Appropriate Use of Blood Components in Obstetrics – Short Notes (MS OBG)

Introduction

Indications for Blood/Component Therapy in Obstetrics

• Postpartum hemorrhage (atonic, traumatic, tissue, thrombin causes - the "4 T's")
• Antepartum hemorrhage: placenta previa, abruptio placentae, placenta accreta spectrum
• Disseminated intravascular coagulation (abruption, AFE, severe preeclampsia/HELLP, sepsis, retained dead fetus)
• Amniotic fluid embolism with coagulopathy and collapse
• Ruptured ectopic pregnancy / ruptured uterus
• Severe antenatal anemia not responding to medical management, or symptomatic anemia near term
• Rh-negative mothers requiring anti-D immunoglobulin prophylaxis (a blood-derived product, not a "transfusion" per se but part of component use in obstetrics)

Blood Components and Their Obstetric Use

• Corrects oxygen-carrying capacity loss from acute hemorrhage or severe symptomatic anemia
• Trigger usually clinical (ongoing bleeding, hemodynamic instability) rather than a fixed Hb cutoff, though Hb < 7 g/dL is a common threshold for transfusion in stable postpartum anemia
• 1 unit raises Hb by roughly 1 g/dL

• Contains all coagulation factors (no platelets); used to replace clotting factors in DIC, dilutional coagulopathy of massive hemorrhage, or when fibrinogen/PT-INR are deranged
• Given empirically in massive transfusion protocols alongside PRBC (see ratio below) rather than waiting for lab results in catastrophic hemorrhage

• Rich in fibrinogen, factor VIII, von Willebrand factor, factor XIII, fibronectin
• First-line for hypofibrinogenemia (fibrinogen < 100-150 mg/dL), which occurs early and severely in obstetric hemorrhage (abruption, AFE) - fibrinogen falls disproportionately fast in obstetric bleeding compared to trauma
• Target fibrinogen > 100-150 mg/dL in active obstetric hemorrhage

• Indicated when platelet count falls below 50 x 10^9/L in the setting of active bleeding or before an operative delivery/procedure, or in severe preeclampsia/HELLP with bleeding risk
• Given as a "6-pack" or single-donor apheresis unit

• Rarely used now except in resource-limited settings; fresh whole blood can supply RBCs, plasma factors and some platelet activity together, useful in massive obstetric hemorrhage where component therapy is unavailable

• Not for hemorrhage but a standard obstetric blood-derived product: given to Rh-negative unsensitized women at 28 weeks and within 72 hours of delivery of an Rh-positive baby, and after any sensitizing event (abortion, ectopic, APH, amniocentesis, external cephalic version) to prevent Rh isoimmunization

Massive Transfusion Protocol (MTP) in Obstetrics

• Activated for ongoing hemorrhage anticipated to require transfusion of the woman's total blood volume, or > 4 units PRBC in an hour with ongoing loss, or hemodynamic instability unresponsive to initial resuscitation
• Empiric component ratio: PRBC : FFP : Platelets approximately 1:1:1 (mirrors trauma MTP data, adapted for obstetrics)
• Early cryoprecipitate/fibrinogen concentrate is emphasized because obstetric hemorrhage causes early hypofibrinogenemia unlike trauma
• Point-of-care viscoelastic testing (TEG/ROTEM) increasingly used to guide targeted component replacement once available, rather than relying only on fixed ratios
• Adjuncts: tranexamic acid (TXA) 1 g IV within 3 hours of bleeding onset, repeated once if needed - reduces bleeding-related mortality and transfusion requirement in PPH (WOMAN trial data, reaffirmed by recent systematic reviews)
• Warm the patient and fluids, avoid excess crystalloid (dilutional coagulopathy), correct hypocalcemia (citrate in transfused blood chelates calcium)

Practical Points for Exam

• Cross-match and "group and save" for all women at high risk of hemorrhage (previa, accreta, previous PPH, multiple pregnancy, grand multipara)
• Cell salvage is increasingly used intraoperatively (e.g., cesarean for placenta accreta) to reduce allogeneic transfusion need
• Massive obstetric hemorrhage management is a team-based protocol (obstetrician, anesthetist, blood bank, nursing) - delay in component availability is a preventable cause of maternal death

Recent Evidence (flag for updates beyond textbook)