A bleeding disorder is a flaw in the body's blood clotting system (also called coagulation). The process of clotting to stop bleeding depends on the interactions of a number of blood proteins, known as clotting factors. A bleeding disorder occurs when one of these clotting factors is missing or does not work properly.

A number of usually inherited bleeding problems are followed at the UC Davis HTC:


Classic hemophilia (Hemophilia A and B) primarily affects males and is hereditary, transmitted from one generation to another. Women carry the genetic trait for classic hemophilia, and may be symptomatic carriers, (see "Special Bleeding Problems for Women", page 14-15) About one in 5,000 males will be born with hemophilia. Individuals with hemophilia have excessive bleeding after injuries or spontaneous bleeding episodes because of the lack of a specific coagulation factor in their blood.
The most well-known bleeding disorder is Hemophilia A, caused by a lack of the coagulation factor VIII (approximately 80 percent of hemophilia cases). Hemophilia B (also known as Christmas disease) is caused by the lack of the coagulation factor IX (20 percent of hemophilia cases). Both factor VIII and IX deficiencies occur in mild, moderate and severe forms depending on the level of the missing coagulation factor. The normal range for factor VIII is 50 percent to 150 percent.
Mild -- 6 percent to 49 percent  ----- excessive bleeding after surgery, dental work, or trauma
Moderate -- 2 percent to 5 percent ----- excessive bleeding after surgery, dental work, trauma, and rarely spontaneous bleeding
Severe  -- Less than 1 percent ----- bleeding spontaneously, joint injury, intracranial and internal bleeding

von Willebrand Disease

Although less widely known than hemophilia, von Willebrand disease (vWD) is actually the most common inherited bleeding disorder and may affect men or women. It is estimated that from 1 percent to 3 percent of the general population have abnormalities in the clotting protein called von Willebrand factor (vWF), with clinical symptoms that may be very mild, moderate or severe. Von Willebrand disease differs from hemophilia in that it is not linked to gender; males and females are equally affected. An affected parent has a 50 percent chance of passing the affected gene on to each child (see chart).
Not everyone with vWF mutations displays visible symptoms. Typical symptoms experienced by patients with von Willebrand factor defects include:

  • nosebleeds
  • easy bruising
  • heavy menstrual flow
  • unusual bleeding from the mouth or gums
  • unexplained bleeding after surgery or trauma

Sometimes bleeding is caused by injury, while other times there are no obvious causes. Gastrointestinal or urinary tract bleeding also may occur in patients with vWD. In severely affected individuals joint or muscle bleeding is also possible.
Different types of von Willebrand disease:

  • Type 1 is the most common form of vWD (about 80 percent of all cases) and is characterized by reduced levels of vWF. Bleeding symptoms tend to be mild.
  • People with Type II usually have bleeding symptoms of mild to moderate severity. Type II is usually due to a defective vWF protein.
  • People with Type III have total or near total absence of vWF. Their bleeding symptoms are often severe and can be confused with hemophilia.

Other Inherited Bleeding Disorders

A defect in the function of any other clotting factors may cause bleeding, and the severity may range from mild to severe depending on the mutation or particular defect. While these disorders occur less often than Hemophilia A or B, patients with other bleeding disorders and their families can still benefit from the comprehensive service of our HTC.


Many of our patients have been referred to the HTC for diagnostic evaluation due to severe or unusual symptoms. These symptoms can include unexplained bruising, soft tissue bleeding, mouth and nosebleeds, heavy menstrual periods, or unexplained excessive bleeding following surgery. Some families of previously undiagnosed patients have been accused of child abuse until the underlying bleeding disorder causing the excessive bruising/bleeding has been identified.

What are the Potential Complications of Bleeding Disorders?

Life Threatening Bleeds

The five major sites of serious bleeding are:

  • Intracranial or spinal cord
  • Throat
  • Intra-abdominal areas
  • Limb compartments, such as thigh, calf, forearm, or upper arm
  • Eye

All of these bleeding episodes are characterized by:

  • bleeding into an enclosed space
  • compression of vital tissue; and
  • potential loss of life, limb or function.

Serious bleeding requires immediate assessment and intervention. Patients with severe or moderate hemophilia are at greater risk for spontaneous serious bleeding. Trained intervention, communication, reassurance, and support are essential elements in helping patients and families through these crises. These bleeding episodes often cause great anxiety and fear of the outcome in patients and their families. The uncommon nature of bleeding disorders, and especially these life-threatening bleeding episodes, only re-emphasizes the importance of involving the HTC staff in each episode. Statistics from the Centers for Disease Control and Prevention show that patients with bleeding disorders not treated or followed at hemophilia treatment centers suffer a 60 percent increase in mortality rates.

Joint Damage

A frequent complication of hemophilia is joint damage or hemophilia arthropathy, which is the result of repeated bleeding into joints. The most commonly affected joints are the knees, elbows and ankles. Joint bleeding in patients with bleeding disorders leads to both chronic and acute pain as well as joint degeneration, swelling and loss of range of motion. Joint and muscle bleeding are less common among people with von Willebrand disease and mild hemophilia. For those who suffer from arthropathy, there are several options with medication and physical therapy to reduce pain and preserve joint function. The HTC also stresses the importance of engaging in routine exercise to reduce or eliminate joint damage by strengthening joints and muscles. For those with severe arthropathy, surgical options are available, including total joint replacement by orthopedists who have extensive experience with hemophilia.

Menstrual flows often lead to low iron levels

Therefore, it is recommended that women with bleeding disorders routinely be tested for anemia. To help control menstrual bleeding, HTC doctors may prescribe birth control pills or Stimate nasal spray which both boost factor VIII and von Willebrand factor levels. In addition, the HTC can provide expert counseling, including genetic counseling about the disorder and family planning issues.

Finally it is critical that a pregnant woman with a bleeding disorder be followed closely by an a hemophilia treatment center

The HTC staff can assist an obstetrician in providing both the pre-and postnatal care for the woman and her fetus and recommend appropriate testing and care for a baby with a possible bleeding disorder.