A comparison of colonoscopy and roentgenography for detecting polypoid lesions of the colon.

This study compares the effectiveness of the roentgen and colonoscopic examination of the colon for detecting polypoid lesions. We evaluated the findings in 64 patients with suspected or known polypoid lesions who received the same colon cleansing regimen for both examinations, and were studied by examiners of similar expertise. As in other studies, the endoscopist had the advantage of knowing the roentgen findings, and the colonoscopic findings were often taken to indicate whether or not a lesion was present. In about half the patients, however, a second roentgen examination, repeat colonoscopy, or surgical specimen provided additional information for scoring. For example, a filling defect of the same size and location on two roentgen examinations, but not demonstrated at colonoscopy was scored as a false negative colonoscopic finding. The study results indicate that 54% of small polyps less than or equal to 0.9 cm in size were missed on roentgen examination, whereas no proven misses for lesions of this size were shown for colonoscopy. This absence of colonoscopic false-negative findings for small polyps, however, may be partially explained by a relative insensitivity of the roentgen method. For larger lesions greater than or equal to 1.0 cm in size the miss-rate for the two examinations was similar: 15% for roentgen examination and 12% for colonoscopy. We conclude: (1) Colonoscopy is a more sensitive method than roentgen examination for detecting small polyps of the colon, and (2) Performance of the two examinations may be comparable for demonstrating lesions 1.0 cm or larger in size.