Questions: A 2 week old who has previously nursed well has now begun vomiting immediately after feeding. Which condition presents with this behavior? Infantile hypertropic pyloric stenosis (IHPS) Distal intestinal obstruction syndrome (DIOS) Esophageal atresia (EA) Galactosemia

The answer is the first one: Infantile hypertrophic pyloric stenosis (IHPS).

Explanation for each option:

1. Infantile hypertrophic pyloric stenosis (IHPS): This condition typically presents in infants between 2 to 8 weeks of age. It is characterized by the thickening of the pyloric muscle, which leads to obstruction of the gastric outlet. The hallmark symptom is projectile vomiting immediately after feeding, which is non-bilious. This matches the description given in the question.

2. Distal intestinal obstruction syndrome (DIOS): This condition is more commonly associated with cystic fibrosis and typically presents later in life, not in a 2-week-old infant. Symptoms include abdominal pain and distension, and vomiting, but it is not specifically linked to immediate vomiting after feeding in a newborn.

3. Esophageal atresia (EA): This congenital condition is usually diagnosed shortly after birth because it prevents the infant from swallowing properly. Symptoms include drooling, choking, and respiratory distress during feeding, rather than vomiting immediately after feeding.

4. Galactosemia: This is a metabolic disorder that presents with symptoms such as jaundice, diarrhea, and failure to thrive when the infant is fed milk. Vomiting can occur, but it is not typically immediate after feeding and is accompanied by other systemic symptoms.

Summary: The condition that presents with a 2-week-old infant vomiting immediately after feeding is most consistent with Infantile hypertrophic pyloric stenosis (IHPS).