الفهرس 
Introduction
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Abstract
The human blood platelet is an interesting cell. It circulates as a disc known conventionally as the resting platelet. Platelets are the smallest of the three major types of blood cells, only about 20% of the diameter of red blood cells. The normal platelet count is 150,000-450,000 per microliter of blood, The typical shape of resting platelets is small disc-shaped cells, normally measuring 2 to 4 µm in diameter and 0.5 to 1.0 µm in thickness with a volume of about 6µl.
Platelets normally flow through the blood stream without sticking to each other, or any other cell. However, when platelets are stimulated by proteins and other chemicals that are released by tissue injuries, they aggregate together to form plugs that can fill breaks in blood vessels and stop bleeding.
Thrombasthenia is a platelet function disorder leads to defects in primary hemostasis which leads to bleeding symptoms such as;
• Bleeding during and after surgery
• Bleeding gums
• Easy bruising
• Nose bleeds (epistaxis)
• Prolonged bleeding with small injuries
• Heavy menstrual periods
a platelet function disorders may be congenital or acquired . congenital platelet disorders are generally recognized to increase the risks for excessive bleeding after significant haemostatic challenges(e.g. surgery, major dental procedures, trauma), and typically, the abnormal bleeding occurs with a rapid onset. The bleeding for congenital platelet disorders is influenced by the severity, and nature of the defect. A hereditary cause is suspected in patients with a lifelong history of easy bruising, petechiae, mucosal bleeding and excessive bleeding after tooth extractions or surgery.
Investigations for diagnosis of platelet function disorders are:
Complete blood count
Coagulation profile
Platelet function tests
Treatement of platelet function disorders :
The treatement of bleeding in individuals with platelet function disorders is focused on preventing bleeding with major and minor haemostatic challenges.
Local measures
Local measures are important in the management of bleeding in patients with thrombasthenia so as to avoid platelet transfusions. Proper dental hygiene from infancy is important to avoid invasive dental procedures later in life, and also to prevent gum disease, which will increase the risk of mouth bleeding. Proper compression of the nose/nasal bridge during epistaxis (and venipuncture sites) is the frontline in the management of these most frequent complications.
Desmopressin
Desmopressin is an analog of antidiuretic hormone (l-desamino-8-D-arginine vasopressin (DDAVP)) . that can shorten the bleeding time in patients with platelet function disorders, likely due to the stimulation of the release of endothelial cell VWF, which allows enhanced platelet adhesion to vessel walls.
Desmopressin can be given through intravenous,subcutaneous and intranasal routes.
For major procedures, desmopressin is most frequently administered intravenously by slow infusion, at a dosage of 0.3 µg (up to a maximum dose of 20 µg) given in 50 mL of 0.9% saline solution IV over 15 to 30 min, starting 1 h prior to the planned procedure, to ensure maximal response. It is preferable to give intravenous desmopressin while the patient is supine to avoid hypotension, and if hypotension occurs, the drug should be infused at a slower rate.
Subcutaneous injections are a convenient option for minor procedures, such as dental extractions or biopsies. Common side effects of desmopressin include facial flushing, temporary fluid retention, and in some individuals, mild headaches.
Antifibrinorlytic therapy
Use of fibrinolytic inhibitor drugs as aminocaproic acid or tranexamic acid in the setting of mucocutaneous bleeding, menorrhagia, or gastrointestinal bleeding has been reported in many patients with both inherited platelet dysfunction. Also used for preventing and controlling bleeding with dental extractions or oral/nasal surgery.
Recombinant factor VIla
The exact mechanism of how rVIIa improves haemostasis in platelet disorders is not fully understood but it is proposed that the increase in thrombin generated on the platelet surface as a result of direct activation of factors IX and X by rVIIa may result in faster platelet activation via this mechanism, compensating for either a lower number of platelets present or dysfunctional platelets.
rVIIa is produced by recombinant technology and not exposed to human blood products during its production. rVIIa is effective in preventing bleeding in planned surgical interventions but its efficacy in achieving haemostasis when bleeding established is variable.
Platelet transfusions
Platelet transfusions should be reserved for individuals with serious bleeding unresponsive to medical therapies or severe platelet function defects that cannot be managed by desmopressin therapy .
Prognosis
Treatment can usually control the bleeding. However, congenital platelet function defects are life-long conditions. There is no cure. Patients should take precautions to avoid bleeding.
Possible Complications
• Severe bleeding
• Iron deficiency anemia
• Intracranial haemorrhage
Prevention
A blood test can detect the gene responsible for the platelet defect.
Genetic counseling may be helpful to couples with a family history of a congenital platelet func