🩸 Maximum Allowable Blood Loss (MABL)
UseEnter weight, population, initial hematocrit, and the acceptable minimum hematocrit; the tool computes estima…
SourceGross JB. Estimating allowable blood loss: corrected for dilution. Anesthesiology. 1983;58(3):277-2…
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Methodology · worked example, guidelines & full notes
This formula divides by the initial hematocrit; some references use the mean of initial and minimum Hct in the denominator, yielding a slightly different and usually more conservative estimate (original synthesis · not guideline verbatim).
When to use
Enter weight, population, initial hematocrit, and the acceptable minimum hematocrit; the tool computes estimated blood volume and MABL.
How it works
MABL = EBV × (Hct_initial − Hct_min) / Hct_initial, where EBV = weight × population coefficient (adult male 75, female 65, child 70, infant 80 mL/kg).
Key points
- This formula divides by the initial hematocrit; some references use the mean of initial and minimum Hct in the denominator, yielding a slightly different and usually more conservative estimate (original synthesis · not guideline verbatim).
- MABL is a planning estimate.
- The acceptable minimum hematocrit must be lower than the initial value; choose it according to the patient's cardiopulmonary reserve and procedure.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Weight | 60 kg |
|---|---|
| Population | Adult female (65) |
| Initial hematocrit Hct | 42 % |
| Acceptable minimum Hct | 30 % |
→Maximum allowable blood loss (approx.)1114mL
- Estimated blood volume：3900 mL
- Formula：EBV × (Hct_initial − Hct_min) / Hct_initial
| Weight | 60 kg |
|---|---|
| Population | Adult male (75) |
| Initial hematocrit Hct | 42 % |
| Acceptable minimum Hct | 30 % |
→Maximum allowable blood loss (approx.)1286mL
- Estimated blood volume：4500 mL
- Formula：EBV × (Hct_initial − Hct_min) / Hct_initial
Verification & sources · governance
FAQ
Frequently asked questions
- What are the limits and cautions when using Maximum Allowable Blood Loss (MABL)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- Does Maximum Allowable Blood Loss (MABL) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Maximum Allowable Blood Loss (MABL) calculated in practice? Can you show a worked example?
- Inputs: Weight 60 kg, Population Adult female (65), Initial hematocrit Hct 42 %, Acceptable minimum Hct 30 % → Result: Maximum allowable blood loss (approx.) 1114 mL（Estimated blood volume: 3900 mL, Formula: EBV × (Hct_initial − Hct_min) / Hct_initial） Inputs: Weight 60 kg, Population Adult male (75), Initial hematocrit Hct 42 %, Acceptable minimum Hct 30 % → Result: Maximum allowable blood loss (approx.) 1286 mL（Estimated blood volume: 4500 mL, Formula: EBV × (Hct_initial − Hct_min) / Hct_initial）