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Hematology

Maximum Allowable Blood Loss (MABL)

Estimates the volume of blood loss that can occur before transfusion is required, from the estimated blood volume and the acceptable haematocrit fall.

Inputs

FieldUnitNotes
Weight kg 0.3–150
Age band
Initial haematocrit % 10–70
Minimum acceptable haematocrit % Often 21–25%

FAQ

What is the Maximum Allowable Blood Loss (MABL)?

Estimates the volume of blood loss that can occur before transfusion is required, from the estimated blood volume and the acceptable haematocrit fall.

What inputs does the Maximum Allowable Blood Loss (MABL) need?

Weight (kg), Age band, Initial haematocrit (%), Minimum acceptable haematocrit (%).

Related guides

Maximum Allowable Blood Loss (MABL): The Pediatric Transfusion Trigger

MABL estimates how much blood a child can lose before transfusion — MABL = EBV × (Hct_initial − Hct_min) / Hct_initial. The formula, an age-band worked example, and the conservative variant.

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