Estimate intracerebral hemorrhage volume using the ABC/2 method from CT imaging. Guides surgical decisions and prognosis in hemorrhagic stroke.
The ICH Volume Calculator uses the ABC/2 method — the most widely used bedside technique for estimating intracerebral hemorrhage volume from non-contrast CT imaging. Developed by Kothari et al. (1996) and validated across numerous studies, this simplified ellipsoid formula provides rapid volume estimation that correlates closely with computer-assisted volumetric analysis (r = 0.93).
Accurate volume measurement is critical in acute hemorrhagic stroke management because ICH volume is one of the strongest predictors of 30-day mortality and functional outcome. The landmark Hemphill ICH Score incorporates volume at the ≥30 mL threshold, and current AHA/ASA guidelines reference hemorrhage volume for surgical decision-making — particularly the STICH II criterion (supratentorial lobar ICH 10-100 mL) and the well-established >15 mL cerebellar hemorrhage surgical threshold.
This calculator supports both the standard ABC/2 method and the modified ellipsoid formula (4/3πr₁r₂r₃). Enter dimensions directly from CT measurement tools, or derive the C dimension from slice thickness and number of affected slices. The tool provides volume classification, surgical considerations based on location, hematoma expansion risk estimates, and expected mass effect — all essential for emergency triage and family counseling.
Rapid and accurate ICH volume estimation is essential in the emergency department and ICU. Volume drives critical decisions including surgical evacuation, transfer to neurosurgical centers, palliative care discussions, and anticoagulation reversal urgency. This calculator eliminates the need for manual ellipsoid math at the bedside. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain.
ABC/2 Volume = (A × B × C) / 2, where A = largest diameter (cm), B = perpendicular diameter (cm), C = craniocaudal extent (cm). When C is derived from slices: C = (slice thickness in mm × number of slices) / 10. Ellipsoid formula: V = (4/3) × π × (A/2) × (B/2) × (C/2).
Result: 21.6 mL — Medium volume
Volume = (4.5 × 3.2 × 3.0) / 2 = 21.6 mL. This Medium-sized hematoma is below the 30 mL surgical threshold for supratentorial ICH but carries 20-35% 30-day mortality. Close monitoring for expansion is warranted.
The ABC/2 formula was published by Kothari, Brott, Broderick, and colleagues in 1996 as a simplified bedside alternative to time-consuming planimetric volumetric analysis. The method models the hemorrhage as an ellipsoid and uses three orthogonal diameters measured on CT. Its simplicity — requiring only a ruler and basic arithmetic — made it immediately practical for emergency settings.
Validation studies demonstrate strong correlation (r = 0.91-0.95) with gold-standard volumetric measurements across different hemorrhage sizes, locations, and CT scanner types. The largest validation study (Webb et al., 2015) confirmed ABC/2 accuracy within ±5 mL for hematomas under 25 mL, though accuracy decreases for very large or irregularly shaped hemorrhages.
ICH volume directly influences acute management decisions:
**Small ICH (< 10 mL):** Medical management with ICU monitoring. Focus on blood pressure control (target SBP 130-150 mmHg per INTERACT2), coagulopathy reversal, and serial CT at 6 hours to detect expansion. Prognosis is generally favorable with 30-day mortality of 10-15%.
**Medium ICH (10-30 mL):** Enhanced monitoring. Consider transfer to neurosurgical center if not already present. Early goals-of-care discussion recommended. The MISTIE III trial evaluated minimally invasive surgery in this range with mixed results.
**Large ICH (30-60 mL):** Consider surgical evacuation based on location (lobar vs. deep), GCS, and patient wishes. The STICH II trial showed potential benefit for lobar hematomas 10-100 mL with GCS ≥ 9 if surgery is performed early. Hemicraniectomy may be discussed for dominant edema.
**Massive ICH (> 60 mL):** Very high mortality (>80%). Surgical intervention rarely changes outcome. Goals-of-care and comfort measures discussion is essential, though care must be taken to avoid self-fulfilling prophecy.
Hematoma expansion remains the most modifiable risk factor after ICH onset. The ATACH-2 and INTERACT2 trials established intensive blood pressure lowering (SBP target 120-140 mmHg) as the primary prevention strategy. Tranexamic acid showed reduced expansion in the TICH-2 trial without improving functional outcome. Rapid reversal of anticoagulation (PCC for warfarin, idarucizumab for dabigatran) is critical for anticoagulant-associated ICH.
The ABC/2 method correlates with planimetric volumetry at r = 0.93 (Kothari 1996). It slightly overestimates irregular hematomas and underestimates oblong ones but is clinically adequate for rapid decision-making.
For supratentorial ICH, the STICH II trial studied early surgery for lobar hematomas of 10-100 mL with GCS ≥ 9. For cerebellar hemorrhage, surgery is generally recommended for volumes > 15 mL or diameter > 3 cm, especially with brainstem compression.
Count all CT slices where the hemorrhage occupies more than 25% of the expected area. Some protocols use >25%, >50%, or >75% area thresholds. The standard Kothari method counts any slice showing hemorrhage.
Hematoma expansion (>33% or >6 mL increase within 24 hours) occurs in 20-40% of patients within 6 hours and independently doubles mortality. The CTA spot sign predicts expansion risk.
ABC/2 is most accurate for relatively elliptical hematomas. For very irregular, multilobar, or C-shaped hemorrhages, planimetric volumetry is preferred. Some studies suggest ABC/3 for irregularly shaped ICH.
The ICH Score uses 30 mL. The FUNC score uses 30 mL and 60 mL cutoffs. For cerebellar ICH, 15 mL is the main threshold. Generally, each 10 mL increase in ICH volume independently raises 30-day mortality.