Hemophilia
A hereditary bleeding disorder, hemophilia results from deficiency of specific clotting factors. More than 80% of all patients with hemophilia have hemophilia A (classic hemophilia), which results from deficiency of factor VIII. Hemophilia B (Christmas disease) accounts for 15% of patients with hemophilia; it results from a deficiency of factor IX. However, other evidence suggests that hemophilia may actually result from nonfunctioning factors VIII and IX, rather than from their deficiency. Hemophilia is the most common X-linked genetic disease, occurring in about 1.25 per 10,000 live male births.
The severity and prognosis of bleeding disorders vary with the degree of deficiency and the site of bleeding. The overall prognosis is best in mild hemophilia, which doesn’t cause spontaneous bleeding or joint deformities. Advances in treatment have greatly improved the prognosis, and many patients with hemophilia live normal life spans.
Causes
Hemophilia A and B are inherited as X–linked recessive traits. Female carriers have a 50% chance of transmitting the gene to each daughter, who would then be a carrier, and a 50% chance of transmitting the gene to each son, who would be born with hemophilia.
Hemophilia produces abnormal bleeding, which may be mild, moderate, or severe, depending on the degree of factor deficiency. After a platelet plug forms at a bleeding site, lack of clotting factors impairs the formation of a stable fibrin clot. Immediate hemorrhage isn’t prevalent, but delayed bleeding is common.
Complications
Bleeding into joints and muscles causes pain, swelling, extreme tenderness and, possibly, permanent deformity. Bleeding near peripheral nerves may cause peripheral neuropathies, pain, paresthesia, and muscle atrophy. If bleeding impairs blood flow through a major vessel, it can cause ischemia and gangrene. Pharyngeal, lingual, intracardial, intracerebral, and intracranial bleeding may all lead to shock and death.
Assessment
Varying assessment findings depend on the severity of the patient’s condition. A patient with undiagnosed hemophilia typically presents with pain and swelling in a weight-bearing joint, such as the hip, knee, and ankle.
Mild hemophilia commonly goes undiagnosed until adulthood because the patient with a mild deficiency doesn’t bleed spontaneously or after minor trauma but has prolonged bleeding if challenged by major trauma or surgery. Postoperative bleeding continues as a slow ooze or ceases and starts again, up to 8 days after surgery.
Moderate hemophilia causes symptoms similar to those of severe hemophilia but produces only occasional spontaneous bleeding episodes. Severe hemophilia causes spontaneous bleeding.
Pediatric pointerCommonly, the first sign of severe hemophilia is excessive bleeding after circumcision. Later, spontaneous bleeding or severe bleeding after minor trauma may produce large subcutaneous and deep intramuscular hematomas.
The patient’s history may reveal prolonged bleeding after surgery (including dental extractions) or trauma, or joint pain if episodes of spontaneous bleeding into muscles or joints have occurred. The history may disclose signs of internal bleeding, such as abdominal, chest, or flank pain, episodes of hematuria or hematemesis, and tarry stools. It should also reveal any activity or movement limitations that the patient has experienced in the past and any need for assistive devices, such as splints, canes, or crutches.
Inspection may reveal hematomas on the extremities or the torso or both and, if bleeding has occurred in joints, joint swelling. Joint range of motion (ROM) may be limited, and the patient may complain of pain when this assessment is done if bleeding has occurred into the joints.
Diagnostic tests
Specific coagulation factor assays can aid in the diagnosis of the type and severity of hemophilia. A positive family history can also support the diagnosis of hemophilia.
Characteristic findings in hemophilia A are:
factor VIII assay 0% to 25% of normal prolonged activated partial thromboplastin time (APTT)
normal platelet count and function, bleeding time, and prothrombin time.
Characteristic findings in hemophilia B are:
deficient factor IX assay
baseline coagulation results similar to those of hemophilia A, with normal factor VIII.
In hemophilia A or B, the degree of factor deficiency determines severity:
mild hemophilia—factor levels 5% to 25% of normal
moderate hemophilia—factor levels 1% to 5% of normal
severe hemophilia—factor levels less than 1% of normal.
Blood studies are the key diagnostic tool for assessing hemophilia, but additional tests may be ordered periodically to evaluate complications caused by bleeding. For example, a computed tomography scan would be used for suspected intracranial bleeding, arthroscopy or arthrography for certain joint problems, and endoscopy for GI bleeding.
Treatment
Hemophilia is incurable, but treatment can prevent crippling deformities and prolong life. Correct treatment quickly stops bleeding by increasing plasma levels of deficient clotting factors to help prevent disabling deformities that result from repeated bleeding into muscles, joints, and organs.
In hemophilia A, cryoprecipitated antihemophilic factor (AHF), lyophilized AHF, or both, given in doses large enough to raise clotting factor levels above 25% of normal, can permit normal hemostasis. (See Treating hemophilia A.) Before surgery, AHF is administered to raise clotting factors to hemostatic levels. Levels are then kept within a normal range until the wound has healed. Fresh frozen plasma can also be given, but it does have some drawbacks. (See Reviewing factor replacement products, page 374.)
Inhibitors to factor VIII develop after multiple transfusions in 10% to 20% of patients with severe hemophilia. This renders the patient resistant to factor VIII infusions. Desmopressin may be given to stimulate the release of stored factor VIII, raising the level in the blood.
In hemophilia B, administration of factor IX concentrate during bleeding episodes increases factor IX levels. Other treatments (recently approved) include the use of NovoSeven, administered I.V., which acts directly on a damaged vessel to stop bleeding and promote clotting at the injury site.
A patient with hemophilia who undergoes surgery needs careful management by a hematologist with expertise in hemophilia care. The patient will require deficient factor replacement before and after surgery. Such replacement may be necessary even for minor surgery such as a dental extraction. In addition, aminocaproic acid is commonly used for oral bleeding to inhibit the active fibrinolytic system present in the oral mucosa.
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