Hypertrophic pyloric stenosis: determination of muscle dimensions by ultrasound.

To evaluate the usefulness of ultrasound in hypertrophic pyloric stenosis (HPS) and to analyse the correlation between the dimensions of the pyloric muscle and the age and the weight of the child, 34 children with suspected HPS and 34 controls were examined. An overlap between the dimensions of the pyloric muscle in the HPS group and in the controls stresses the need to assess the muscle length, the muscle diameter, and the muscle wall thickness in establishing the sonographic diagnosis of HPS. We found the following criteria useful: muscle length greater than or equal to 19 mm, muscle diameter greater than or equal to 10 mm, and muscle wall thickness greater than or equal to 4 mm. The results did not confirm previous reports of increasing dimensions of the pyloric muscle with age and weight.