The nurse is caring for a 5-week-old infant presenting with a history of projectile vomiting after feedings. Which additional finding should the nurse expect to assess?

In a 5-week-old infant presenting with a history of projectile vomiting after feedings, the nurse should expect to assess an olive-size mass in the epigastric area. This finding is consistent with pyloric stenosis, a condition in which the muscle at the bottom of the stomach that controls the flow of food into the small intestine becomes thickened and narrowed. Rebound tenderness in the left lower abdominal quadrant, stool that consists of mucus and blood, and frequent burping accompanied by poor feeding are not typically associated with pyloric stenosis.