Pyloric stenosis affects males 4-5 times more often than females. It occurs between 4-8 weeks of life, and presents with non-bilious projectile vomiting. There may be a positive family history.

Ultrasound findings include:

• target sign: hypertrophied hypoechoic muscle surrounding echogenic mucosa
• elongated pylorus with thickened muscle
• cervix sign
• antral nipple sign
• exaggerated peristalsis
• failure of the pylorus to open