Randomized Controlled Trial of Fellow Impact on Detection

Randomized Controlled Trial of Fellow Impact on Detection

Douglas K. Rex, MD, FASGE, reviewing Facciorusso A, et al. Gastrointest Endosc 2020 May 17.

There is widespread acceptance of a second-observer effect in improving adenoma detection in colonoscopy and general acceptance that this effect extends, in some regard, to GI fellows. 

In a randomized trial that was conducted at 4 hospitals in Italy and included 812 patients, fellow participation in colonoscopy was associated with an increase in the adenoma detection rate (ADR) from 37.1% to 44.8% and an increase in adenomas per colonoscopy from 0.53 to 0.65 (P<.001). Rates of advanced adenomas and sessile serrated lesions were not different between the groups. In the subgroup of fellows with >150 examinations, ADR was higher at 49.5% versus 39.7% in fellows with less training. Similarly, the gain in ADR for fellows compared to attending physicians only occurred with the more experienced fellows. Withdrawal time was longer with fellow involvement (10 minutes vs 7 minutes; P=.12), and total colonoscopy duration was longer (25 minutes vs 18 minutes; P=.05).

Douglas K. Rex, MD, FASGE


It’s remarkable that the 3-minute difference in withdrawal time with fellow involvement did not reach significance in a study of this size. The standard deviation around withdrawal times must have been very large. The authors tried to minimize this effect, but it’s possible that longer withdrawal times and even longer insertion times (polyps are detected on insertion) contributed to the ADR differences.

However, the literature does indicate that having additional observers increases polyp detection during colonoscopy.

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


Facciorusso A, Buccino VR, Tonti P, et al. Impact of fellow participation on colon adenoma detection rates: a multicenter randomized trial. Gastrointest Endosc 2020 May 17. (Epub ahead of print) (https://doi.org/10.1016/j.gie.2020.05.015)

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