ICH Volume
Calculate intracerebral hemorrhage (ICH) volume using the ABC/2 method from CT scan measurements. Free online medical calculator with clinical interpretation and charts.
About This Calculator
What is the Intracerebral Hemorrhage (ICH) Volume Calculator?
This ICH Volume Calculator uses the validated ABC/2 method (also called the ABC CT formula) to estimate the volume of a parenchymal hemorrhage from CT scan measurements. Originally described by Kothari et al. in 1996, this method provides a quick and reliable estimate of hemorrhage volume that correlates well with planimetric measurements for ellipsoid-shaped bleeds.
The formula works by multiplying the three dimensions of the hemorrhage: A (maximum length in cm), B (perpendicular width in cm), and C (slice thickness multiplied by number of slices in cm). The result is divided by a shape factor — 2 for ellipsoid or round hemorrhages, or 3 for irregular, separated, or multilobulated bleeds. ICH volume is typically expressed in milliliters (mL), which is equivalent to cubic centimeters (cm³).
An ICH volume greater than 60 mL is associated with poor prognosis, while volumes above 30 mL contribute to higher ICH scores and increased 30-day mortality. This tool is designed for healthcare professionals including neurologists, neurosurgeons, radiologists, and emergency physicians who need rapid hemorrhage volume estimation for clinical decision-making.
Disclaimer: This calculator is for educational and reference purposes only. It should not replace professional medical judgment. Always verify measurements with radiology software and consult clinical guidelines for treatment decisions.
Regional Notes
United States: CT slice thickness in US practice typically ranges from 2.5-5 mm for standard head CT. The ABC/2 method is widely taught in US neurology and neurosurgery training programs.
United Kingdom: NICE guidelines recommend CT imaging for suspected intracerebral hemorrhage within one hour of presentation. The ABC/2 method is standard practice in UK stroke services.
India: Head CT is widely available across Indian tertiary care centers. Standard slice thickness is typically 5 mm. The ABC/2 method is used per international stroke guidelines adapted by the Indian Stroke Association.
Frequently Asked Questions
What is the ABC/2 method for ICH volume calculation?
The ABC/2 method estimates intracerebral hemorrhage volume from a CT scan. A is the maximum hemorrhage diameter, B is the perpendicular width, and C is calculated from slice thickness multiplied by the number of slices showing hemorrhage. The product is divided by 2 for ellipsoid bleeds or by 3 for irregular shapes.
What is considered a large ICH volume?
An intracerebral hemorrhage volume greater than 60 mL is considered a poor prognostic marker. Volumes above 30 mL are associated with significantly higher mortality and worse functional outcomes. The ICH score uses 30 mL as one of its criteria for 30-day mortality prediction.
Why divide by 2 or 3 in the ICH volume formula?
The division accounts for the shape of the hemorrhage. Ellipsoid or round hemorrhages use divisor 2 because the volume of an ellipsoid is approximately A×B×C/2 when approximating pi as 3. Irregular, separated, or multilobulated hemorrhages use divisor 3 to account for more complex geometry.
How do you count CT slices for ICH volume?
Each CT slice where hemorrhage covers 75% or more of the slice counts as 1 slice. If coverage is between 25% and 75%, count it as 0.5 slices. Slices with less than 25% hemorrhage coverage are not counted. This standardized method was established by Kothari et al. in 1996.
Is the ABC/2 method accurate?
The ABC/2 method shows good correlation with planimetric volume measurement (computer-assisted tracing), especially for ellipsoid-shaped hemorrhages. However, it may overestimate volume for irregular or multilobulated bleeds. For these cases, using divisor 3 or planimetric methods is recommended for better accuracy.
What is the ICH score and how does volume relate to it?
The ICH score is a clinical grading scale that predicts 30-day mortality after intracerebral hemorrhage. ICH volume ≥30 mL contributes 1 point to the score. Other factors include Glasgow Coma Scale, intraventricular hemorrhage, infratentorial origin, and age ≥80 years. The score ranges from 0 to 6.
How is ICH volume used in clinical practice?
ICH volume helps clinicians assess hemorrhage severity, guide treatment decisions, and predict patient outcomes. Large volumes (>30 mL) may warrant surgical evacuation, while smaller bleeds are managed medically. Volume measurement also helps track hemorrhage expansion on follow-up imaging.
What causes intracerebral hemorrhage?
Common causes include hypertension (most common), cerebral amyloid angiopathy, anticoagulant therapy, arteriovenous malformations, aneurysms, head trauma, bleeding disorders such as hemophilia, and illicit drug use including cocaine and methamphetamines. Spontaneous ICH without identified cause also occurs.