Postpartum hemorrhage (PPH) is the leading cause of maternal death. Tranexamic acid (TA) (Exacyl® Sanofi France), an antifibrinolytic drug, reduces bleeding and transfusion need in major surgery and trauma (1). In ongoing PPH following vaginal delivery (2), a high dose of TA decreased the volume and duration of PPH, the transfusion need and the maternal morbidity, while early fibrinolysis was inhibited (3). Prophylactic use of TA limited the postoperative bleeding in elective non hemorrhagic caesarean section (CS). (1, 4) TA efficiency in the hemorrhagic caesarean context has not been previously published.~TA doses range vary from 2,5 to 100 mg/kg and side effects were observed with the largest doses.(1,4) Pharmacokinetics old data concerned non hemorrhagic patients.(1) WOMAN ongoing international trial using a one gram dose have a mortality reduction objective.(5) The optimal dose for ongoing caesarean PPH has to be determined.~Aim of the study:~The aim of the multicenter randomized double blind placebo control therapeutic and pharmaco-biological dose ranging study TRACES is to measure the effect on blood loss reduction of a single intravenous infusion of two doses regimens of TA administered at the onset of an active PPH (>800mL) during elective or non-emergent CS and to correlate this clinical effect with the biological effect of fibrinolysis inhibition and the pharmacodynamic measure of TA uterine bleeding and venous blood concentration.~Statistical method:~The sample size computation is based on the expected difference between the placebo group and the low dose. On the base of EXADELI trial results, the investigators calculated that a total of 342 subjects (114 per group) is required, For the main objective, the blood loss volume measured in each experimental group (low dose and high dose) will be compared to that of the placebo group by using an analysis of covariance adjusted for baseline blood loss volume. In cases of non-normal distribution, relative blood loss volume will be calculated and compared using a Mann-Whitney U test. Analyses will be done on an intention-to-treat basis and all statistical tests will be performed with a 2-tailed alpha risk of 0.05. The sample size computation for the pharmaco-biological substudy have been calculated regarding the inhibition of fibrinolysis (D Dimers increase between 30 and 120 minutes negative or null (EXADELI trial 11)). The NNS for this substudy is 48 patients in each of the 3 hemorrhagic groups and 48 patients in the reference non-hemorrhagic group for a total of 192 patients. These substudy hemorrhagic patients will be selected from the experimental groups as the first 144 patients for which the TA concentration and plasmin peak specific sampling will be completed regarding the blood collection and congelation organisation in each center.~Expected research benefit:~The project is aimed to answer for a current clinical practice question: Timing and dose of TA to reduce blood loss and maternal morbidity due to active hemorrhage during CS in order to determine the optimal and minimal TA dose to obtain the better efficacy and the limitations of side-effects.
TRACES trial is a multicenter randomized double blind placebo control therapeutic and pharmaco-biological dose ranging study to measure the effect on blood loss reduction of a single intravenous infusion of two doses regimens (standard dose and low dose) of TA administered at the onset of an active PPH (>800mL) during elective or non-emergent CS and to correlate this clinical effect with the biological effect of fibrinolysis inhibition and the pharmacodynamic measure of TA uterine bleeding and venous blood concentration.