A nurse working at a clinic speaks on the telephone with a parent of a 2-month-old infant. The parent tells the nurse that the infant has projectile vomiting followed by hunger after meals. Which of the following responses by the nurse is appropriate?

Choice A rationale Projectile vomiting followed by immediate hunger in a 2-month-old is a classic clinical manifestation of hypertrophic pyloric stenosis. This condition involves the thickening of the pyloric sphincter, which creates an obstruction at the gastric outlet. It requires prompt medical evaluation to prevent severe dehydration and electrolyte imbalances, such as hypokalemia or metabolic alkalosis. The infant needs an ultrasound and likely surgical intervention, so the nurse must prioritize an immediate in-person assessment by a provider. Choice B rationale While frequent burping is a standard intervention for normal gastroesophageal reflux or "spitting up," it will not resolve projectile vomiting caused by a physical obstruction. In pyloric stenosis, the vomiting is forceful and travels a significant distance because the stomach is trying to push milk past a narrowed opening. Suggesting more frequent burping delays necessary medical diagnosis and treatment for a potentially serious condition. The nurse must recognize that projectile vomiting is a red-flag symptom. Choice C rationale Switching formulas is a common strategy for infants with protein sensitivities or simple reflux, but it is inappropriate when projectile vomiting is reported. Pyloric stenosis is a structural problem, not a digestive or allergic reaction to the type of milk being consumed. Changing the formula would not allow the milk to pass through the hypertrophied pylorus. Advising a formula change wastes critical time and fails to address the underlying physiological cause of the infant's symptoms. Choice D rationale Although maintaining hydration is important, an oral rehydrating solution will likely be vomited back up just as the formula or breast milk was. If the infant has pyloric stenosis, the obstruction prevents significant oral intake from reaching the small intestine for absorption. Attempting home treatment with rehydration solutions is insufficient and dangerous if the child has a surgical obstruction. The priority is a clinical diagnosis so that intravenous fluids and surgical correction can be initiated.