Pyloric stenosis: a postoperative ultrasonic study.

Six infants with hypertrophic pyloric stenosis and 20 control infants were studied ultrasonically on four occasions during the first year of life. At each examination the total diameter and muscle wall thickness of the pylorus were measured. Initially the pylorus was significantly (P less than 0.05) larger in the hypertrophic pyloric stenosis group but returned to normal values by 6 months postoperation. The control group showed a small increase in size of the pylorus over the 12 month period.