Congenital hypertrophic pyloric stenosis is considered a type of gastric outlet obstruction. It is common in males. It is usually diagnosed if the length is more than 15 mm, width more than 7 mm and muscle thickness more than 3 mm (with variance between studies).

The antral nipple sign refers to redundant pyloric mucosa protruding into the gastric antrum. The cervix sign of pyloric stenosis describes indentation of the pylorus into the fluid-filled antrum. The target sign of pyloric stenosis is a sign seen due to hypertrophied hypoechoic muscle surrounding echogenic mucosa.