Certified Pediatric Nurse (CPN)

Which laboratory finding would a nurse expect in a child with pyloric stenosis?

1. PH 7.49, HCO3 29

2. PH 7.32, HCO3 29

3. PH 7.49, HCO3 18

4. PH 7.32, HCO3 18

The correct answer is: PH 7.49, HCO3 29

In pyloric stenosis, a significant laboratory finding is metabolic alkalosis due to the persistent vomiting of gastric contents, which are high in hydrochloric acid. This condition leads to an increased pH, and often results in an elevated bicarbonate level as the body attempts to compensate for the loss of acid. Choosing the correct answer involves recognizing the expected acid-base balance in such cases. A pH of 7.49 indicates alkalosis, and an HCO3 level of 29 signifies a compensatory mechanism by the body to retain bicarbonate in response to the loss of acid. The combination of these values suggests a metabolic alkalosis, which is characteristic of pyloric stenosis. The other options present different combinations of pH and bicarbonate that do not align with the metabolic alkalosis typically found in this condition. For example, a pH of 7.32 would indicate acidosis, which is not consistent with the pathophysiology of pyloric stenosis where vomiting leads to a retention of bicarbonate and a resultant increase in pH. Values that indicate a lower bicarbonate, such as 18, also do not reflect the metabolic compensation expected in this diagnosis. Thus, the selected choice accurately represents the laboratory findings that would be