Plain abdominal radiography prior to barium enema: is it accurate? is it effective? is it necessary?

To asses the efficacy of plain abdominal X-ray prior to barium enema as a method of evaluating the results of bowel cleansing. The authors carried out an open, phase IV, uncontrolled, single center, cross-sectional, observational study of 150 volunteers who underwent plain abdominal radiography followed by barium enema in the ambulatory setting. In both procedures, the status of the bowel after cleansing was assessed (presence or absence of substantial residual fecal material that might make it difficult to rule out the presence of polypoid lesions measuring 1 cm or more). The purpose was to determine whether or not plain X-ray was capable of correctly predicting desirable or insufficient cleansing, using the barium enema findings as a reference. The data were employed to calculate the sensitivity, specificity and predictive values of plain radiography. Plain abdominal films predicted the degree of bowel cleanliness with a sensitivity of 96.22%, a specificity of 20. 45%, a rate of false negatives of 3.77%, a rate of false positives of 79.54%, a negative predictive value of 69.23%, a positive predictive value of 74.45% and an overall predictive value (or predictive accuracy) of 74%. Plain abdominal X-ray is inaccurate and of little value in the assessment of the results of bowel cleansing prior to barium enema. (Author) 6 refs