Subdural collections in the neonatal ICU: Assessment using high frequency sonography

Abstract

Background

Subdural collections (SDC) in the neonate are most often diagnosed on CT and MR as birth related subdural hematoma. With the use of high frequency linear ultrasound (US) transducers, SDC have been seen with increased frequency by US in our NICU population.

Objective

The aim is to determine the prevalence of SDC on US in our NICU population and to assess whether changes in US transducer frequency effects detection.

Materials/methods

A retrospective review was conducted of head US in our NICU between August 2020 and March 2021. All scans were done using the anterior fontanelle approach. Included exams had cine clips with 1) full brain field of view (FOV) with linear 2–9 MHz transducer, and 2) superficial FOV with either linear 2–9 or 6–24 MHz transducer. Images were assessed for presence of SDC and if present echogenicity of the SDC relative to the subarachnoid fluid.

Results

142 US exams met inclusion criteria. SDC were identified in 10 patients, on 15 studies. For patients with SDC, median gestational age at birth was 31.3 weeks (versus 34.4 weeks in patients without SDC). SDC were only identified on superficial FOV cine clips performed with the 6–24 MHz transducer, and all were anechoic. Earlier gestational age and thrombocytopenia were associated with SDC.

Conclusion

Small anechoic subdural collections can be visualized in head US exams in NICU patients; however, their detection is highly dependent on the use of very high frequency linear transducer with small FOV imaging.