Date of Award

January 2024

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)



First Advisor

Jill K. Gaidos


Compared to the general population, patients with inflammatory bowel disease (IBD) are more at risk for developing colorectal dysplasia and neoplasia in their lifetime. Given this increased risk, current guidelines recommend that patients with IBD involving at least one-third of the colon undergo routine surveillance colonoscopy exams every one to five years to monitor disease activity and severity. Colonoscopy withdrawal time (CWT) is considered an important predictor of adenoma detection and a quality metric of colonoscopy within the general population. Society organizations including the American Society for Gastrointestinal Endoscopy and the American College of Gastroenterology have proposed a minimum average CWT of six minutes for optimal detection of dysplastic and neoplastic lesions, though recent studies have proposed to aim for a CWT of eight to nine minutes. While several CWT cutoffs have been proposed within the general population, the ideal CWT in patients with IBD has not been determined. We aimed to identify the optimal CWT associated with the detection of polypoid dysplasia in patients with IBD. This is a single-center, retrospective study from 6/1/2017-9/1/2022 of adult subjects with IBD in endoscopic remission undergoing surveillance via high-definition white light colonoscopy. We included subjects ≥18 years of age with a confirmed diagnosis of IBD involving the colon for at least eight years, or a confirmed diagnosis of IBD and comorbid primary sclerosing cholangitis. We excluded subjects with incomplete colonoscopy, subjects with prior ileocolonic or colonic resections, and colonoscopy exams with chromoendoscopy. The primary outcome was the association between CWT and polypoid dysplasia detection. We also sought to identify an optimal CWT cutoff associated with polypoid dysplasia detection. Continuous variables were analyzed using an unpaired student’s t-test and categorical variables were analyzed using a chi-square test. Multivariate analyses were performed to assess factors associated with polypoid dysplasia. A total of 259 subjects (mean age 56 ± 14.8 years; 51.3% female, 68% with UC; 8.9% with primary sclerosing cholangitis) underwent 330 colonoscopies. The median CWT in the study cohort was 22 minutes [interquartile range (IQR) 15-29].

Polypoid dysplasia was detected in 17.3% (n=57) of procedures. Compared to subjects without polypoid dysplasia, subjects with polypoid dysplasia were more likely to be older (p<0.001) and have a personal history of polypoid dysplasia (p<0.001) and invisible dysplasia (p=0.023). The mean CWT was significantly longer in the polypoid dysplasia group at 26 minutes (IQR 20-38.5) vs. 21 minutes (IQR 15-28) in procedures without polypoid dysplasia (p<0.001). On multivariable analysis, increased age (p < 0.001), increased CWT (p=0.001), and personal history of polypoid dysplasia (p=0.013) were independently associated with the detection of polypoid dysplasia.A CWT of ≥ 15 minutes [odds ratio (OR) 2.71, 95% CI: 1.11-6.6; p=0.02] and not ≥ 9 minutes (OR 2.57, 95% CI: 0.33-20.2; p=0.35) is significantly associated with detection of polypoid dysplasia. CWT did independently correlate with polypoid dysplasia detection for patients with IBD undergoing surveillance via high-definition white light colonoscopy. Specifically, a mean CWT of ≥ 15 minutes was independently associated with the detection of polypoid dysplasia, while a mean CWT of ≥ 9 minutes was not. Moving forward, future prospective studies are needed to corroborate the findings of this study.


This is an Open Access Thesis.

Open Access

This Article is Open Access