Positive Cologuard Test Makes for Longer Colonoscopy Time

Summary and Comment |
December 16, 2016

Positive Cologuard Test Makes for Longer Colonoscopy Time

  1. Douglas K. Rex, MD

Polyp detection was greater and withdrawal time longer when colonoscopists knew the patient had a positive stool DNA test.

  1. Douglas K. Rex, MD

Previous studies show that performing colonoscopy for a positive imaging test (computed tomographic colonography or double contrast barium enema) leads to a considerably longer colonoscopy procedure time, perhaps specifically because of difficulty or inability to find a false positive lesion.

In the current single-center study, U.S. investigators examined whether the indication of a positive multi-target stool DNA test (Cologuard) affected colonoscopy results and performance. They evaluated colonoscopies performed on 172 patients with known positive Cologuard test and 72 control patients with positive Cologuard test who underwent blinded colonoscopies (i.e., the endoscopist was unaware whether the test was positive or negative) as part of an earlier clinical trial.

In the unblinded colonoscopy group, detection of any polyp was 78% versus 60% in the blinded colonoscopy group (P<0.01), and the percentage of patients with any sessile serrated polyp or conventional adenoma was 70% versus 53%, respectively (P=0.01). Findings of slightly raised lesions in the right colon were more frequent in the unblinded versus the blinded group (40% vs. 9%; P<0.01). Medium withdrawal time was longer in the unblinded group (19 vs. 13 minutes; P=0.0001).


These data indicate that colonoscopist behavior probably changes when the indication for colonoscopy is a positive Cologuard test. It is likely that the same effect would be seen with positive fecal immunochemical test. Though additional study is warranted, this is an interesting way to derive a benefit from noninvasive screening. If this phenomenon is widespread for performance of colonoscopy with positive screening test, it would suggest reevaluation of the work associated with colonoscopy for positive screening test. Of course, we all know how difficult it is to achieve any increase in reimbursement for endoscopic procedures.

Note to readers: At the time NEJM Journal Watch reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

Editor Disclosures at Time of Publication

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant / Advisory board Covidien; Olympus Corporation America; Endo-Aid Ltd.; Endochoice; Boston Scientific; Paion AG; Ironwood Pharmaceuticals; Colonary Solutions; Novo Nordisk Inc.; Medscape Gastroenterology Grant / Research support: Braintree Laboratories Editorial boards World Journal of Gastroenterology; The Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; Gastroenterology & Hepatology; Expert Review of Gastroenterology & Hepatology; Medscape Gastroenterology; World Journal of Gastrointestinal Pharmacology and Therapeutics; Annals of Gastroenterology & Hepatology; World Journal of Gastrointestinal Oncology; Comparative Effectiveness Research; Journal of Anesthesia & Clinical Research; Gastroenterology; World Journal of Gastrointestinal Pathophysiology; Gastroenterology Research and Practice; GI & Hepatology News; Gastroenterology Report; Clinical Epidemiology Reviews; JSM Gastroenterology and Hepatology (associate editor); GI Journal Watch; Austin Journal of Gastroenterology; World Journal of Gastrointestinal Pharmacology & Therapeutics Leadership positions in professional societies American Society for Gastrointestinal Endoscopy (Councilor); US Multi-Society Task Forces (AGA, ACG, ASGE) (Chair)


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