Acquired Hemorrhagic Disorders Chapter 29 describes how the application of clinical skills forms the cornerstone for the assessment of a potential bleeding disorder. After confirming that a bleeding disorder is present through a comprehensive medical history and physical examination, the…
Platelets play a critical role in hemostasis. When the vascular endothelium is disrupted, platelets adhere to the subendothelium and initiate primary hemostasis. The details of normal platelet physiology and function are presented in Chapter 26 . Excessive bleeding occurs if…
For many years, researchers suspected that hereditary coagulation defects underlie a large percentage of venous thromboembolic events that could not be attributed to identifiable acquired risk factors. Acquired risk factors for venous thrombosis consist of a heterogeneous group of conditions…
Rare bleeding disorders consist of inherited quantitative or functional deficiencies of factors I (fibrinogen), II, V, VII, X, XI, and XIII; combined factor deficiencies, particularly of factors V and VIII; inherited quantitative or functional deficiencies of vitamin K–dependent factors; and…
The clinical and laboratory features of the three most common hereditary bleeding disorders—hemophilia A (factor VIII deficiency), hemophilia B (factor IX deficiency), and von Willebrand disease (VWD)—are discussed in this chapter. Hemophilia A and hemophilia B are both caused by…
Platelets are small (1 to 4 µm in diameter) and were once thought to be fragments of other mature blood cells, dismissed as “blood dust.” They are now known to be highly specialized and organized structures released (by a still partly…
Introduction Before initiating the laboratory workup of any patient with a suspected defect of hemostasis, the hematologist must first verify that the patient has a clinical history, signs, and symptoms compatible with a bleeding disorder. This is not an easy…
Fibrinolysis is the process by which the insoluble protein fibrin is converted to a defined set of soluble degradation products. It occurs in both intravascular and extravascular locations and is essential to human health and survival. Modern molecular biologic techniques…
Overview of Coagulation Generation of the enzyme thrombin from its precursor prothrombin is the central event in the blood coagulation process, essential for hemostasis and the culprit in thrombosis. Blood loss through lack of hemorrhage control has captured the attention…
In an 1881 communication to the Turin Royal Academy of Medicine, the Italian physician Giulio Bizzozero disclosed the presence in circulating human blood of discrete elements that he termed “ piastrine ” (“ Blutplättchen ” in a 1882 publication in…