Some infants can have a massive subaponeurotic hemorrhage, sufficient to cause anemia. The volume of the bleed can be estimated from the head circumference. A more accurate value can be made with a CT scan, but at greater expense.


volume of hemorrhage in mL =

= (((head circumference in cm)^3) - ((normal head circumference in cm)^3)) / (12 * ( π ^ 2))



• Hydrocephalus, microcephalus or other deviations from normal head circumference can result in falsely low or high volume estimates

• Different racial groups will have different expected head circumferences based on gestational age.


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