Of the historical and physical exam variables listed in Appendix 1, four were noted to be significantly more common in constipated patients. The discriminant function analysis identified one single variable, stool present on rectal exam, as the best discriminator between patients with and without constipation. All 21 patients were identified by the ED physician as having a diagnosis other than constipation prior to radiographic evaluation. Stool habits are age dependent. Infants normally have more than four stools per day during the first week of life and the frequency decreases to two per day by 4 years of age.
Most school aged children pass at least three stools per week, with an average of one stool per day.
The diagnosis of constipation is often made by clinicians based on this historical criteria. In our study however, historical information did not reliably distinguish patients with radiographically proven constipation from those without constipation. Use of this historical criteria in our study significantly underestimated the incidence of radiographically proven constipation. Multiple physical examination variables were analyzed independently and as a model including rebound, rigidity, guarding, tympanic bowel sounds and location of abdominal tenderness. Although there was a difference in these variables between the radiographically constipated and nonconstipated groups, it was not statistically significant.