Colonoscopy: As Good as Gold?

But al thing which that shineth as the gold

Nis nat gold, as that I have herd it told

–Geoffrey Chaucer, Canterbury Tales (1387)

All that glitters is not gold;

Often have you heard that told

–William Shakespeare, Merchant of Venice (1596–1597)

As good as gold …

–Charles Dickens, A Christmas Carol (1843)

Although William Shakespeare's reputation may be slightly tarnished by the knowledge that he probably borrowed from Chaucer, he is, nevertheless, the bard against whom we compare all others. In gastroenterology, it has been a foregone conclusion that colonoscopy can provide the most accurate examination of the colon, and it is the gold standard against which we judge other tests. With the increasing use of colonoscopy in colon cancer screening as a primary test or a test after a positive screening result with fecal occult blood test, sigmoidoscopy, computed tomography colonography, or fecal DNA testing, knowing the true accuracy of colonoscopy takes on even greater importance.

In previous studies of colonoscopy accuracy (1, 2), patients had 2 colonoscopy examinations performed by different endoscopists (gold vs. gold). Colonoscopy seldom missed polyps greater than 1 cm (miss rate, 0% to 6%). These studies are biased toward agreement between the first and second colonoscopy—and therefore toward overestimating sensitivity and specificity—because factors leading to a miss on the first examination (such as a polyp hiding behind a fold) are likely to be similar during the second examination. Pickhardt and colleagues (3, 4) cleverly evaluated the sensitivity and specificity of optical colonoscopy (OC) by performing virtual colonoscopy (VC) followed by OC. After the endoscopist examined each segment of the colon, the results of VC were revealed. If …