Original Contribution

Colon/Small Bowel

Variation in Pathologist Classification of Colorectal Adenomas and Serrated Polyps

  • The American Journal of Gastroenterology volume 113, pages 431439 (2018)
  • doi:10.1038/ajg.2017.496
  • Download Citation



Endoscopist quality measures such as adenoma detection rate (ADR) and serrated polyp detection rates (SPDRs) depend on pathologist classification of histology. Although variation in pathologic interpretation is recognized, we add to the literature by quantifying the impact of pathologic variability on endoscopist performance.


We used natural language processing to abstract relevant data from colonoscopy and related pathology reports performed over 2 years at four clinical sites. We quantified each pathologist’s likelihood of classifying polyp specimens as adenomas or serrated polyps. We estimated the impact on endoscopists’ ADR and SPDR of sending their specimens to pathologists with higher or lower classification rates.


We observed 85,526 colonoscopies performed by 119 endoscopists; 50,453 had a polyp specimen, which were analyzed by 48 pathologists. There was greater variation across pathologists in classification of serrated polyps than in classification of adenomas. We estimate the endoscopist’s average SPDR would be 0.5% if all their specimens were analyzed by the pathologist in our sample with the lowest classification rate and 12.0% if all their specimens were analyzed by the pathologist with the highest classification rate. In contrast, the endoscopist’s average ADR would be 28.5% and 42.4% if their specimens were analyzed by the pathologist with lowest and highest classification rate, respectively.


There is significant variation in pathologic interpretation, which more substantially affects endoscopist SPDR than ADR.

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Author information


  1. Harvard Medical School, Boston Massachusetts, USA

    • Rebecca A Gourevitch
    • , Sherri Rose
    •  & Ateev Mehrotra
  2. Division of Gastroenterology and Hepatology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA

    • Seth D Crockett
  3. Department of Biomedical Informatics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

    • Michele Morris
  4. Kaiser Permanente of Washington Health Research Institute (formerly Group Health Research Institute), Seattle, Washington, USA

    • David S Carrell
  5. Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA

    • Julia B Greer
    •  & Robert E Schoen
  6. Department of Pathology, UPMC Presbyterian Hospital, Pittsburgh, Pennsylvania, USA

    • Reetesh K Pai
  7. Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

    • Ateev Mehrotra


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Competing interests

Guarantor of the article: Ateev Mehrotra, MD, MPH.

Specific author contributions: Rebecca A. Gourevitch: study concept and design, analysis and interpretation of data, statistical analysis, drafting of the manuscript. Sherri Rose: study concept and design, analysis and interpretation of data, critical revision of the manuscript for important intellectual content, statistical analysis. Seth D. Crockett: study concept and design, acquisition of data, critical revision of the manuscript for important intellectual content. Michele Morris: acquisition of data, analysis and interpretation of the data. David S. Carrell: study concept and design, acquisition of data, critical revision of the manuscript for important intellectual content. Julia B. Greer: study concept and design, critical revision of the manuscript for important intellectual content. Reetesh K. Pai: critical revision of the manuscript for important intellectual content. Robert E. Schoen: study concept and design, acquisition of data, critical revision of the manuscript for important intellectual content. Ateev Mehrotra: study concept and design, acquisition of data, drafting of manuscript, critical revision of the manuscript for important intellectual content, obtained funding.

Financial support: This paper was supported by a grant from the National Cancer Institute (5R01CA168959) and Rebecca A. Gourevitch’s time was partially supported by T32HS000055 from the Agency for Healthcare Research and Quality.

Potential competing interest: None.

Corresponding author

Correspondence to Ateev Mehrotra.

Supplementary information

SUPPLEMENTARY MATERIAL is linked to the online version of the paper at http://www.nature.com/ajg