Who is most likely to develop pyloric stenosis?

Pyloric stenosis is a condition that involves the narrowing of the pylorus, the opening from the stomach into the small intestine, leading to obstruction. This condition primarily affects infants, and its typical presentation occurs between the ages of 2 weeks and 8 months, with a peak incidence between 3 to 12 weeks of age.

The likelihood of developing pyloric stenosis is significantly higher in males compared to females, with reports indicating a ratio of approximately 3:1. The age and gender of the infant are vital in determining the probability of developing this condition.

The correct answer identifies a 5-week-old male as most likely to develop pyloric stenosis because he falls into the most common age range for onset and the male gender predisposes him to the condition. In contrast, while a 12-week-old male is also at risk, he is slightly older than the most common age of presentation. A 5-year-old female does not fit the typical demographic, as pyloric stenosis generally resolves or is addressed before this age. Similarly, a newborn female is less likely to be affected; while females can and do develop the condition, the incidence in males remains significantly higher, especially within the first few months of life.