Clinical Presentation

A 4-week-old infant with projectile vomiting.

A longitudinal sonogram of the pyloric region demonstrates a fluid-distended stomach and a markedly elongated and thickened pylorus (arrows). During 10 minutes of sonographic monitoring, no emptying of the gastric contents through the pylorus was observed.

Differential Diagnosis

• Hypertrophic pyloric stenosis: A persistently elongated and thickened pyloric channel is typical of this disorder.

• Pylorospasm: The pylorus can appear elongated and thickened, but this appearance is transient, and antegrade emptying of the gastric contents will occur when the pylorus relaxes.

• Gastroesophageal reflux: