Massive Obstetric Haemorrhage and Transfusion
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Direct answer
Massive obstetric haemorrhage is blood loss large enough to cause shock, usually ongoing and needing several units of blood within a short period. Management combines early recognition, a massive transfusion protocol and balanced replacement of red cells, plasma and platelets, with fibrinogen and ionised calcium monitored. Transfusion decisions follow the bleeding pattern, the clinical state and laboratory results rather than a fixed formula alone.
What you must remember
- Shock classes: Graded from I to IV by estimated blood loss, heart rate, blood pressure and mental state, and the grade guides the response.
- Protocol trigger: The massive transfusion protocol is activated when shock and ongoing bleeding coexist, without waiting for a set volume or laboratory results.
- Balanced ratio: Packed red cells, fresh frozen plasma and platelets are given in a balanced ratio, close to 1:1:1 in many protocols, adapted locally.
- Fibrinogen: Cryoprecipitate is given when fibrinogen falls below about 2 g/L, the usual obstetric target.
- Calcium: Citrate in transfused products binds calcium, so ionised calcium is monitored and replaced, commonly as calcium gluconate.
- Lethal triad: Hypothermia, acidosis and coagulopathy feed one another (hypocalcaemia is added in the lethal diamond), so warmed products are used and correction is continued.
- Last resort: Recombinant factor VIIa and hysterectomy are considered when bleeding continues despite the measures above, under specialist guidance.
Grading shock to match the response
Shock is graded by estimated blood loss and haemodynamic signs, and the grade decides how quickly products are given. The table follows the classes used in trauma and obstetric teaching, and blood loss is often underestimated, so clinical signs carry weight.
| Class | Blood loss (approximate) | Clinical picture | Response |
|---|---|---|---|
| I | Under 15 percent | Minimal change | Observe, uterotonics, two large-bore IV lines |
| II | 15 to 30 percent | Tachycardia with normal pressure | Crystalloid, cross-match, close monitoring |
| III | 30 to 40 percent | Hypotension, confusion, reduced urine output | Blood products and activation of the protocol |
| IV | Over 40 percent | Severe hypotension, reduced consciousness | Immediate protocol and surgical control |
Visible blood loss underestimates the true loss, so a rising heart rate and falling pressure should trigger the protocol early.
Urine output, capillary refill and mental state change before laboratory values do, so they are repeated frequently during resuscitation. Serial haemoglobin and lactate levels help track progress but lag behind the bleeding.
Where the exam tries to catch you
Questions test the classes, the fibrinogen target and the role of crystalloid.
- Trap: Waiting for haemoglobin to fall before starting transfusion. Correct: Haemoglobin lags behind acute loss, so clinical shock and ongoing bleeding should trigger products early.
- Trap: Giving large volumes of crystalloid alone. Correct: Crystalloid dilutes clotting factors and red cells, so blood components are needed in shock.
- Trap: Giving plasma without checking fibrinogen. Correct: Fibrinogen often falls early in obstetric haemorrhage, so cryoprecipitate guided by levels is the targeted replacement.
- Trap: Assuming a normal platelet count excludes coagulopathy. Correct: Clotting factors and fibrinogen can be low even when platelets are normal, so coagulation tests are needed.
Frequently asked questions
What is class IV haemorrhagic shock in obstetrics?
Class IV haemorrhagic shock is blood loss above 40 percent of blood volume, with severe hypotension and reduced consciousness. It needs immediate massive transfusion and surgical control of the source of bleeding. Resuscitation proceeds alongside the surgical plan.
What fibrinogen level prompts cryoprecipitate in obstetric bleeding?
Cryoprecipitate is given when fibrinogen falls below about 2 g/L in obstetric bleeding, with the aim of keeping it above that level. Levels are rechecked repeatedly during massive haemorrhage. Laboratory values should guide therapy rather than fixed volumes alone.
Why is ionised calcium monitored during massive transfusion?
Citrate in transfused plasma and products binds calcium, lowering the ionised calcium needed for clotting and cardiac function. Calcium is replaced, commonly as calcium gluconate or calcium chloride, to keep levels adequate. Low calcium worsens coagulopathy and haemodynamic instability.
What does the massive transfusion protocol achieve?
The massive transfusion protocol is a pre-agreed system that releases blood components quickly during major haemorrhage. It provides a balanced supply of red cells, plasma and platelets without waiting for detailed tests. Its main benefit is speed, which reduces the time spent in shock.