How many polyps are there?
BACKGROUND
Frequently, there is disagreement between consecutive endoscopies about the true number of mucosal lesions.


OBJECTIVE
To develop a simple means to estimate the total number of mucosal lesions and the number of lesions missed during consecutive endoscopies.


METHODS
Probability modeling of endoscopic outcomes.


METHODS
Subjects undergoing 2 consecutive endoscopies.


METHODS
Total number of mucosal lesions and number of missed lesions.


RESULTS
If a represents the number of lesions seen by the first endoscopist, b the number of lesions seen by the second endoscopist, and c the number of identical lesions seen by both, then the total number of lesions is given by T = ab/c, and the number of lesions missed by both is given by M = (a - c)(b - c)/c. The estimated numbers for all lesions and for missed lesions increase as the number of identical lesions seen by both endoscopists decreases. If the number of identical lesions seen by both endoscopists matches the number of lesions found by any one endoscopist, the numbers of estimated and found polyps are identical and the number of missed polyps equals zero.


CONCLUSIONS
The analysis assumes that both endoscopists work independently of each other and are equally qualified. The formulas also fail to account for varying characteristics of similar lesions.


CONCLUSIONS
The analysis presents a simple, unbiased means to estimate the total number of mucosal lesions if 2 consecutive endoscopies yield slightly conflicting results.
Sonnenberg
Amnon
A
Portland VA Medical Center and the Oregon Health & Science University, Portland, Oregon 97239, USA.
D003111:Colonic Polyps / Q000175:diagnosis; D016145:Endoscopy, Digestive System; D005767:Gastrointestinal Diseases / Q000175:diagnosis*; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology*; D015233:Models, Statistical