Automatic metrics from a new colon phantom can ensure basic competency in colonoscopy

Background: Colorectal cancer (CRC) is the third most diagnosed malignancy and the second leading cause of cancer-related death worldwide. As global screening programs expand, there is an increasing need for validated tools that ensure colonoscopy competence before trainees perform procedures on patients. This study examined validity evidence for a simulation-based colonoscopy test using a novel colon phantom with automated performance metrics. Methods: In this prospective observational study, 42 participants from Denmark, Norway, and Sweden were categorized as novice (0 procedures), intermediate (1–999), or experienced (>1000). Each completed three colonoscopy cases (EASY, STANDARD, ADVANCED 1) using the Mikoto simulator, which combines realistic haptics with automatic recording of key metrics: time to reach the caecum and the Sigmoid-Colon Elongation Index, a refined measure of unnecessary force and excessive stretching during scope advancement—reflecting the gentleness and finesse of scope manipulation. After successful intubation, participants performed a mucosal inspection scored by the PolypTumor Detection Score. Validity evidence was evaluated following Messick’s framework, and pass/fail standards were set using the contrasting groups’ method. Results: Inter-case reliability was excellent (Cronbach’s α = 0.93 for time; 0.83 for elongation index). Simulator metrics clearly discriminated between experience levels (p < 0.001), and strong inverse correlations were observed between time and elongation index (r = − 0.78 to − 0.89), indicating that the fastest participants were also the gentlest. None of the novices passed, while 36% of intermediates and 67% of experts met all non-compensatory pass criteria. Conclusion: The Mikoto colon phantom offers objective, reliable, and automated assessment of colonoscopy competence, integrating both efficiency and tissue-friendly technique. Strong validity evidence supports its use for proficiency-based training and skills maintenance, as failure among many experienced endoscopists highlights its potential for periodic re-evaluation and continued professional development.