ToolsCalculators
Maximum allowable blood loss (ABL) without transfusion
Maximum allowable blood loss (ABL) without transfusion
Patient category (average blood volume)
Weight
Starting hematocrit
%
Lowest acceptable hematocrit
%
Complete the fields above to see the result.
When to use
- Anticipating, before or during surgery, how much blood loss can be tolerated before transfusion is likely needed.
Formula
EBV = weight x average blood volume per kg. ABL = EBV x (starting Hct - lowest acceptable Hct) / average Hct, where average Hct = (starting + lowest acceptable)/2.
Pearls and pitfalls
- Corrects for the fact that hematocrit falls progressively as blood is lost and replaced with crystalloid/colloid, unlike the simpler uncorrected formula.
- Treat the transfusion trigger (lowest acceptable Hct/Hb) as an individualized clinical decision, not a fixed number.