A baby is admitted into the hospital with a history of projectile vomiting after each feeding. On examination, it is found that the pyloric sphincter is thickened and does not open readily. Because of the baby's loss of gastric juice, his blood probably indicates:

1. A

   Acidosis

2. B

   Leukocytosis

3. C

   Alkalosis

4. D

   An excessively low pH

Appeared in: OSSSC Nursing Officer-2023

Explanation

• The infant's symptoms (projectile vomiting, thickened pyloric sphincter) are classic for hypertrophic pyloric stenosis.
• Persistent vomiting causes a significant loss of gastric juice, which contains hydrochloric acid (HCl).
• The loss of hydrogen ions (H+) and chloride (Cl-) from the stomach leads to a compensatory increase in serum bicarbonate (HCO₃⁻) by the kidneys, resulting in hypochloremic metabolic alkalosis.

Why Other Options Were Wrong

• Option A: Acidosis results from a loss of base (bicarbonate) or an accumulation of acid. Vomiting causes a loss of acid, leading to the opposite condition, alkalosis.
• Option B: Leukocytosis is an elevated white blood cell count, which is a sign of infection or a significant inflammatory response. It is not a direct metabolic consequence of losing gastric acid.
• Option D: An excessively low pH is the definition of acidosis. The loss of stomach acid causes the blood pH to rise (become more alkaline), not fall.

Related Visual

Clinical Relevance

• Nursing practice connection: Safe nursing care depends on performing Metabolic alkalosis secondary to hypertrophic pyloric stenosis in the correct sequence, documenting the action clearly, and monitoring for the expected response.
• Recognizing the link between projectile vomiting and metabolic alkalosis is crucial for nurses, as it indicates pyloric stenosis and the need for urgent fluid and electrolyte correction.
• Pre-operative nursing care focuses on correcting dehydration, hypokalemia, and alkalosis with intravenous fluids (e.g., normal saline with added potassium) to ensure the infant is stable for surgery (pyloromyotomy).
• What if? If the infant presented with severe, watery diarrhea instead of vomiting, the primary loss would be bicarbonate-rich intestinal fluid, leading to metabolic acidosis, not alkalosis.

How to Approach the Question

• Identify the clinical condition from the signs: Projectile vomiting after feeding in a baby + thickened pyloric sphincter = classic hypertrophic pyloric stenosis.
• Determine the substance being lost: The stem specifies 'loss of gastric juice'.
• Recall the composition of gastric juice: It is highly acidic due to hydrochloric acid (HCl).
• Apply acid-base principles: Losing a large volume of acid (H+ ions) from the body makes the blood less acidic, or more alkaline.
• Match the principle to the options: 'Alkalosis' is the medical term for this state. 'Acidosis' and 'low pH' are the opposite. 'Leukocytosis' is unrelated to acid-base balance.

Concept Tested & Keywords

• Concept Tested: Metabolic alkalosis secondary to hypertrophic pyloric stenosis
• Stem keywords: baby, projectile vomiting, pyloric sphincter thickened, loss of gastric juice
• Lead-in keywords: probably indicates
• Clinical cues: Projectile vomiting in an infant is a hallmark sign of pyloric stenosis.
• Clinical cues: Loss of gastric juice directly implies loss of stomach acid (HCl).

Question ID

QbB1f96Ovxy7DX4r-X29mh

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 58-60

E6 Text Book Of Pediatric Nursing 3rd Panchali Pal — Part 2 (pp 239-476 of 713) p. 158-160

E6 Text Book Of Pediatric Nursing 3rd Panchali Pal — Part 3 (pp 477-702 of 713) p. 61-63