Imaging Case of the Week 298 Answer

The supine abdominal x-ray shows distension of the stomach giving rise to the ‘single bubble’ appearance. Gas can also be seen in the small bowel and rectum.

The infant had an ultrasound scan of the abdomen due to a high index of clinical suspicion for hypertrophic pyloric stenosis (HPS). This diagnostic scan confirmed pyloric stenosis.

Plain abdominal x-ray is not a confirmatory test to diagnose HPS; an abdominal x-ray, if undertaken, may indicate a dilated stomach with scanty gas in the small bowel. The superior diagnostic test to diagnose HPS is an ultrasound.

This particular patient makes for an unusual case as the x-ray indicates a good amount of gas in the small bowel, despite the ultrasound showing a near complete HPS!

Reference: Radiology Cases in Paediatric Emergency Medicine, Univ. Hawaii