Evaluation of a patient for a bleeding tendency or excessive hemorrhage is common in clinical medicine. It requires identification of key elements in the patient's history and physical examination and integration of these data with laboratory measurements and therapeutic maneuvers. Often the evaluation is part of the diagnosis and management of another illness as, for example, the patient who bleeds excessively during or after surgery or who develops a coagulopathy as part of a systemic illness. Therefore, successful diagnosis of a bleeding disorder very much depends on the skills of the clinician at the bedside.
Important diagnostic information is provided by the clinical setting because of the clear associations between bleeding abnormalities and certain disease states. To uncover these relationships, the clinician needs to collect the following data:
Who: The patient's age, sex, racial background, and family history of abnormal bleeding all are important.
When: Any association with a disease state, trauma, surgery, or drug ingestion should be identified. In addition, details of the time of onset and course of the bleeding event are important.
Where: The site or sites of bleeding, whether skin, mucous membranes, gastrointestinal (GI) tract, solid organ, joint, or muscle, need to be identified.
What: The physical characteristics of the bleeding, especially the distinction between petechial (capillary) hemorrhage and the purpura, ecchymoses, and hematoma formation seen with larger vessel bleeding, need to be described.
Based on these data, it is often possible to target the nature of the bleeding disorder. Patients who have a hematologic malignancy or are undergoing high-dose chemotherapy are at risk for severe thrombocytopenia and mucosal bleeding. Platelet dysfunction can also cause mucosal bleeding, as seen in patients with acquired von Willebrand disease (vWD) or essential thrombocythemia. In contrast, patients receiving warfarin can be expected to show an abnormality in the production of the vitamin K–dependent coagulation factors. Liver disease patients are at risk for developing a multifactor deficiency state and, at times, a defect in fibrinogen structure and function. Finally, patients with severe sepsis can develop a consumptive coagulopathy affecting all coagulation factors.
As for the detection of a congenital coagulopathy, the absence of any complicating illness or anticoagulant drug exposure obviously directs the clinician's attention to the possibility of an inherited defect. In this situation, the patient's age, sex, race, family history, and the characteristics of the onset and course of the bleeding can be major clues to the diagnosis.
Several laboratory tests are available to evaluate the coagulation pathways. Some of these tests, such as platelet function, require the expertise of a consultant hematologist and a reference laboratory. Others are available through the routine laboratory. It is the routine tests that every clinician should be able to use in evaluating a coagulation defect (Table 29-1). These tests include the platelet count, ...