ICH Volume Calculator (ABC/2 Method)
Enter CT-based measurements to estimate intracerebral hemorrhage (ICH) volume in mL.
What this ICH volume calculator does
This tool estimates intracerebral hemorrhage volume using the classic ABC/2 approach. It is widely used in emergency neurology, neurocritical care, and stroke workflows because it is quick, practical, and usually close enough for bedside decisions.
ABC/2 volume (mL) = A × B × C ÷ 2
Where:
- A = largest hemorrhage diameter (cm)
- B = diameter perpendicular to A (cm)
- C = hemorrhage depth (cm), often estimated as slices × slice thickness
Why ICH volume matters
Hemorrhage volume is one of the most important predictors of outcome in spontaneous ICH. Larger volumes are generally associated with higher mortality, greater neurological deficit, and more aggressive management planning. Volume may also feed into scoring systems and discussions about monitoring intensity, transfer, and prognosis.
Typical practical thresholds (educational use)
- < 30 mL: often categorized as smaller hemorrhage burden.
- 30–60 mL: moderate volume range.
- > 60 mL: large hemorrhage burden with high clinical concern.
How to measure A, B, and C correctly
Step 1: Pick the largest slice
Find the CT slice where the hemorrhage appears largest in cross-sectional area. On that slice, measure:
- A as the maximum long-axis diameter.
- B as the maximum short-axis diameter at right angles to A.
Step 2: Estimate depth (C)
Count how many slices include visible hemorrhage, then multiply by the slice thickness. Convert mm to cm.
C (cm) = [number of slices × thickness (mm)] ÷ 10
Step 3: Apply ABC/2
Insert A, B, and C into the formula. Because 1 cm³ ≈ 1 mL in this context, the result is interpreted in mL.
Worked example
| Measurement | Value |
|---|---|
| A diameter | 5.0 cm |
| B diameter | 3.2 cm |
| Slices with blood | 6 |
| Slice thickness | 5 mm |
| C depth | (6 × 5)/10 = 3.0 cm |
| Estimated volume | (5.0 × 3.2 × 3.0)/2 = 24.0 mL |
Limitations of ABC/2
ABC/2 assumes an approximately ellipsoid shape. Real-world hematomas can be irregular, lobulated, multifocal, or mixed-density, which can reduce accuracy.
- May overestimate or underestimate in irregular bleeds.
- Intraventricular extension and complex anatomy may need more advanced volumetric methods.
- Slice thickness and measurement technique can introduce error.
Tips for better consistency
- Use the same window/level settings during measurement.
- Measure A and B on the exact same slice.
- Double-check slice count for C.
- Recalculate if scan quality is poor or edema obscures boundaries.
Quick FAQ
Is the result in mL or cm³?
For this purpose, they are effectively equivalent: 1 cm³ is approximately 1 mL.
Can I use this for all hemorrhage types?
It is mainly used for intraparenchymal ICH estimation. Other hemorrhage patterns may require separate assessment methods.
Is this enough for diagnosis or treatment?
No. It is an estimation tool only. Diagnosis and treatment require full clinical evaluation, neuroimaging interpretation, and specialist judgment.
Bottom line
The ICH volume calculator is a fast, practical way to estimate hemorrhage burden using CT measurements. ABC/2 remains useful because it is simple and clinically familiar, especially when decisions must be made quickly. Use it as a structured aid—not a replacement for expert medical care.