Diagnosis of colorectal carcinoma--is colonoscopy superior to barium enema?

From January 1984 to December 1987, 520 pathologically proved cases of colorectal carcinomas were treated in Mackay Memorial Hospital - 272 (52.5%) were male and 248 (47.7%) were female. The distribution of carcinomas in the colorectum were caecum 27 (5%), ascending colon 49 (9.1%), transverse colon 70 (13%), descending colon 41 (7.6%), sigmoid colon 93 (17.3%), rectosigmoid colon 19 (3.5%) and rectum 239 (44.4%). Fourteen cases (3.3%) had double carcinomas. When 334 barium enema examinations (210 single contrast, 124 double contrast) and 207 colonoscopies were done, false negative results were found in 31 (14.76%) single contrast barium enema (BaE-S) and eight (6.45%) in double contrast barium enema (BaE-D) examinations, and 7 (3.38%) colonoscopic examinations failed to demonstrate cancer lesions because of incomplete examinations from technical problems. False negative in BaE were mostly due to failure to recognize or misinterpret the lesions especially in the rectum. Colonoscopy is significantly more accurate than BaE-S but not with BaE-D. BaE especially BaE-D can be complementary to colonoscopy in a nearly obstructing colon. Direct biopsy of the lesion makes colonoscopy more useful than BaE. Complete removal of a malignant polyp turns colonoscopy into a therapeutic modality. However, a well-trained endoscopist is essential in making colonoscopy a less suffering and more accurate examination. In a symptomatic patient, a confirmatory examination is always needed after positive BaE finding. Sometimes this can be avoided by having colonoscopy done first.