Matched analysis of colonic polyp characteristics between colon capsule endoscopy, lower GI endoscopy and histopathology

Introduction

Following the introduction of colon capsule endoscopy (CCE) in the NHS England pilot study across England, colon capsules have been increasingly recognised as an alternative diagnostic modality for lower GI investigations. The referral criteria for lower GI optical endoscopy (flexible sigmoidoscopy or colonoscopy) are based on the identified polyps’ size, number and locations. Therefore, the accuracy of polyp detection and characterisation by CCE is critical to avoid unnecessary procedures.

Aim

To compare the size, number, and location of polyps identified on CCE compared with lower GI optical endoscopy (OE) and histopathology (HP).

Methods

In this retrospective audit, we screened through 96 CCEs performed between May 2021 and Jan 2023 in a tertiary centre with 2 regular readers in the UK. We identified paired polyps on CCE, subsequent OE and HP. The polyps detected in CCE videos were matched with the corresponding OE images based on morphology, other surrounding distinctive features such as mucosal folds or vessels pattern and the location. Polyps detected in CCE were marked and measured using the Rapid software (Medtronic, USA) standard measuring tool. The size was then compared against the subsequent OE and HP findings using paired t-tests.

Results

Following CCE, 47% of patients proceed to have either colonoscopy (30%) or flexible sigmoidoscopy(17%). The total number of polyps identified on CCE and OE were 75 and 51, respectively. Only 30 paired polyps were identified. When compared to OE and HP, CCE overestimated the polyp size by 2.6mm (95% CI 1.2–4mm) and 3.5mm (95%CI 2.4–4.6mm), respectively. The overall size overestimation was statistically significant in both comparisons, i.e. CCE vs OE (p=0.0005) and CCE vs HP (p=0.000004). The comparison of size estimation was further evaluated in 3 polyp size categories: i) <6mm; ii) 6>size<10mm; and, iii) size≥10mm. (see table 1) Overall, 22% of unnecessary lower GI endoscopies were performed due to overestimated polyp size on CCE (17% was polyps>10mm and 5% between 6 and 10mm).

Conclusions

Our data confirm the previously reported polyp overestimation in CCE in the literature.¹ To improve the scalability and cost-effectiveness of CCE, a more accurate CCE polyp size-measuring tool might be indicated.

Reference

Blanes-Vidal V, Nadimi ES, Buijs MM, Baatrup G. Capsule endoscopy vs. colonoscopy vs. histopathology in colorectal cancer screening: matched analyses of polyp size, morphology, and location estimates. Int J Colorectal Dis. 2018 Sep 1;33(9):1309–12.