الفهرس 
Introduction
Mechanism of hemostasisOnly 14 pages are availabe for public view
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Abstract
Coagulation tests and factors measurements have been widely applied in clinical practice; therefore, it is necessary to evaluate the effects of temperature and time from collection on the outcome of these results.Pre-analytical variables including specimen collection, anticoagulant type and concentration, filling status of the sampling tube, transportation, centrifugation, as well as storage and assay method can all affect coagulation test and factor analysis results.
Thus, the aim of this study is to investigate to what extent the storage temperature and time influence the results of routine coagulation tests (PT, aPTT and Fbg) and whether any changes caused by delayed analysis result in a clinically relevant difference.This study was carried out between January 2017 and January 2018 in the thrombosis and hemostasis lab of Clinical Pathology Department, Assiut University hospital after ethical committee approval.>It was included a total number of 220 subjects which divided as follow:For determination of prothrombin time (PT):>• group (Ia) included 40 apparently normal healthy subjects (not receiving anticoagulant). •group (Ib) included 20 subjects receiving anticoagulant in the form of marevan in therapeutic dose.•group (Ic) included 20 subjects having liver cirrhosis (LC).For determination of activated partial thromboplastin time (APTT):•group (IIa) included 40 apparently normal healthy subjects (not receiving anticoagulant).•group (IIb) included 15 subjects receiving anticoagulant in the form of heparin.
• group (IIc) included 25 subjects having liver cirrhosis.
For determination of Fibrinogen:group (IIIa) included 40 apparently normal healthy subjects (not receiving anticoagulant)• group (IIIb) included 20 subjects having different pathologic conditions
Blood samples were delivered into tri sodium citrate B.D tubes (3.2%) as recommended by CLSI for coagulation testing in a ratio of 1:9 (anticoagulant: blood).The centrifugation process was carried out within 2hours of blood sample taking, centrifugation was done for 10 min at 4000 rpm and between 18-250 C. The platelet poor plasma (PPP) was assayed for baseline values for PT, APTT & fibrinogen on Sysmex 1500 apparatus, then it was divided into 3 aliquots groups:The first one was processed at room temperature (18-250C), the second at 40Cand the third one at -200 C, all groups were processed as following:•Pt after 12hr, 24hr and 1 week storage duration•APTT after 12hr storage duration• Fibrinogen after 24hr and 1 week storage durationPT, APTT, Fibrinogen were analyzed on Sysmex CAI5OO using Thromborel’S, Pathromtin Sl. Multifibren U, All assays were performed according to the instructions provided by the manufacturer.Data was analyzed using SPSS version 20. Data was represented as mean, standard deviation, median and range. As regard prothrombin time (PT):•Normal subject samples can be kept at 40C and at-200C up to 12 hours.• Patient receiving marevan samples can be kept at RT, 40C and at-200C up to 1 week.•Patient with LC samples can be kept at RT, 40C up to 24 hours and at-200C up to 1 week.As regard activated partial thromboplastin time (APTT)• Normal subject samples should be measured within 2 hours.• Patient receiving heparin can be kept at RT, 40C and at-200C up to 12 hours.•Patient with LC samples can be kept at RT, 40C and at-200C up to 12 hours.As regard Fibrinogen: • Normal subject samples can be kept at 40C and at-200C up to 24 hours.• Patient with different pathologic condition samples can be kept at 40C and at-200C up to 24 hours