40 Chapter 3 Furthermore, there is mild agreement between the tests (K = 0.22), which indicates that with regard to detection of impaired platelet function in patients with undefined bleeding disorders, LTA and flow cytometry might provide supplemental information (20). In addition to impaired VWF and platelet function, impaired coagulation might also be a factor for more severe menstrual bleeding. Most laboratories quantify coagulation with clotting assays, (prothrombin time (PT) or activated partial thromboplastin time (APTT)). Although prolonged PT or APTT might be suitable for detection of factor deficiencies, they are not sensitive enough to detect mildly impaired coagulation and they are not suitable for studying thrombosis risk. There is now growing interest for thrombin generation (TG) testing as alternative for the PT and APTT, because it gives a more complete picture of the coagulation characteristics of an individual. Still TG is a global test, which requires specific follow-up testing to define the real coagulation defects. Although TG is not yet implemented for routine clinical diagnostics, it is on many items superior to routine coagulation tests, because it covers the whole spectrum of coagulation initiation, propagation, acceleration and inhibition, while routine coagulation tests cover only the first few seconds of coagulation (21). In this study, the testable hypothesis is that platelet function testing by flow cytometry and measurements of TG, VWF levels and VWF function give insight in the involvement of haemostasis in the prevalence of HMB. We have performed our study in women with HMB at the general gynaecology clinic of the teaching hospital of Apeldoorn (Gelre Hospitals) in the Netherlands. MATERIAL AND METHODS Patients A total of 60 Caucasian patients with unexplained HMB, who are treated between January 2010 and January 2013 with second- generation endometrial ablation (SGEA) at the gynaecology clinic of the teaching hospital of Apeldoorn (Gelre Hospitals) in the Netherlands, were invited to participate in this study. Patients did not take any drugs, estrogens, progestogens, aspirin or other non- steroidal anti-inflammatory drugs (NSAIDs) for at least 2 weeks before blood drawing. None of the included patients had received transfusions during the 4 weeks prior to their blood draws. Two pa- tients dropped out of the study due to inappropriate blood collection. The final study group consisted of 58 females ranged in age from 40 to 60 years (median age: 48.4). They self-identified their ethnicity as Caucasian (100%). On each day, patient samples were tested and blood for baseline measurements was also obtained from one healthy control. In total, 26 controls (median age: 36.9 years, range 24-50 years) were recruited among students and employees at the Gelre Hospitals. The medical ethical review board of the Gelre Hospitals approved the study protocol after written informed consent was obtained according to the ethical guidelines of the 1975 Declaration of Helsinki (2013). Blood was collected aseptically by antecubital puncture into vac- uum tubes VACUETTE® TUBE 3 mL 9NC Coagulation sodium citrate 3.2% (Greiner Bio One, Austria). A fraction of 40 μL was taken for flow cytometric platelet function, and VWF function testing and assays were performed within 3 hours from collection. The remaining blood was double centrifuged at 2630 g for 10
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