What is the recommended timing for administering Tranexamic acid (TXA) to prevent excessive blood loss during a cesarean section (CS)?

Timing of Tranexamic Acid Administration During Cesarean Section

For prophylactic prevention of excessive blood loss during cesarean section, administer 1 gram of tranexamic acid intravenously over 10 minutes prior to skin incision. 1

Prophylactic Administration Timing

The optimal timing for TXA in cesarean section is before skin incision when used prophylactically to prevent excessive blood loss:

• Administer 1 g IV over 10 minutes prior to skin incision for non-cardiac major surgery, including cesarean section 1
• This prophylactic approach differs fundamentally from therapeutic use for established postpartum hemorrhage 1
• Dose adjustment may be needed based on body weight: 1 g for patients <90 kg and 1.5 g for patients >90 kg 2

Critical Distinction: Prophylaxis vs. Treatment

It is essential to distinguish between two different clinical scenarios with different timing requirements:

Prophylactic Use (Prevention)

• Given before skin incision to prevent excessive bleeding during the planned cesarean section 1, 2
• Reduces mean blood loss by approximately 25-30% compared to placebo 2, 3
• Decreases intraoperative blood loss from approximately 520 mL to 390 mL 2
• Significantly reduces postoperative hemorrhage and need for blood transfusion 3, 4

Therapeutic Use (Treatment of Established PPH)

• Must be given within 3 hours of bleeding onset when treating established postpartum hemorrhage 1, 5
• Efficacy decreases by 10% for every 15 minutes of delay 5
• A second 1 g dose can be given if bleeding continues after 30 minutes or restarts within 24 hours 1
• The WOMAN trial demonstrated reduced bleeding-related mortality when given within 3 hours for established PPH 1

Evidence Supporting Pre-Incision Prophylactic Timing

Multiple high-quality studies support the pre-incision timing for prophylaxis:

• Intraoperative blood loss is significantly reduced when TXA is given 10-20 minutes before skin incision 2, 6, 4, 7
• Postoperative blood loss within 24 hours is also significantly decreased 3, 6
• The incidence of postoperative anemia and blood transfusion requirements are substantially lower 3
• No adverse maternal or neonatal effects have been documented with this timing 2, 4, 7

Important Caveats

Do not confuse prophylactic cesarean section dosing with postpartum hemorrhage treatment:

• The 3-hour window applies only to established bleeding/PPH, not prophylactic use 1, 8
• TXA is not indicated for intrauterine miscarriage, first or second trimester pregnancy loss, or bleeding from retained products before viable delivery 8
• Giving TXA beyond the 3-hour window for established PPH may be harmful 8

Dosing Algorithm for Cesarean Section

For elective or scheduled cesarean section (prophylaxis):

• 1 g IV over 10 minutes before skin incision 1, 2
• Consider 1.5 g if body weight >90 kg 2

If postpartum hemorrhage develops during or after cesarean:

• 1 g IV over 10 minutes within 3 hours of bleeding onset 1
• Second dose of 1 g if bleeding continues after 30 minutes or restarts within 24 hours 1

Renal Impairment Consideration

• Dose adjustment is recommended in patients with impaired renal function based on serum creatinine levels 5