Pyloric size in normal infants and in infants suspected of having hypertrophic pyloric stenosis.

Pyloric muscle thickness (PMT) and pyloric diameter (PD) were determined by sonography in 92 healthy infants aged 8 to 70 days. PMT and PD measured median 2.0 mm and 10.0 mm. There was a significant correlation between the pyloric dimensions and the infant's age, p < 0.02 and p < 0.00001 for PMT and PD, respectively. In 26 infants with an initial diagnosis of hypertrophic pyloric stenosis (HPS), but with a final diagnosis of no HPS the mean figures were 2.4 and 11.0 mm, and in 21 infants with HPS, confirmed at surgery, the figures were 4.0 and 14.0. The pyloric dimensions in the 3 groups differed significantly. The larger-than-normal pyloric dimensions in the "no HPS" group suggest that some of these patients suffered from milder degrees of HPS.