High frequency ultrasounds may be used to identify abnormal fluid buildups surrounding the brains of neonates, according to results recently published in Pediatric Radiology.
While not always the cause, fluid in the brain can be caused by fetal and neonatal alloimmune thrombocytopenia (FNAIT).
Subdural collections (SDC), which the authors assessed in this study, refer to fluids that accumulate in the space just inside the outer membrane of the brain. This may include cerebrospinal fluid or blood. SDC has several potential causes including head injury or bleeding disorders such as thrombocytopenia.
Typically, magnetic resonance imaging (MRI) or computed tomography (CT) scans are used to evaluate for neonatal SDC. However, ultrasounds are being more commonly used in this setting.
“Ultrasound is a low cost, well tolerated modality for the assessment of the brain in neonates,” the authors wrote. “As the technology improves, with higher transducer frequency and increased resolution, we are afforded better anatomic detail in our images, making previously poorly or undetectable findings visible.”
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In their study, the authors analyzed 142 head ultrasound exams from 89 infants admitted to the neonatal intensive care unit between August 2020 and March 2021. In 87 of these exams, a high frequency transducer was utilized.
While none of the low frequency scans showed evidence of SDC, 10 patients with SDC were identified in 15 high frequency scans. These patients had a median gestational age of 31.3 weeks at birth, compared to a gestational age of 34.4 weeks among those without SDC. While 70% of infants with SDC had thrombocytopenia, only 32% of those without SDC had thrombocytopenia.
Of the 10 infants with evidence of SDC on initial ultrasound, two had follow-up exams at 30 and 31 days of life, respectively, neither of which showed SDC. Notably, of the 5 patients who also received an MRI, none of the scans identified the SDC that was detected by ultrasound.
Based on these findings, the authors suggest that future research be conducted to directly compare ultrasound findings with MRI and CT scans. Additionally, more studies are needed to determine the precise content of the fluid accumulations.
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