diagnosis, be sure to find the nearest certified hemophilia treatment center (HTC). The experts there can help you develop the best treatment and management options so you can live with less fear.
It is also important to seek support from trusted family and friends who may be able to help when needed. Hemophilia can affect your mental health, so you may also find value in connecting with local, national and international support organizations.