What complication may arise as a result of vomiting in pyloric stenosis?

In pyloric stenosis, the hypertrophy of the pyloric muscle leads to gastric outlet obstruction, causing significant vomiting. The vomited contents consist primarily of gastric acid, which is rich in hydrochloric acid. When a patient vomits a substantial amount of this gastric content, there is a loss of hydrogen ions, leading to a decrease in the acidity of the blood.

This physiological response results in metabolic alkalosis, a condition characterized by an elevated blood pH and increased bicarbonate concentration. Consequently, metabolic alkalosis is a common complication of pyloric stenosis due to the gastric fluid losses through vomiting and the subsequent imbalance of electrolytes, particularly the loss of chloride ions, which further contributes to the alkalosis.

Understanding this mechanism highlights the importance of closely monitoring electrolyte levels and acid-base status in infants with pyloric stenosis and managing their hydration and nutrition appropriately.