We aimed to define levels of agreement (LOA) between emergency radiologists (RAD) and emergency medicine (EM) physicians for estimating bleed volume in intracranial hemorrhages (ICH) using ABC/2 formula.

A prospective study of a curated sample of head CT's were performed in an emergency department. Raters independently reviewed the scans. Perpendicular maximal dimensions (A and B) were measured on an axial CT image. The ‘C’ dimension was a product of slice thickness and number of slices with visible bleed.

A hundred CT head examinations were included with a median age of 50 years (IQR 43 to 57). The median bleed volume was 11.2 mL (IQR 6.6–18.6) per the index radiologist estimations. The overall mean of differences between the RAD mean and the EM mean estimated bleed volume was 0.3 (95% CI -1.5 to +1.7) in milliliters. The percentage difference between EM and RAD expressed as median was 1.9% (IQR -13.4% to +14.1%). Compared to the index RAD the mean of differences for bleed volume [rater, mean (95% CI) in milliliters] were: second RAD, 1.19 (1.14 to 1.24); EM attending, 1.05 (0.98 to 1.13); senior fellow, 1.05 (1.00 to 1.10); junior fellow, 1.19 (1.06 to 1.33); senior resident, 1.29 (1.19 to 1.39); junior resident, 1.11 (1.03 to 1.20). The difference between EM versus radiologist, junior versus senior EM physician estimation of bleed size was clinically insignificant.

Excellent level of agreement was found between emergency physicians and emergency radiologists for estimating ICH bleed volumes using ABC/2 formula.