The author analysed the clinical features and management of 91 young infants who were undergoing pyloromyotomy by author for IHPS from January 1981 through December 1997 at Ewha Womans University Hospital. The findings were compared between the former(1981-1990) and the latter period(1991-1997).

Among the total 91 cases, 42 cases were included into the former and 49 cases were the latter period. There has been no difference in sex ratio, birth rank, and age at time of admission between the former and the latter period. The percentage of patients breastfed decreased from 23.8% to 0. And the percentage of patients with alkalosis decreased from 54.8% to 30.6%, hypochloremia from 57.1% to 39.6%, and hypokalemia from 45.2% to 29.2% under the influence of increasing the incidence of early diagnosis. The number of patients with palpable pyloric mass by palpation of the abdomen decreased from 83.3% to 71.4%. And the use of upper gastrointestinal series only as diagnostic test decreased from 71.4% to 18.4%, ultrasonography increased from 11.9% to 46.9%, and both increased from 11.9% to 34.7%. There was no specific postoperative complication during the latter period, and the postoperative hospital stay decreased from 7.1±1.5 days to 4.5±0.7 days.

In conclusion, the increasing use of ultrasonography as diagnositic tool enabled the early diagnosis of infantile hypertrophic pyloric stenosis before appearing the disturbed fluidelectrolyte balance of the body. Although the signification decrease of the postoperative hospital stay and complications in the latter period, there has been less change in areas controlled by other specilaties.