Since the 1950s, several large pediatric centers have used hydrostatic reduction with barium under fluoroscopic control as the treatment method of choice for ileocolic intussusception and have adopted rigid criteria for its management. One such rule has been that in order for an intussusception to be completely reduced, there must be adequate reflux of barium into the distal ileum. If this did not occur, it was assumed that the ileocolic intussusception had not been reduced, and the infant or child was taken straight to the operating room for laparotomy and surgical treatment. However, 10% of such intussusceptions were found to have reduced spontaneously. Needless to say, nonoperative management reduces morbidity and shortens hospitalization. From October 1985 through March 1991, 503 air contrast colon studies for suspected intussusception were performed on infants and children aged 2 days to 13 years (average, 16.8 months); 262 (52%) were normal, and 241 had an intussusception, 196 (81%) of which were reduced. The remaining 45 were operated on. In three patients (4 months to 2 years of age) the air enema reduced the intussusception from the colon without terminal ileum filling, but they all became asymptomatic immediately. For this reason they were not operated on; they were admitted and observed for 24 to 48 hours. Two of the three had recurrence of abdominal pain the next morning, but results of repeat air enemas were all normal (no intussusception observed, and normal terminal ileum filling).(ABSTRACT TRUNCATED AT 250 WORDS)