Reliability of routine double contrast examination of the large bowel: a prospective study of 2590 patients.

A total of 2590 consecutive patients referred for double contrast examination (DCE) of the large bowel were followed up radiographically, clinically, endoscopically, and histopathologically during a four year period. The patients were put into two groups on the basis of the presence or absence of radiographic evidence of colonic disease at the first--that is, index examination. By comparing the findings obtained at the index double contrast examination with those obtained during follow up, the sensitivity, specificity, and accuracy of the index double contrast examination were all calculated at 0.84. The predictive value of a positive report was 0.93 and that of a negative report 0.70. If, however, patients with normal double contrast examinations at the start of this series and not examined further during the follow up period were accepted as free from significant colonic disease, the predictive value of a negative report increased to 0.93. Double contrast examination is thus a reliable method for showing the presence of colonic lesions and therefore considerably helps the management of a given case.