Von Willebrands Disease

Also known as angiohemophilia, pseudohemophilia, or vascular hemophilia, von Willebrand's disease is a hereditary bleeding disorder characterized by prolonged bleeding time, moderate deficiency of clotting factor VIII (antihemophilic factor [AHF]), and impaired platelet function.

Von Willebrand's disease commonly causes bleeding from the skin or mucosal surfaces and, in females, excessive uterine bleeding. Bleeding may range from mild and asymptomatic to severe hemorrhage. The prognosis is usually good because most cases are mild. Severe forms may cause hemorrhage after laceration or surgery as well as GI bleeding. Excessive postpartum bleeding is uncommon because factor VIII levels and bleeding time abnormalities become less pronounced during pregnancy. Massive soft-tissue hemorrhage and bleeding into joints seldom occur. Bleeding episodes occur sporadically; a patient may bleed excessively after one dental extraction but not after another. The severity of bleeding may lessen with age.

Causes

Von Willebrand disease is almost always inherited. This means that parents pass a gene for the disease on to their children. The gene for the disease is usually dominant . That means that a parent with the disease has a 50 percent or 1 in 2 chance of passing the gene to each of his or her children. Type 1 and Type 2 von Willebrand disease are usually inherited this way.

The gene for Type 3 von Willebrand disease is usually recessive . That means the child would have to inherit the gene from both parents. Even if both parents have mild or no symptoms, the child can have severe symptoms.

In rare cases, von Willebrand disease can be acquired (developed later in life).

Signs and Symptoms

The symptoms of von Willebrand disease may include:

• bruising that's unusual in location or frequency
• abnormal menstrual bleeding
• bleeding in the mucous membranes, such as the gums, nose, and lining of the gastrointestinal system
• excessive or prolonged bleeding after a tooth is pulled or tonsils are removed or prolonged oozing from cuts

Diagnostic tests

• Normal platelet count
• Prolonged bleeding time
• Reduced von Willebrand factor level
• Reduced platelet aggregation ( platelet aggregation test )
• Ristocetin co-factor is reduced

This disease may also alter the results of the following tests:

• Factor VIII level
• Von Willebrand factor multimers

Treatment

The objectives of treatment are to shorten bleeding time by local measures and to replace factor VIII (and, consequently, factor VIIIvwf) by infusion of cryoprecipitate or blood fractions that are rich in factor VIII.

In many cases, the disorder is so mild that unless surgical or dental procedures are needed, no treatment may be required other than having the patient avoid taking aspirin. However, preparation is necessary for these procedures even for patients with mild forms of the disease.

During bleeding episodes and before even minor surgery, I.V. infusion of cryoprecipitate or fresh plasma (in quantities sufficient to raise factor VIII levels to 50% of normal) shortens bleeding time. Desmopressin may be effective in mild disease because it enhances cellular release of stored factor VIII.

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