Rapid Review: Pyloric Stenosis

Reviewed March 2024

Pyloric Stenosis

• 2–8 weeks of age, boys > girls
• Nonbilious projectile vomiting after feeding, early satiety
• Clinical: dehydration, RUQ olive-like mass 
• Labs: hypochloremic hypokalemic metabolic alkalosis
• Dx: ultrasound or UGI series (string sign)
• Tx: surgery, fluid & electrolyte replacement

Sample question:

A 3-week-old boy presents with two days of nonbilious projectile vomiting. Examination reveals a mass in the infant’s right upper quadrant. On a barium upper GI series report, the radiologist states a string sign is present. Which of the following is this infant at greatest risk of developing?