The improved ultrasound diagnosis of hypertrophic pyloric stenosis.

A prospective study of ultrasound in the diagnosis of idiopathic hypertrophic pyloric stenosis (IHPS) in 200 consecutive infants with persistent vomiting is reported. The criteria evaluated include measurements of the pyloric diameter, muscle thickness and canal length, and observing the function of the pylorus and gastric peristalsis in real-time. Using these ultrasonic criteria, the infants studied were assessed as 112 with IHPS and 88 normals. All the infants were followed up, and the method was 100% accurate, with no false positive or negative results. The statistics of the static measurements are included and show that the canal length is the only precise discriminator between a normal and an hypertrophied pylorus. The method is accurate, rapid and safe, allowing earlier diagnosis of IHPS. It should replace the barium meal in the evaluation of IHPS where the clinical diagnosis is in doubt.