A 6-week-old male infant was brought to the pediatric clinic by his parents with concerns about frequent vomiting after feeding. The parents reported that the vomiting had gradually worsened over the past two weeks and had become more forceful, often projectile in nature. They noted that the baby had been irritable and seemed hungry after vomiting but was not gaining weight as expected.

The infant was born full-term with no complications during pregnancy or delivery. He had been exclusively breastfed and initially fed well. However, over the last two weeks, the vomiting episodes had become more frequent, typically occurring 20-30 minutes after feeding. The parents also mentioned fewer wet diapers than usual.

On physical examination, the baby appeared dehydrated with dry mucous membranes and slightly sunken fontanelles. His weight was in the 10th percentile, indicating failure to thrive. During the abdominal exam, a firm, olive-sized mass was palpated in the upper right quadrant of the abdomen, consistent with hypertrophy of the pylorus. Visible peristaltic waves were observed moving from left to right across the abdomen after feeding.

An abdominal ultrasound was ordered, which confirmed the diagnosis of pyloric stenosis, revealing a thickened and elongated pylorus. Blood tests showed hypochloremic metabolic alkalosis, a common finding due to the loss of gastric acid through vomiting.

The infant was admitted to the pediatric surgical unit and underwent successful pyloromyotomy. Postoperatively, he was gradually reintroduced to feeding, and within a few days, his symptoms had resolved. He was discharged home with follow-up scheduled to monitor growth and recovery.