Approaches to investigating common bleeding disorders: An evaluation of North American coagulation laboratory practices

Abstract

Bleeding disorders commonly result from deficiencies or defects in von Willebrand factor (VWF), platelets, coagulation factors, or fibrinolytic proteins. The primary goal of our study was to assess current North American coagulation laboratory practices for diagnosing bleeding disorders, using an on‐line patterns‐of‐practice survey of diagnostic laboratory members of the North American Specialized Coagulation Laboratory Association. The survey examined laboratory approaches to evaluating bleeding disorders, with specific questions about the tests and test panels offered and compliance to recent guideline recommendations on diagnosing von Willebrand disease (VWD) and platelet function disorders. All laboratories responding to the survey performed a prothrombin time/international normalized ratio, an activated partial thromboplastin time, and coagulation factor assays, and many tested for VWD and platelet disorders. However, few laboratories had test panels that evaluated the more common bleeding disorders and few performed some assays, including VWF multimer assessments and assays for fibrinolytic disorders. Additionally, the cutoffs used by laboratories to diagnose type 1 VWD varied considerably, with only a minority following the National Heart Lung Blood Institute recommendations. In contrast, laboratories that tested for platelet function disorders mostly complied with aggregation testing recommendations, as published in the recent North American guidelines. Our results indicate that there are some gaps in the strategies used by laboratories to diagnose bleeding disorders that might be addressed by development of further guidelines and test algorithms that emphasize evaluations for common bleeding disorders. Laboratories may also benefit from guidelines on test interpretation, and external evaluation of their bleeding disorder testing strategies. Am. J. Hematol. 2012. © 2012 Wiley Periodicals, Inc.

A cartridge based sensor array platform for multiple coagulation measurements from plasma

“…Thus, fast, reliable and simple assays are needed to monitor the coagulation parameters 5,6 . Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are the most frequently performed tests to determine the functionality of the blood coagulation system 7 . The measurement of PT and aPTT depends on activation by the tissue factor (extrinsic system) or surface (intrinsic system), respectively.…”

Intracerebral Bleeding in Young Infants due to Rare Etiologies–A Report of two Cases

“…Mucosal bleeding, petichiae and easy bruisability may be seen due to platelet disorders or disorders of vessel wall integrity, while intra-articular bleeding, hematomas or intracerebral bleeding reflects possibility of clotting factor deficiency. The investigation of bleeding disorder is a step by step process which includes a complete blood count, peripheral blood smear, PT, APTT, coagulation factors assay, d-dimer, factor inhibitors, fibrinogen, platelet function and aggregation study, Risocetin factor, thrombin time and von Willibrand factor [4]. Our first patient was diagnosed as a congenital factor V deficiency.…”

Coagulation measurement from whole blood using vibrating optical fiber in a disposable cartridge

“…Blood coagulation times are usually measured with either PT or activated partial thromboplastin time (aPTT) test protocols. 32 The average PT test time is around 13 s while the average aPTT test time is much longer at around 30 s. 33 Even with a severe abnormality, aPTT tests do not exceed 90 s. 34 Figures 3(c) and 3(d) show long-term amplitude and phase stability of the system in distilled water for 10 min, which is more than six times longer than aPTT times of severely abnormal blood samples. The stability measurement yielded a standard deviation of 1.2 mV and a standard deviation of 0.35 deg in phase difference between the drive and readout signals.…”