Choi  in a trial in 2009 found that an intravenous bolus administration of tranexamic acid at 20 mg/kg reduces blood loss compared with placebo during bimaxillary osteotomy.  The aim of this trial was to test whether the use of tranexamic acid in an irrigant fluid would decrease blood loss during orthognathic surgery

Forty patients undergoing bimaxillary osteotomy  were assigned to test (0.05% tranexamic acid in normal saline) or control irrigant fluid (normal saline) use during surgery group by the drawing of random lots ( 20 in each group).  All patients underwent hypotensive anaesthesia and surgery according to standard protocol. Intraoperative blood loss, operative and hypotensive times, preoperative and postoperative haematocrit levels, transfusion of blood product, and amount of irrigant fluid were recorded.

They found that blood loss during bimaxillary surgery was not decreased significantly in the tranexamic acid  group compared with the control group (832.5 ± 315.5 vs 917.5 ± 424.0 mL, respectively, P=0.47).

They concluded:-

Tranexamic acid in an irrigant fluid does not significantly decrease intraoperative blood loss compared with placebo during orthognathic surgery.

Kaewpradub P, Apipan B, Rummasak D. Does tranexamic acid in an irrigatingfluid reduce intraoperative blood loss in orthognathic surgery? A double-blind, randomized clinical trial. J Oral Maxillofac Surg. 2011 Jun;69(6):e186-9. Epub 2011 Mar 12. PubMed PMID: 21398011.