A nurse is caring for a male infant who has a palpable mass in the upper right quadrant and stools mixed with blood and mucus. The nurse should recognize that which of the following diagnoses is associated with these findings?

Choice A reason: Oral rehydration solution (ORS) is the best fluid for a child with acute gastroenteritis, as it contains the optimal balance of electrolytes and glucose to prevent dehydration and restore fluid balance. ORS is recommended by the World Health Organization (WHO) and the American Academy of Pediatrics (AAP) for the management of diarrhea in children.

Choice B reason: Water is not a good fluid for a child with acute gastroenteritis, as it does not contain any electrolytes or glucose and can dilute the blood sodium level, leading to hyponatremia. Water can also increase the osmotic load in the intestines and worsen diarrhea.

Choice C reason: Broth is not a good fluid for a child with acute gastroenteritis, as it is high in sodium and can cause hypernatremia and dehydration. Broth can also irritate the intestinal mucosa and increase diarrhea.

Choice D reason: Diluted apple juice is not a good fluid for a child with acute gastroenteritis, as it is high in fructose and can cause osmotic diarrhea. Apple juice can also lower the blood pH and cause metabolic acidosis.

Choice A reason: Pyloric stenosis is a condition in which the muscle at the outlet of the stomach (the pylorus) becomes thickened and obstructs the passage of food into the small intestine. It usually occurs in infants between 2 and 8 weeks of age, and is more common in males. The main symptoms are projectile vomiting after feeding, dehydration, weight loss, and a palpable olive-shaped mass in the right upper quadrant of the abdomen.

Choice B reason: Gastroesophageal reflux is a condition in which the lower esophageal sphincter fails to close properly, allowing the stomach contents to flow back into the esophagus. It is common in infants, especially those who are bottle-fed, and usually resolves by 12 months of age. The main symptoms are regurgitation, spitting up, irritability, and poor weight gain.

Choice C reason: Celiac disease is a condition in which the immune system reacts to gluten, a protein found in wheat, barley, and rye, and damages the lining of the small intestine. It can affect people of any age, but is usually diagnosed in childhood. The main symptoms are diarrhea, abdominal pain, bloating, weight loss, and failure to thrive.

Choice D reason: Lactose intolerance is a condition in which the body lacks the enzyme lactase, which is needed to digest lactose, a sugar found in milk and dairy products. It can affect people of any age, but is more common in adults and certain ethnic groups. The main symptoms are diarrhea, gas, bloating, and abdominal cramps after consuming lactose-containing foods.