In 3 plastic surgery centers, the investigators randomized patients in a double-blind, randomized, controlled trial comparing the clinical outcomes of different administration routes of TXA, intravenous versus subcutaneous versus placebo between January 2019 to February 2020. The study was approved by the Ethics committee at the central coordinating center and at each of the participating sites. The centers of the study were, Dhara clinic, Bogota, Colombia, Centro Medico de las Americas clinic, in Mérida, Mexico and Innovare hospital in Jalisco, Mexico. Once a month, the investigators performed only meetings between the researcher coordinator and delegates from each of the centers to audit the data collection and information registration.

During the preoperative consultation, the study interventions were explained clearly to each participants. Participants were given adequate time to ponder the information, had any questions answered and gave their free and voluntary consent. A total of 141 participants were recollected. The primary outcome was the difference regarding to hemoglobin loss points between groups. All patients had hemoglobin and hematocrit tests taken prior to surgery, 24 hours postoperatively and 5 days postoperatively. The investigators determined the hemoglobin loss points in each group by deduct the postoperative hemoglobin at day one to the preoperative hemoglobin (For hemoglobin loss at day 1) and the postoperative hemoglobin at day five to the preoperative hemoglobin (For hemoglobin loss at day 5). As a secondary outcome, the investigators performed a subgroup analysis to determine the difference in hematological parameters (hemoglobin and hematocrit) between the groups.

Sample size and Statistical Analysis Sample size was calculated using the online app from sealed envelope where 96 patients were required to have a 90% of chance of detecting, as significant at the 5% level, a difference between the mean postoperative Hb value from 10.5 g/dl in the control group to 11.5 g/dl in the experimental group and an estimated standard deviation (SD) of 1.5 g/dl. Since, the investigators planned two experimental approaches: Subcutaneous (SC) TA and Intravenous (IV) TA; 141 patients were randomized into 3 groups: 1. IV-TA group (n=47), 2. SC-TA group (n=47) and NS group. Demographic and clinical characteristics were described, hematological parameters were analyzed per group before surgery, at the immediate post-operative period, and at the fifth post-operative day. The descriptive analysis was made through means and medians according to the distribution of variables.

For categorical variables, counts and percentages were used. The quantitative variables with parametric distribution were compared using ANOVA, and for variables with non-parametric distribution using Kruskal-Wallis test, while the frequencies of the qualitative variables were compared using Chi2 test. We used a boxplot to illustrate the differences between the means of the hemoglobin by group. Bilateral hypotheses were formulated at two tails with significance level less than 0.05. The data were collected in Microsoft excel and the statistical analysis were performed in the statistical program STATA version 15.0.