Purpose or Case Report: Head ultrasound (US) remains the primary screening tool for intracranial pathology in premature infants, most notably germinal matrix hemorrhage. Advances in neonatal medicine have improved survival rates of infants born at 22 to 25 weeks’ gestation. These infants demonstrate unique developing anatomy when compared to premature infants of more advanced gestational ages. Infants delivered between 20 weeks/0 days and 25 weeks/6 days of gestation have been defined as ‘periviable births’ by the American College of Obstetricians and Gynecologists. To date there is no dedicated literature describing head US findings in this population. The purpose of this review is to describe normal anatomy and pathology in the periviable population on head US.
Methods & Materials: A single-center, retrospective review of live births between 20 weeks/0 days and 25 weeks/6 days gestational age over a 2.33 year period was performed. Patient demographics and delivery details were evaluated. Head US images and reports were reviewed for both screening and clinically directed studies.
Results: 21 live births were identified. 7 patients were deceased on day of life (DOL) 0 and did not undergo head US. Of the remaining 14 patients (8 female; average birth weight 679.1 g), most had initial US performed on DOL 1 (range DOL 0-3) with a median of 6 total studies per patient (range 1-24). Two patients with normal initial sonographic findings were deceased by DOL 14. 12 patients survived beyond the date of their final follow up US, of which seven (58%) had normal head US findings throughout their surveillance period. Five patients (42%) had sonographic abnormalities; four were identified on initial US and one was identified greater than one month after birth. Germinal matrix hemorrhage grades 1 (n=2), 2 (n=1), 3 with cerebellar hemorrhagic injury (n=1) and 4 (n=1) were observed. Examples of germinal matrix distributed more widely than expected in older premature infants were also identified. Microvascular imaging was found to aid with visualizing normal anatomy and differentiating certain pathologies from adjacent structures.
Conclusions: Periviable premature neonates demonstrated head US pathology primarily related to germinal matrix hemorrhage. An understanding of the unique distribution of germinal matrix in this population is important, for which microvascular imaging provides additional detail and may have use as a diagnostic aid.