What are the indications for transfusion in a pregnant woman with non-traumatic disseminated intravascular coagulation (DIC)?

Transfusion Indications in Non-Transfusion Dependent Thalassemia (NTDT) During Pregnancy

I notice there may be confusion in the question terminology. The evidence provided addresses DIC (disseminated intravascular coagulation) in pregnancy, not NTDT (non-transfusion dependent thalassemia). I will answer based on the evidence provided, which focuses on transfusion indications for pregnant women with coagulopathy and hemorrhage.

Primary Transfusion Threshold

Transfuse red blood cells when hemoglobin falls below 7.0 g/dL in pregnant women, and consider transfusion for hemoglobin 7.0-8.0 g/dL if cardiac disease or ongoing bleeding is present. 1

• Transfuse one unit at a time and recheck hemoglobin before each subsequent unit, unless active hemorrhage is occurring 1, 2
• Each unit of packed red blood cells should increase hemoglobin by approximately 1 g/dL 3

Hemorrhage-Specific Transfusion Protocol

Initial Blood Product Administration

In obstetric hemorrhage without known coagulation results, withhold fresh frozen plasma (FFP) until four units of red blood cells have been given, unless early coagulopathy is diagnosed on coagulation screening. 4

• After four units of RBCs with ongoing bleeding and no coagulation results available, infuse four units of FFP and maintain 1:1 ratio of RBC:FFP until hemostatic test results are known 4
• This approach prevents excessive FFP transfusion in postpartum hemorrhage associated with atony or trauma, which is less likely to involve hemostatic impairment unless diagnosis is delayed 4

Fibrinogen-Directed Transfusion

Prioritize fibrinogen replacement when Clauss fibrinogen is <3 g/L with ongoing bleeding, as this strongly predicts progression to massive obstetric bleeding (>2500 mL). 4

• Severe hypofibrinogenemia (fibrinogen <2 g/L) occurs in approximately 5% of bleeds at 1000 mL and is associated with placental abruption, amniotic fluid embolus, and severe bleeding with sepsis and pre-eclampsia 4
• Administer cryoprecipitate or fibrinogen concentrate to maintain fibrinogen >1.5-2.0 g/L 1, 2
• Early use of cryoprecipitate or fibrinogen concentrate before RBC transfusion may be required in conditions causing early coagulopathy, with repeated administration if bleeding continues 4
• In pregnancy, fibrinogen <3 g/L carries a pregnancy-specific DIC score weight of 25 points, and fibrinogen ≤2 g/L has 100% positive predictive value for severe postpartum hemorrhage 4

Platelet Transfusion Thresholds

Transfuse platelets when platelet count is <75 × 10⁹/L in the setting of obstetric hemorrhage. 4

• Platelet transfusion is rarely required unless postpartum hemorrhage exceeds 5000 mL or platelet count was <100 × 10⁹/L from another cause prior to hemorrhage 4
• Maintain platelet count >75 × 10⁹/L during active bleeding 2

Coagulation Monitoring in Pregnancy

Laboratory Parameters Requiring Transfusion

Use PT ratio and APTT ratio ≥1.5 as the cutoff for coagulopathy in pregnancy, rather than absolute values in seconds. 4

• PT and APTT are physiologically shortened in pregnancy (median PT 9.60 seconds, APTT 31.00 seconds at 36 weeks) due to increased coagulation factors 4
• Any prolongation of PT and APTT above normal non-pregnant range may indicate factor depletion and should be managed with FFP 4
• PT and APTT prolongation is less common than hypofibrinogenemia, affecting only 1% of hemorrhages at 1000 mL and typically occurring at bleed volumes >4000 mL 4

Pregnancy-Specific DIC Diagnosis

Apply the pregnancy-specific DIC score using three components: fibrinogen concentration, PT difference (patient's PT minus laboratory control), and platelet count. 5

• At a cutoff ≥26 points, this score has 88% sensitivity, 96% specificity, positive likelihood ratio of 22, and negative likelihood ratio of 0.125 5
• Standard ISTH DIC scoring may not be appropriate in pregnancy due to physiologic hypercoagulability 5, 6

Adjunctive Hemostatic Therapy

Tranexamic Acid Administration

Administer tranexamic acid 1 g IV immediately when postpartum hemorrhage is identified (>500 mL vaginal delivery, >1000 mL cesarean delivery), ideally within 3 hours of bleeding onset. 4, 1, 2

• Tranexamic acid reduces total blood loss and should be given if severe hemorrhage is confirmed 4, 1
• Hyperfibrinolysis is common in early postpartum hemorrhage 4, 7

Critical Pitfalls to Avoid

Do not rely on visual estimation of blood loss, as it consistently underestimates actual blood loss by 30-50% and delays appropriate intervention. 1, 2

• Use volumetric and gravimetric techniques to measure cumulative blood loss accurately 1, 3
• Systematically weigh blood-soaked pads and change bedding immediately after delivery for accurate measurement 2

Do not wait for laboratory results to initiate resuscitation in obvious severe hemorrhage with hemodynamic instability. 1, 2

• Calculate Shock Index (heart rate ÷ systolic blood pressure): values >1 indicate hemodynamic instability requiring immediate intervention 1, 3
• Assemble multidisciplinary team immediately if bleeding exceeds 1000 mL after cesarean delivery 1

Do not use protocol-driven FFP transfusion in all obstetric hemorrhages, as this leads to excessive transfusion in most cases of atonic or traumatic bleeding without coagulopathy. 4, 2

Ongoing Monitoring Requirements

Recheck hemoglobin 4-6 hours after transfusion completion or sooner if clinical deterioration occurs. 1, 3

• Continue vital sign monitoring every 1-2 hours for the first 24 hours postpartum 1, 3
• Monitor urine output, as oliguria indicates ongoing hypovolemia or progression of complications 1, 3
• Repeat coagulation studies if bleeding continues, and withhold blood components if bleeding has stopped 4