What is the Emergency Medical Services (EMS) dose of whole blood for a postpartum woman experiencing hemorrhage?

EMS Whole Blood Dosing for Postpartum Hemorrhage

There is no established EMS-specific dosing protocol for whole blood in postpartum hemorrhage, as current guidelines focus on hospital-based component therapy rather than prehospital whole blood administration.

Current Evidence on Whole Blood in PPH

The available evidence on whole blood for postpartum hemorrhage is extremely limited and does not provide EMS-specific dosing:

• Early institutional experience with low-titer O-positive whole blood (LTOWB) in PPH has been reported at only two institutions, with a total of 7 patients receiving 17 units combined, but no standardized dosing protocol was established 1
• These cases involved either emergency release as part of massive transfusion protocols or planned use in high-risk patients with known placental abnormalities, not prehospital EMS scenarios 1
• No adverse reactions were observed, but the sample size is too small to establish safety or efficacy parameters 1

Standard Hospital-Based Blood Product Management

Since EMS whole blood protocols are not established, understanding hospital standards is critical for transition of care:

Initial Resuscitation Approach

• Crystalloid fluids should be used initially until blood loss becomes severe, as overuse increases risk of acute coagulopathy and third-spacing 2
• Once hypovolemia develops, blood products should replace crystalloids 2

Component Therapy Ratios

• After 4 units of RBCs have been transfused, if coagulation results are unavailable and bleeding continues, administer 4 units of FFP and maintain a 1:1 ratio of RBC:FFP until laboratory results are available 3
• A 1:1:1 to 1:2:4 strategy of packed RBCs:FFP:platelets is supported by non-obstetric surgical data 3

Fibrinogen-Focused Management

• Hypofibrinogenemia (fibrinogen <2 g/L) is the most common and earliest factor deficiency in PPH, occurring in 5% of bleeds at 1000 mL and 17% at 2500 mL 3
• Early cryoprecipitate or fibrinogen concentrate may be required before RBC transfusion in severe cases 3
• Target fibrinogen levels should be maintained ≥2 g/L during active bleeding 4

Platelet Transfusion

• Platelet transfusion is rarely required unless PPH exceeds 5000 mL or platelet count is <100 × 10⁹/L from another cause 3
• Transfuse when platelet count falls below 75 × 10⁹/L 3

Critical Adjunctive Therapy: Tranexamic Acid

Tranexamic acid should be administered as soon as PPH is recognized in the prehospital setting:

• Dose: 1 g IV over 10 minutes, with a second 1 g dose if bleeding continues after 30 minutes or restarts within 24 hours 3
• Must be given within 3 hours of birth - benefit decreases by 10% for every 15 minutes of delay, with no benefit and potential harm after 3 hours 3
• This reduces maternal death from bleeding and should be given regardless of bleeding etiology (atony, trauma, etc.) 3

Common Pitfalls to Avoid

• Do not delay tranexamic acid - it is the only evidence-based prehospital intervention that reduces mortality in PPH 3
• Avoid excessive crystalloid resuscitation - this worsens coagulopathy and should be limited until blood products are available 2
• Do not give tranexamic acid beyond 3 hours postpartum - this may be harmful 3
• Recognize that PPH-associated coagulopathy differs from trauma - atony and trauma-related PPH typically do not cause early coagulopathy unless diagnosis is delayed, unlike abruption or amniotic fluid embolus which cause immediate consumptive coagulopathy 3

Practical EMS Approach

Until whole blood protocols are established for EMS use in PPH:

• Prioritize rapid transport to a facility capable of massive transfusion 5
• Administer tranexamic acid 1 g IV immediately if PPH is diagnosed and <3 hours from delivery 3
• Limit crystalloid to maintain perfusion without causing fluid overload 2
• Alert receiving facility early to activate massive transfusion protocol if blood loss is severe (>1500-2500 mL) 2, 5