- Etiology: hypertrophy of pylorus muscle
- AXR: caterpillar sign due to hyperperistalsis
- US: pyloric muscle > 3.5 mm thick, pyloric channel > 17 mm long
- UGI: antrum + duodenal bulb deformity on upper GI: antral shouldering + pyloric beak / teat + tram track through pylorus
- DDX: prostaglandin E induced gastritis
