Snapshot A 6-week-old first-born baby boy presents with projectile vomiting after feedings over the last 24 hours. Mom says that he enjoys feeding, and even after he vomits, he appears eager and hungry. On physical exam, you palpate an olive-shaped mass in the epigastric region. Labs show blood pH 7.47 and potassium of 3.2 mmol/L. High Yield A newborn boy presents with projectile vomiting and is always hungry to eat more after vomiting. The vomit is non-bilious, and an olive shaped mass is palpable in the patients abdomen. The patient has been treated with erythromycin for an infection. login to view 4 more bullets Introduction Congenital hypertrophy of the pyloric sphincter Prevents stomach from emptying contents into intestinal tract login to view 1 more bullet Epidemiology 1:500 births Males > females More common in first-borns Uncommon in children > 6 months old, most common within first 12 weeks of life ETIOLOGY Risk factors login to view 2 more bullets Associated with transesophageal fistulas Presentation Symptoms login to view 9 more bullets Physical exam login to view 4 more bullets IMAGING Barium studies login to view 2 more bullets Ultrasound login to view 1 more bullet STUDIES Electrolytes login to view 3 more bullets Differential Hiatal hernia, duodenal atresia, volvulus, meconium ileus, GERD, gastroenteritis, tracheoesophageal fistula Treatment Prevention login to view 1 more bullet Medical management login to view 5 more bullets Surgical intervention login to view 2 more bullets Complications Failure to thrive Prognosis Very good to excellent Surgery relieves symptoms and child is usually eating within hours of surgery