What is a characteristic symptom of pyloric stenosis in a newborn?

Pyloric stenosis is a condition in newborns where the pylorus, the opening from the stomach into the small intestine, becomes narrowed due to muscle thickening. This leads to a characteristic symptom of vomiting that is projectile and forceful. As the pyloric opening obstructs the passage of food from the stomach to the intestines, the infant vomits shortly after feeding, and this vomiting is often described as "projectile" due to its distance and force.

Projectile vomiting in pyloric stenosis typically occurs because the stomach is attempting to expel its contents forcefully due to the blockage, which is a key indicator of the condition and helps differentiate it from other types of gastrointestinal issues in infants. The timing of the vomiting, which usually happens shortly after feeding, and its intensity, set it apart as a classic symptom.

In addition, recognizing this symptom is crucial for timely diagnosis and management, as untreated pyloric stenosis can lead to dehydration and electrolyte imbalances in the newborn.