The pylorus in infancy: overall sonographic assessment.

A prospective ultrasonic evaluation of the pylorus was performed in two groups of infants, a control group and a group of infants clinically suspected of having hypertrophic pyloric stenosis (HPS). The mean pyloric length in the hypertrophied condition was 84% longer than the mean length in the normal. The mean and standard deviation (sd) for the transverse diameter and pyloric wall thickness in the normals were 7.45 +/- 2.2 mm and 2.3 +/- 0.7 mm respectively, while the corresponding measurements for the mean and sd in HPS were 13.4 +/- 1.6 mm and 4.5 +/- 0.9 mm. In most of the HPS cases the known morphological changes of the antro-pyloric region such as: impingement on the fluid filled antrum, pre-pyloric antral thickening, extension of fluid into the proximal portion of the pyloric canal and the angle formed between antral peristaltic wave and pyloric mass, were observed. Detection of these changes furnished further criteria for highly accurate diagnosis of HPS even of borderline cases.