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|Advanced Training Course Atlanta Abstract Preview|
Featuring the latest research to address the challenges clinicians face in platelet disorders, bleeding disorders and venous thrombosis, this course is certain to advance your learning and your career. Content is selected for both early career professionals as well as more advanced learners seeking an update. Click here for the full program. Register here.
To give you a better idea of what to expect, read the free preview of Course Chairman Nigel Key's abstract, "How to Approach a Patient with Bleeding" below:
How to Approach a Patient with Bleeding
Nigel S. Key
A common cause of referral to the expert in hemostasis is the evaluation of a patient with a possible bleeding disorder. Patients with milder non-thrombocytopenic bleeding disorders, frequently perceived or proven to be inherited, are seen on a regular basis both in pediatric and in adult practice, where they present a significant diagnostic challenge. In this session, a structured approach to these patients will be discussed.
The evaluation begins with a careful history. These patients most often present with complaints of muco-cutaneous bleeding suggestive of a primary hemostatic disorder; bleeding may be spontaneous and/or post-traumatic or post-surgical. Bleeding sites that tend to have a higher discriminative value include menorrhagia, post-surgical or post-dental extraction bleeding, and post-partum hemorrhage1,2. On the other hand, easy bruising is generally associated with a much lower discriminative power, especially when it occurs in women. However, because previous surveys have shown that up to 20% of the control population may report a history of abnormal bleeding in one or more of these sites, the differentiation between a ‘normal’ and ‘abnormal’ bleeding history is still challenging. Earlier onset and a positive family history are important clues to a possible inherited disorder. Since aspirin may reveal the presence of abnormal bleeding in an otherwise compensated mild disorder, it is important to take a careful medication history of this and other anti-platelet agents. Over the previous decade, bleeding assessment tools (BATs) that systematically score each bleeding symptom have become incorporated into clinical practice. It is important to be aware that several iterations of BATs have been used in various studies, since their first appearance in the literature in 2005. However, the ISTH-BAT was proposed in 20103, and is currently recommended for the initial workup of bleeding disorders. It is intended for use in both children and adults, and addresses 14 distinct bleeding symptoms. Normal ranges have been established for children, as well as adult males and females4.
Laboratory investigation should include the usual plasma screening tests of hemostasis, including the PT and aPTT. Most frequently however, these are normal. Some labs routinely screen for deficiencies of PAI-1, factor XIII, or a2-antiplasmin. However, because of the extreme rarity of these disorders, we reserve screening for selected cases. In contrast, two of the major categories that are relatively common in this patient group are von Willebrand disease and platelet function defects (PFDs). Thus, in most patients, a screen for both VWD and PFDs is indicated. There is a common misconception that the PFA-100 screening assay is sensitive to both of these categories, but that is far from the truth. In fact, milder variants of VWD will be missed, and the assay is not at all sensitive (≈30%) to the ‘common or garden’ mild intrinsic platelet defects. Therefore, directed screening for both VWD and PFDs is necessary. The diagnosis of VWD will be discussed separately in this symposium. The diagnosis of PFDs requires light transmission aggregometry (LTA), evaluating the response of patient platelets – either in platelet rich plasma or in whole blood – to a panel of agonists. Despite being in clinical practice for >50 years, LTA was only recently subjected to standardization exercises and an attempt to reach consensus on universally accepted diagnostic criteria. In addition, LTA has been modified to include simultaneous measurement of ATP secretion, usually by the technique of lumi-aggregometry. Assessment of platelet secretion should be a routine part of the evaluation, since some patients with secretion defects due to storage pool deficiency do not manifest any abnormality of LTA. In many centers, it is also routine to perform whole mount electron microscopy on isolated platelets, as this can be a very convenient and reliable way to screen for delta storage pool deficiency.
Taking the historical and laboratory screens together, Quiroga and colleagues prospectively evaluated 280 sequential patients with pathologic mucocutaneous bleeding referred to their center. ‘Firm’ diagnoses were reached in the following proportions: VWD in 18%, PFDs in 23%, and 4% with milder clotting factor deficiencies5. However, >50% were labeled as ‘bleeding of unknown cause (BUC). These figures are very similar to several other large series, although the relative proportions of VWD and PFDs may vary somewhat among different ethnic groups, even within the same country. It seems likely that patients with significant bleeding histories but without a definitive cause (i.e. in the previously mentioned ‘BUC’ category) represent a heterogenous group with multiple possible etiologies. They illustrate the inadequacy of the testing that can be routinely applied in most clinics, as well as a lack of knowledge of the underlying pathophysiology. As such, it is inappropriate to assume that a lack of a firm laboratory diagnosis implies that the patient does not a bleeding disorder. More information is also needed to understand the longer-term outcomes in these patients when they return to their communities.
1. Quiroga T, Mezzano D. Is my patient a bleeder? A diagnostic framework for mild bleeding disorders. Hematology 2012 (American Society of Hematology Educational Program) 466-474
2. Boender J, Kruip MJ, Leebeek FW. A diagnostic approach to mild bleeding disorders. J Thromb Haemost 2016:14;1-10
3. Rodeghiero F, Tosetto A, Abshire T, et al, on behalf of the ISTH/SSC Joint VWF and Perinatal/Pediatric Hemostasis Subcommittees Working Group. ISTH/SSC bleeding assessment tool: a standardized questionnaire and a proposal for a new bleeding score for inherited bleeding disorders. J Thromb Haemost 2010:8;2063-2065
4. Elbatarny M, Mollah S, Grabell J, et al. Normal range of bleeding scores for the ISTH-BAT: adult and pediatric data from the merging project. Haemophilia 2014:20;831-835
5. Quiroga T, Goycoolea M, Panes O, et al. High prevalence of bleeders of unknown cause among patients with inherited mucocutaneous bleeding. Haematologica 2007:92(3);357-365
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