Impact of fair bowel preparation quality on adenoma and serrated polyp detection: data from the New Hampshire colonoscopy registry by using a standardized preparation-quality rating

Gastrointest Endosc. 2014 Sep;80(3):463-70. doi: 10.1016/j.gie.2014.03.021. Epub 2014 May 10.


Background: The effect of colon preparation quality on adenoma detection rates (ADRs) is unclear, partly because of lack of uniform colon preparation ratings in prior studies. The New Hampshire Colonoscopy Registry collects detailed data from colonoscopies statewide, by using a uniform preparation quality scale after the endoscopist has cleaned the mucosa.

Objective: To compare the overall and proximal ADR and serrated polyp detection rates (SDR) in colonoscopies with differing levels of colon preparation quality.

Design: Cross-sectional.

Setting: New Hampshire statewide registry.

Patients: Patients undergoing colonoscopy.

Interventions: We examined colon preparation quality for 13,022 colonoscopies, graded by using specific descriptions provided to endoscopists. ADR and SDR are the number of colonoscopies with at least 1 adenoma or serrated polyp (excluding those in the rectum and/or sigmoid colon) detected divided by the total number of colonoscopies, for the preparation categories: optimal (excellent and/or good), fair, and poor.

Main outcome measurements: Overall/proximal ADR/SDR.

Results: The overall detection rates in examinations with fair colon preparation quality (SDR 8.9%; 95% confidence interval [CI], 7.4-10.7, ADR 27.1%; 95% CI, 24.6-30.0) were similar to rates observed in colonoscopies with optimal preparation quality (SDR 8.8%; 95% CI, 8.3-9.4, ADR 26.3%; 95% CI, 25.6-27.2). This finding also was observed for rates in the proximal colon. A logistic regression model (including withdrawal time) found that proximal ADR was statistically lower in the poor preparation category (odds ratio 0.45; 95% CI, 0.24-0.84; P < .01) than in adequately prepared colons.

Limitations: Homogeneous population.

Conclusion: In our sample, there was no significant difference in overall or proximal ADR or SDR between colonoscopies with fair versus optimal colon preparation quality. Poor colon preparation quality may reduce the proximal ADR.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenocarcinoma / diagnosis*
  • Adenoma / diagnosis*
  • Aged
  • Cathartics / therapeutic use
  • Cohort Studies
  • Colonic Polyps / diagnosis*
  • Colonoscopy / standards*
  • Colorectal Neoplasms / diagnosis*
  • Female
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • New Hampshire
  • Registries*


  • Cathartics