What is the best imaging study for a newborn presenting with gastric distention and bilious emesis?

In a newborn presenting with gastric distension and bilious emesis, the most appropriate imaging study is an abdominal X-ray. This condition often raises concern for potential gastrointestinal obstructions, such as a duodenal atresia or volvulus. An abdominal X-ray is beneficial in this scenario because it can quickly visualize the presence of air-fluid levels, distended loops of bowel, and signs of obstruction.

Additionally, obtaining an X-ray is a rapid and non-invasive procedure, making it particularly suitable for a vulnerable population like neonates. It allows clinicians to assess for potential causes of the symptoms and determine if immediate surgical intervention or further imaging is warranted.

While there are other imaging modalities available, such as ultrasound and CT scans, they have limitations in this specific clinical context. Ultrasound can be useful but may not provide the comprehensive information needed for diagnosing a complete intestinal obstruction in this age group. CT scans are typically avoided in neonates due to the high radiation exposure, and MRI is generally not used for acute abdominal cases in newborns due to its complexity and length of time required for the procedure.