Idiopathic Thrombocytopenia Purpura

Autoimmune disease resulting in destruction of platelets and presenting as bleeding disorders.

Idiopathic Thrombocytopenic Purpura; Werlhof Disease.

Acute: 6:100,000 per year in the general population. No sex predilection. Peak incidence occurs between 2 and 4 years of age. Chronic: 1:250,000 per year in the general population. Females affected two to three times more often than males. Peak incidence occurs between 20 and 50 years of age.

Not a genetic disorder. However, the development of antiplatelet antibodies in idiopathic thrombocytopenia purpura seems to be driven by an encounter with several platelet antigens through the clonal expansion of B cells using genetically restricted and highly specific combinations of heavyand light-chain gene products.

The majority of patients have circulating antiplatelet antibodies, directed at glycoproteins IIb and IIIa, leading to platelet destruction in the spleen and thrombocytopenia. Although platelet production is increased, it does not prevent thrombocytopenia.

Patients develop petechiae, bruising, and nosebleeds, usually after a viral illness. The remainder of the physical examination is normal. All laboratory tests are normal, with the exception of a markedly decreased platelet count and increased bleeding time. The platelet count is the only test needed to confirm the clinical diagnosis.

Petechiae, easy bruising, nosebleeds, thrombocytopenia. Typically course is benign with excellent prognosis. Treatment includes steroids, intravenous immunoglobulin, anti-D immunoglobin, chemotherapeutic agents, plasmapheresis, and splenectomy in refractory cases. Complications include intracranial hemorrhage (0.1-0.5%), usually with platelet counts below 20,000/mm3. Fetal thrombocytopenia is secondary to transplacental crossing of antiplatelet antibodies. There are two forms of idiopathic thrombocytopenia purpura:

• 1. Acute form is encountered in children ranging in age from 2 to 6 years, often after a viral illness. It usually has a sudden onset and disappears within a few weeks (less than 6 months).
• 2. Chronic form can occur at any age but is more common in women of childbearing age. It lasts more than 6 months (often several years) and requires continual follow-up care.

Consult hematologist regarding intravenous immunoglobulin and anti-D immunoglobulin. Check platelet count. Type and cross for platelets in emergency surgery (type and cross helps prevent alloimmunization in patients with frequent transfusions).

Bleeding usually does not occur with platelet counts greater than 50,000/mm3. The decision to transfuse platelets should be based on clinical bleeding, not actual platelet count. Central-neuraxial anesthesia is contraindicated because of the risk of hematoma. Some patients have undergone splenectomy, which makes them more prone to develop infection. Administration of perioperative corticosteroid supplementation is highly recommended.

Administration of pharmacological agents that affect platelet adhesion (e.g., aspirin) should be avoided. If anticoagulation is needed, extreme precautions are needed during administration (e.g., bleeding time, coagulation profile). Although some patients (e.g., children with the acute form) do not receive any treatment, most patients affected with this condition are given drugs that can affect the immune system, such as corticosteroids, infusion of immune globulin, vincristine, azathioprine, cyclophosphamide, or cyclosporine. These medications may lead to many interferences and complications both intraoperatively and postoperatively.

Disseminated Intravascular Coagulation: Acquired disorder in the context of shock.

Thrombotic Thrombocytopenic Purpura (TTP): Severe multisystem disorder of unknown etiology associated with pregnancy, diseases such as HIV, cancer, bacterial infection, and vasculitis, bone marrow transplantation, and drugs. Hemolytic uremic syndrome is the more common pediatric variant of this syndrome, with prominent renal involvement.