In cases of neonatal bilious emesis suggesting bowel obstruction, what is the first imaging step typically performed?

In cases of neonatal bilious emesis that suggests bowel obstruction, the first imaging step typically performed is a plain abdominal X-ray. This choice is guided by the need for a quick and non-invasive way to evaluate the gastrointestinal tract for signs of obstruction, such as dilated loops of bowel, air-fluid levels, or free air indicating perforation.

A plain abdominal X-ray is particularly useful in neonates because it can provide immediate insights into the presence of bowel obstruction. It is also widely available and can be performed quickly, which is crucial in emergency situations where timely intervention may be necessary to avoid complications.

Other imaging modalities have specific uses but are generally not the initial step in this context. A contrast enema may be used later to assess for specific types of obstruction, like Hirschsprung disease or to differentiate between other potential conditions, but it is not as immediate as an X-ray. A CT scan is more detailed and can provide extensive information, but it involves higher radiation exposure and is not typically used in neonates as a first-line approach. Ultrasound can also be useful, particularly for conditions like intussusception, but it is usually not the first step when there is a suspicion of a more generalized bowel obstruction. Therefore, the plain abdominal