Introduction: Colonoscopy remains the reference standard for diagnosing and monitoring colorectal cancer and for diagnosis and surveillance of inflammatory bowel disease. However, there is a limited knowledge of the patients' needs when undergoing colonoscopy and the challenges within in order to reduce the number of cancelled colonoscopies. The purpose of the study was to explore the experiences of undergoing bowel preparation and colonoscopy. Methods: The study was designed as a qualitative longitudinal interview study with an inductive research approach. Patients were considered for inclusion consecutively and selected based on the following criteria of variation: way of referral for colonoscopy (outpatient or screening), age and gender. The interviews were analyzed using qualitative content analysis, and results reported according to COREQ guidelines. Results: Based on the findings, three categories emerged: To weigh up participation, A greater challenge than expected, and Not so challenging after all. Throughout these categories, the experience of uncertainty was reported. Discussion: The process of undergoing bowel preparation and colonoscopy was influenced by uncertainty due to insufficient information. There is a need to strengthen the patientcentered care by adjusting the information to patient's needs to better support them in decision-making for participation, to better prepare them for the bowel preparation and to better prepare them for the procedure. In addition, it is vital that patients are provided with results of the colonoscopy that correspond to the timeframe specified in written information.

Background: Colonoscopy remains the reference standard for diagnosing and monitoring colorectal cancer and is also used for both diagnosis and surveillance of inflammatory bowel disease and it. Previous studies have shown that the preparation procedure was unpleasant for the patients, and they felt anxious about it alongside the anxiety related to the colonoscopy and the results. However, there is a limited knowledge of the patients’ needs when undergoing colonoscopy and the challenges within. The purpose of the study was to explore experiences of undergoing bowel preparation and colonoscopy.Methods: The study was designed as a qualitative longitudinal interview study with an inductive research approach. Twenty-five face to face interviews and twenty-one follow up interviews were conducted based on a semi structured interview guide. The interviews were analyzed using qualitative content analysis, and results reported according to COREQ guidelines.Results: Based on the findings, three categories emerged: To weigh up participation, A greater challenge than expected, and Not so challenging after all. Throughout these categories the experience of uncertainty was reported.Conclusions: The process of undergoing bowel preparation and colonoscopy was complex and influenced by uncertainty due to insufficient information. There is a need to strengthen the patient-centered care by adjusting the information to patient’s needs. It is necessary to tailor the written information to meet patients’ needs to better support them in decision-making for participation, to better prepare them for the bowel preparation and to better prepare them for the procedure. In addition, it is vital that patients are provided with results of the colonoscopy that correspond to the timeframe specified in written the information.