Infantile hypertrophic pyloric stenosis--diagnosis from the pyloric muscle index.

Measurements of pyloric length, diameter and muscle thickness were made from ultrasound images of 39 babies, 21 of whom were subsequently found at operation to have infantile hypertrophic pyloric stenosis. From these measurements, the volume of pyloric muscle in cm3 was estimated for each case and divided by the body weight in kilograms. The resulting pyloric muscle index proved to be a much more reliable guide to the diagnosis of pyloric stenosis than any of the individual measurements or the volume estimation alone.