There are many unique issues that may make a pathologist's consultation helpful in hemostasis testing. Besides the rapidly expanding knowledge of both bleeding and thrombotic disorders and a wide test menu, hemostasis testing is very sensitive to preanalytical issues (hemolysis, fill volume, time, temperature, storage conditions) and the interference of many commonly prescribed drugs. The pathologist can serve an important role in the evaluation of a patient for a bleeding or thrombotic disorder. Using defined algorithms, hemostasis testing can proceed in a logical fashion and be reported using patient-specific comments that take into account clinical history and medication therapy. This approach can improve the diagnostic process, preventing misdiagnoses and leading to a decreased time to diagnosis and an improved utilization of laboratory resources.
An Algorithmic Approach To Hemostasis Testing Free
An Algorithmic Approach to Hemostasis Testing is an up-to-date, well-illustrated reference text and practical guide for pathologists and laboratories engaged in hemostasis testing. It includes sections on hemostasis physiology, the basics of laboratory testing and interpretation, specimen collection and processing, patient history and diagnostic criteria, and anticoagulant drug monitoring. Recommendations for thrombophilia testing in adults, women, and children also are presented. Each chapter contains a thorough list of recommended reading, and examples of both adult and pediatric reference ranges are included. The second edition contains new chapters on quality, emergency assessment of bleeding patients, consultation in hemostasis testing, and antifibrinolytic and thrombolytic agents. Case studies and detailed algorithms related to bleeding disorders and venous thrombophilic disorders are presented, including elevated PT and/or aPTT, bleeding with normal PT and aPTT, abnormal thrombin time, fibrinolytic and platelet disorders, von Willebrand disease, heparin-induced thrombocytopenia, and antiphospholipid antibody syndrome and lupus anticoagulants.
Yes, to produce valid results for hemostasis/thrombosis testing, including factor assays, specimen integrity is crucial and must be maintained. For additional guidance, please refer to the Hemostasis/Thrombosis Specimen Collection and Handling instructions.
Patients with elevated platelet counts may have clinical bleeding, but may also be asymptomatic or have thrombosis. In these patients, laboratory evaluation should be primarily aimed at elucidating the cause of the thrombocytosis and should include a complete blood cell count, peripheral blood smear, bone marrow evaluation, cytogenetic study, and platelet aggregation study. In general, platelet function screening tests have little usefulness in evaluating these disorders and do not necessarily correlate with further platelet function tests. In patients with thrombocytosis, the differential diagnosis is primarily between a reactive thrombocytosis and a myeloproliferative process (essential thrombocytosis, chronic myelogenous leukemia, polycythemia vera, and myelofibrosis). The algorithmic approach to the diagnosis of thrombocytosis is shown in Figure 2. In general, patients with a myeloproliferative disorder often have platelet counts greater than 1 106/μL, and patients with reactive thrombocytoses have counts less than this, but there is a great deal of overlap. For myeloproliferative disorders, characteristic features of a specific disease can be discerned by examination of the peripheral blood smear, bone marrow, and cytogenetic studies.
Disorders in which the platelet count is decreased can be divided, for evaluation purposes, by the size of the platelets. Thrombocytopenias can be congenital or acquired, but they have been grouped by platelet size in this discussion. See Figure 3 for an algorithmic approach to small and large platelets and Figure 5 for an approach to the diagnosis of normal-sized platelets.
Several macrothrombocytopenia disorders are characterized by the presence of neutrophilic inclusions. May-Hegglin anomaly is the most common macrothrombocytopenia and is an autosomal dominant disorder characterized by Dohle body inclusions in neutrophils with a mild bleeding disorder.17,90 The Dohle bodies are blue, spindle-shaped inclusions in the periphery of the neutrophil cytoplasm (Figure 4). The thrombocytopenia is usually moderate, with platelet counts of 60 to 100 103/μL, and the mean MPV is approximately 12.5 fL, but is often much larger. Laboratory studies will usually show normal platelet aggregation and a normal bleeding time,91 attesting to the increased functionality of the larger platelets. Electron microscopic analysis of platelets in the May-Hegglin anomaly will often show a disorganization of the microtubules.17,91 Electron microscopic analysis of the neutrophilic inclusions shows them to lack a limiting membrane, be free of specific granules, and contain parallel bundles of ribosomes, microfilaments, and segments of endoplasmic reticulum.17 Platelet surface glycoproteins are usually normal.92
Moll et al. suggest the "4P" approach, which is patient selection, pretest counseling, proper laboratory test interpretation, and provision of education and advice. Additionally, they created a risk of recurrence triangle to decide based on risk assessment, how long it would take to achieve anticoagulation. Not every patient requires testing for thrombophilia. Testing is not advisable during the acute thrombotic event (rather schedule for 3-month follow-up) while being on anticoagulation, and patients with provoked thromboembolism.[63][64] In cases of unprovoked thromboembolism, guidelines differ, and some suggest starting anticoagulation balancing risks and benefit without specific thrombophilia testing. Testing might be useful to exclude thrombophilia and stop anticoagulation. Testing to guide primary prevention in relatives of asymptomatic VTE patients is not useful. Nevertheless, anticoagulation as primary prevention during exposure to provoking factors merits consideration. Testing should be a two-staged approach or 3 months after finishing anticoagulation.[65][66] Testing guidelines differ between medical societies.[67][68] Some authors propose thrombophilia testing in patients with unprovoked or recurrent VTE, VTE in young patients (less than 40 years old), in patients with strong family history, thrombosis in unusual sites (cerebral, mesenteric, hepatic, renal), neonatal purpura fulminans, warfarin-induced skin necrosis, and fetal loss.[19][11][20]
Noninvasive prenatal diagnosis using quantitative digital polymerase chain reaction testing of free fetal DNA in the maternal circulation has been reported. However, this technique remains a research tool. [29]
As a planned intervention, in association with endoscopic control: The addition of prophylactic embolization in addition to endoscopic hemostasis has been investigated by several authors, including most recently with two randomized controlled trials [143, 144]. Laursen et al. demonstrated a trend toward improved outcomes in patients who underwent additional prophylactic embolization. However, the second RCT by Lau et al. failed to confirm this observation. This approach was also supported by a retrospective series by Mille et al. [145].
The FAST examination has developed into a key instrument in the acute evaluation of trauma patients with suspected abdominal and thoraco-abdominal injuries [153]. FAST techniques are being used with reduced examination times and a focused assessment of specific clinical issues using only a few standardised cross-sectional planes [154]. As a rapid and non-invasive diagnostic approach to the detection of haemorrhages in the peritoneal, pleural and pericardial cavities in the emergency department, FAST represents a cornerstone of the primary ATLS survey [153, 155,156,157]. Volume status can be assessed non-invasively using ultrasound of the inferior vena cava. Several studies have indicated the specificity and accuracy, but low sensitivity, of initial FAST for detecting and excluding free intraperitoneal fluid as well as intra-abdominal injuries [158,159,160,161,162,163,164] in both penetrating [165] and blunt abdominal trauma [166, 167]. Liu and colleagues [168] found a high sensitivity, specificity and accuracy of initial ultrasound examination for the detection of haemoperitoneum. In a retrospective registry study, free fluid or organ injury was detected in 72.4% of patients using FAST versus 84.3% using CT, yielding a sensitivity of 92% for initial FAST [169]. In another retrospective study that included 1540 hypotensive patients (1227 blunt, 313 penetrating trauma), ultrasound examination had a sensitivity and specificity close to 100% for free intra-abdominal fluid [170]. The double-line sign, which has been described as a wedge-shaped hypoechoic area in the Morison pouch, bounded on both sides by echogenic lines during FAST, may represent a false-positive finding for free intraperitoneal fluid with an overall prevalence of 27% [171].
Our NGS panels are custom-built and designed to include every clinically relevant part of each gene expertly selected for inclusion. Supplemental Sanger sequencing is included in our panel design to optimize reliable and accurate detection of relevant variants. This approach to panel design maximizes diagnostic utility and minimizes the risk of off-target results or incidental findings more likely to be identified by a broader testing platform designed for a less specific purpose.
Type II is extremely rare and is not considered a risk factor for thrombophilia. While functional protein S activity is commonly measured to detectprotein S deficiency, there are problems with this test. It is a clot-based assay and has a large coefficient of variation; the test is affected by patientswho have factor V Leiden mutation or lupus anticoagulant. On the contrary, free protein S antigen assay is more specific for detecting true deficienciesand only free protein S has anticoagulant activity. Measuring free protein S antigen provides more reliable results, when testing for protein S deficiencyis clinically warranted. 2ff7e9595c
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