Ultrasonographic follow-up of the healing process of medically treated hypertrophic pyloric stenosis.

In hypertrophic pyloric stenosis (HPS), prompt pyloromyotomy is, in general, the treatment of choice. There has been no information available as to the natural history of the pyloric tumour. We present four infants with medically treated HPS who were followed by sonography to observe the anatomical changes that occur with atropine sulfate. The initial change was shortening of the pyloric canal, followed by thinning of the muscular layer as clinical symptoms improved.