Tranexamic acid (TXA) is a synthetic form of lysine. In plasma it binds to the lysine binding sites on plasminogen and tissue-plasminogen activator, thereby is a competitive inhibitor of plasminogen. The CRASH-2 (Clinical Randomisation of Antifibrinolytics in Significant Haemorrhage) study, was a randomized controlled study (RCT) of 20,000 trauma patients with bleeding or at risk of bleeding who received either TXA or placebo. There was a reduction in overall mortality in the TXA arm. Subsequent analysis shows there was a reduction in deaths due to exsanguination by 1/3. Since it was published there has been a renaissance in the use of TXA. Over 120 RCTs have been conducted in different groups of surgical patients. They too have shown that TXA reduces mortality and bleeding by 1/3. None of the RCTs have seen an increase in thrombotic events indeed CRASH-2 showed a reduction in arterial thrombotic events.
The use of tranexamic acid in the prevention of PPH has been addressed in a Cochrane review. This found that blood loss greater than 400 ml was less common in women who received tranexamic acid after vaginal birth or caesarean section in the dosage of 1 g or 0.5 g intravenously (RR 0.51, 95% CI 0.36–0.72; two studies, 453 women). Mean blood loss was lower in the group of women who received intravenous tranexamic acid postpartum (mean difference –75.17 ml, 95% CI –108.23 to –42.12 ml; two studies, 361 women). A more recent randomised placebo-controlled trial investigating intravenous tranexamic acid in reducing blood loss at caesarean section concluded that tranexamic acid significantly reduced blood loss associated with surgery, the percentage of women with blood loss greater than 1000 ml and the need for additional uterotonic agents.
The WOMAN study aims to recruit 20,000 women with post partum haemorrhage worldwide randomized to TXA vs. placebo and will finish on 31st March 2016. This and more details of the effects & RCTs of TXA will be discussed
Conflict of interest: the speaker is a PI on the WOMAN study