What condition is often characterized by projectile vomiting and constant hunger in infants?

The condition characterized by projectile vomiting and constant hunger in infants is pyloric stenosis. This condition occurs when the pylorus, the opening from the stomach into the small intestine, becomes narrowed. This narrowing prevents the passage of food from the stomach into the intestines, which leads to symptoms like projectile vomiting that occurs shortly after feeding. Infants with pyloric stenosis often exhibit an increased appetite, as they are unable to retain food in the stomach and quickly become hungry again after vomiting. This combination of projectile vomiting and persistent hunger is a classic sign that helps clinicians make a diagnosis.

In contrast, Hirschsprung's disease primarily involves an absence of nerve cells in parts of the colon, leading to issues with stool passage and constipation rather than vomiting. Enuresis refers to involuntary urination, typically occurring in older children rather than infants, and is unrelated to vomiting or feeding issues. Intussusception occurs when a part of the intestine folds into another section, leading to obstruction and can manifest with abdominal pain and potentially vomiting, but the vomiting is not typically projectile, and constant hunger is not a primary symptom. Each of these conditions has distinct clinical features that help differentiate them from pyloric stenosis.