What acid-base disturbance is commonly observed in cases of pyloric stenosis?

In cases of pyloric stenosis, the commonly observed acid-base disturbance is hypochloremic metabolic alkalosis. This condition occurs as a result of prolonged vomiting, which is typical in pyloric stenosis due to the obstruction at the pylorus that prevents normal passage of food from the stomach to the intestines.

When a patient vomits, hydrochloric acid (a component of gastric acid) is lost, leading to a decrease in chloride (hence the term hypochloremic). The loss of acid causes the blood's pH to increase, resulting in metabolic alkalosis. This condition is characterized by elevated bicarbonate levels and a high blood pH. The body attempts to compensate for this imbalance, but the persistent vomiting continues to exacerbate the alkalosis.

Understanding this condition is crucial, as it can impact the management and treatment of a child with pyloric stenosis. Recognizing the signs of hypochloremic metabolic alkalosis can guide the clinician in fluid and electrolyte management, as well as in planning the timing and approach to surgical intervention to correct the obstruction.