This prospective observational study investigates how participants experience screening colonoscopy within the Danish colorectal cancer screening program and how these experiences relate to clinical findings, procedural factors, and future participation in screening.

The study aims to evaluate patient-reported experiences such as pain, discomfort, preparation burden, emotional responses, and perceptions of healthcare staff, as well as staff-assessed pain during the procedure. These experiences will be examined in relation to colonoscopy findings, including polyp detection, histology, risk stratification, and colorectal cancer detection. In addition, procedure-specific variables such as insertion time, bowel preparation quality, completeness of colonoscopy, medication use, and adenoma detection rate will be analyzed in relation to patient experience.

A key focus is whether the experience of screening colonoscopy influences subsequent participation in the colorectal cancer screening program, particularly among individuals classified as low risk and re-invited for screening after two years. Registry-based follow-up will be used to assess re-participation.

Data are collected prospectively from two sources: (1) real-time procedure data entered by healthcare staff during colonoscopy and (2) patient-reported outcomes collected via a questionnaire completed shortly after the procedure. Additional outcome data are obtained from electronic medical records and national health and screening registries.

The study has no single predefined hypothesis. Instead, it serves as a data-generating platform designed to address both predefined and future research questions related to screening colonoscopy experiences, quality indicators, and screening adherence.

Inclusion Criteria:

• Adults undergoing screening-derived colonoscopy as part of the Danish colorectal cancer screening program
• Written informed consent

Exclusion Criteria:

• Inability to understand or communicate in Danish
• Lack of decision-making capacity, including cognitive impairment due to dementia or brain injury
• Declines or withdraws informed consent

Adults undergoing a screening colonoscpy