04/28/2026
Withdrawal time in colonoscopy: one size does not fit all
Colonoscopy, the colorectal imaging test commonly used for primary colorectal cancer (CRC) screening, has been shown to reduce CRC incidence and prevent CRC mortality; however, its effectiveness depends highly on operator's technique, as well as on the quality of bowel preparation. Regarding operator's performance, quality is assessed through detection indicators such as adenoma detection rate (ADR), advanced ADR (AADR), number of conventional adenomas detected per colonoscopy in patients (APC), sessile serrated lesion detection rate (SSLDR), polyp detection rate (PDR), polyps per colonoscopy (PPC), and average withdrawal time (WT) in normal colonoscopies.1 ADR, defined as the percentage of patients aged ≥45 years undergoing colonoscopy for screening, surveillance, or diagnostic indications in whom at least 1 conventional adenoma is detected and pathologically confirmed, is considered the benchmark quality indicator. Currently, a minimum threshold of 35% for the ADR is recommended.1 Postcolonoscopy CRC (PCCRC) incidence and mortality decrease by approximately 3% and 5%, respectively, for every 1% increase in the ADR, and the risk continues to fall as ADR increases above 35%.2 Average WT includes the time needed to inspect the entire colon from the cecum to retroflexion in the re**um in normal colonoscopies with no polypectomy, biopsy sampling, or therapy. Although WT cannot replace ADR as the primary quality marker, longer WT has been correlated to higher ADR and consequently to lower PCCRC rates.3,4 Several studies have demonstrated that optimal adenoma detection typically requires at least 8 to 9 minutes to prevent PCCRC,4-6 leading to endorsement of 8 to 9 minutes as acceptable WT by current guidelines.
In this issue of Gastrointestinal Endoscopy, Taghiakbari et al,7 introduce for the first time corrected WT (cWT) as a quality marker in colonoscopy, cWT being the WT adjusted by subtracting intervention times. The authors further explore the time required for effective adenoma detection by prospectively evaluating cWT and WT in full-length video recordings of 1072 colonoscopy procedures. Using detailed statistical analysis, the authors determined the time required to achieve adequate ADR thresholds (≥26% and >35%) across different endoscopists’ performance levels and also assessed the impact of incremental increases in cWT and uncorrected WT on all key metrics (ADR, AADR, SSLDR, APC, PDR, and PPC). Similar adjusted WT measurements have been reported in prior studies.5 CWT offers a more precise measurement of actual inspection time, making it a truer reflection of endoscopist technique and inspection quality. To implicate, however, real-time calculation of cWT in everyday clinical practice presents several practical challenges. Unlike conventional WT, which can be measured automatically by most endoscopy processors, cWT requires real-time annotation and subtraction of the duration of specific therapeutic or cleaning interventions. In a busy endoscopy suite, this demands either additional personnel dedicated to timing and documentation, or the manual recording by the endoscopist or assisting nurse, tasks that can disrupt workflow. It is true that in the future, with artificial intelligence (AI) systems evolution, AI could interact with endoscopists and supply precise cWT calculations. However, in the present, consistent and accurate timing may vary widely across personnel and institutions, potentially undermining the reliability and reproducibility of cWT data. In this study, the authors have calculated that the mean of per-polyp intervention time was 1 minute 36 seconds across all procedures. Given that prolonged WT is a readily implementable measure requiring no additional technology or resources, this study provides evidence that cWT is a mean to improve ADR and induces the idea of appropriately calculating cWT by subtracting 1 minute 36 seconds per polyp to WT or for endoscopists who cannot routinely calculate cWT, to judge whether adequate WT is reached by adding 1 minute 36 seconds per removed polyp beyond the guideline-recommended 8 to 9 minutes.
As expected, cWT and WT prolongation improved ADR across all endoscopists irrespective of their experience level, with an average absolute ADR increase of 1.6% per additional minute of cWT. Current guidelines do not specify an appropriate WT when accounting for intervention time, and therapeutic interventions during withdrawal may mask true differences in inspection technique between high- and low-performing endoscopists. For this reason, the authors also analyzed cWT and WT separately by performance level (ADR
