Thromb Haemostasis
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Haemostatic reference intervals are generally based on samples from non-pregnant women. Thus, they may not be relevant to pregnant women, a problem that may hinder accurate diagnosis and treatment of haemostatic disorders during pregnancy. In this study, we establish gestational age-specific reference intervals for coagulation tests during normal pregnancy. ⋯ However, levels of fibrinogen, D-dimer, and coagulation factors VII, VIII, and IX increased markedly. Protein S activity decreased substantially, while free protein S decreased slightly and total protein S was stable. Gestational age-specific reference values are essential for the accurate interpretation of a subset of haemostatic tests during pregnancy, delivery, and puerperium.
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Current strategies for diagnosing pulmonary embolism (PE) include a clinical decision rule (CDR), followed by a D-dimer assay in patients with an unlikely clinical probability. We assessed the implementation of the current guidelines for the diagnosis of PE. A first questionnaire was sent to internists and pulmonologists to assess the proportion of physicians that adequately applied the guidelines. ⋯ Our findings indicate that physicians do not use the guidelines for diagnosis of PE consistently. Furthermore, the knowledge of an abnormal D-dimer test result before seeing the patient leads to a higher CDR score. Physicians should therefore first examine patients before taking note of the D-dimer test result.
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Severe aortic stenosis is associated with a haemostatic abnormality that resembles acquired von Willebrand syndrome type 2. It is assumed that high shear conditions render large von Willebrand factor (VWF) multimers accessible to cleavage by ADAMTS-13. However, whether loss of these large multimers affects platelet function by impairing adhesion, aggregate formation, or both has not been evaluated in clinical studies. ⋯ Both adhesion (p=0.03) and ADP-inducible platelet aggregation (p=0.002) improved considerably after valve replacement. Consequently, ADP-inducible expression of P-selectin was higher after valve replacement (p=0.001). We conclude that reduced levels of large VWF multimers associated with aortic stenosis lead to impairment of both adhesion and, especially, ADP-inducible platelet aggregation.
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Patients subjected to haemodilution during surgery are at increased risk of bleeding. We hypothesised that, in the acquired dilutional coagulopathy, insufficient haemostasis is due to either insufficient thrombin generation or insufficient fibrin clot formation. In tissue factor-activated plasmas from patients with coagulation deficiency, we measured time curves of thrombin generation and fibrin clot formation (thromboelastography). ⋯ In plasmas from patients undergoing major surgery, factor levels were 38-41% of normal, and these levels increased after plasma transfusion. Taking preset thresholds for normal thrombin generation and fibrin clot formation, at least one of these processes was low in 88-93% of the patients with (persistent) bleeding, but only in 40-53% of the patients without bleeding. In conclusion, the ability of thrombin generation and fibrin clot formation is independently reduced in acquired dilutional coagulopathy, while minimal levels of both are required for adequate haemostasis.
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Evaluation of clot formation in neonates is troublesome. Our aim was to investigate cord blood clot formation of pre-term versus full-term infants and adults, using rotating thromboelastogram (ROTEM), Pentafarm, Munich, Germany). ROTEM was investigated in cord blood of 184 full-term and 47 pre-term infants. ⋯ This is the first study assessing clot formation by ROTEM in pre-term infants. Clot formation parameters of term and premature infants correlated with gestational age. The predictive value of clot formation tests in neonates deserves further attention.