A 2-month-old infant is brought in for frequent spit-ups aft…

A 2-month-old infant is brought in for frequent spit-ups after feeding. The spit up is non-bloody and non-bilious. The baby is otherwise healthy, gaining weight appropriately, has no signs of respiratory distress or irritability, and has appropriate wet diapers with yellow/seedy bowel movements. What is the most appropriate next step in management?

A 4-week-old infant presents with projectile, non-bilious vo…

A 4-week-old infant presents with projectile, non-bilious vomiting occurring after every feed. The infant remains hungry and continues to feed eagerly. On examination, you palpate an “olive-shaped” mass in the right upper quadrant of the abdomen. Which of the following is the most likely diagnosis?