RADIOLOGY: HEAD: Case# 33660: SUBDURAL HYGROMAS SECONDARY TO BIRTH TRAUMA. 3 month old male with previous head trauma. Transcranial ultrasound performed via the fontanelles revealed hypoechoic fluid collections surrounding the brain parenchyma bilaterally. Coronal sections are best for demonstrating fluid collections in the epidural and subdural regions. Imaging through the foramen magnum or posterior fontanelle can be used to look for infratentorial collections. Most subdural collections in the neonatal period are secondary to birth trauma. Additionally, they may result after preexisting meningitis or non-accidental trauma. Typically if an infants head circumference increases after the first 2 weeks of life, a search for extraaxial fluid should be undertaken.