What condition is suspected in the infant presenting with projectile vomiting?

Projectile vomiting in infants is often indicative of pyloric stenosis, a condition where the pylorus, the opening from the stomach into the small intestine, becomes narrowed. This narrowing impedes the passage of food, leading to intense vomiting shortly after feeding. The characteristic nature of projectile vomiting—forceful and ejected from the mouth—along with the timing immediately after feeding, makes pyloric stenosis a likely diagnosis.

In the case of gastroesophageal reflux, while it does cause vomiting, it typically is not projectile and occurs more frequently in a regurgitant manner, which is different from the severe form seen in pyloric stenosis. Appendicitis generally presents with abdominal pain and is less common in infants, usually occurring in older children and adults. Infections can lead to vomiting, but these instances would often be accompanied by other systemic symptoms such as fever and lethargy, which tend to differ from the isolated projectile vomiting seen in pyloric stenosis. Therefore, the distinctive presentation of projectile vomiting strongly supports the diagnosis of pyloric stenosis.