What symptom might lead to the diagnosis of pyloric stenosis in infants?

Non-bilious vomiting is a key symptom that can lead to the diagnosis of pyloric stenosis in infants. This condition involves the narrowing of the pylorus, which is the opening from the stomach into the small intestine, leading to gastric outlet obstruction. As a result, infants with pyloric stenosis frequently experience projectile vomiting, which may be severe and often occurs shortly after feeding. The vomitus in this case is non-bilious because the obstruction prevents the passage of bile into the stomach.

Understanding the characteristics of this vomiting is crucial. In pyloric stenosis, the vomit may appear curdled milk or be without any bile, differentiating it from other gastrointestinal issues that often produce bilious vomit. The age of the infant, typically between two to eight weeks, along with the pattern of vomiting, may further support the diagnosis. Besides the vomiting, this condition may also lead to dehydration and electrolyte imbalances, but these symptoms are secondary and not the initial indicators for the diagnosis of pyloric stenosis.