What is the diagnostic test of choice for pyloric stenosis?

The diagnostic test of choice for pyloric stenosis is ultrasound. This choice is due to the ultrasound's ability to effectively visualize the thickened pyloric muscle, which is characteristic of pyloric stenosis. The ultrasound is non-invasive, does not involve ionizing radiation, and provides real-time images that are helpful in assessing the condition of the pylorus. It can demonstrate the classic findings, such as the "string sign" or "target sign," that are indicative of this condition.

In the context of pyloric stenosis diagnosis, other imaging modalities like CT scans are usually reserved for cases where there is a need to evaluate for complications or differential diagnoses and are not first-line options due to radiation exposure and cost. X-rays may show signs of distal obstruction but are not specific for pyloric stenosis. Endoscopy is not typically used for diagnosing this condition, as it is more invasive and not suited for visualizing the pylorus in the same detailed manner as an ultrasound.

Overall, ultrasound stands out as the safest, most accessible, and most effective method to confirm a diagnosis of pyloric stenosis in pediatric patients.