Early Bowel Resection for Terminal Ileal Crohn's Disease

The goal of this multicentre mixed -methods study is to understand the patient and clinician perspective on the ideal timing of an operation for Crohn's disease of the terminal ileum (last part of the small bowel). The main questions it aims to answer are: * What factors influence patients' and clinicians' preferences with regards to the timing of the first bowel resection for isolated Crohn's disease of the terminal ileum? * What are patients' and clinicians' views on 'early' bowel resection (as an alternative to medical therapy) in this context? * What are the facilitators and barriers to implementation of early surgery in practice? Participants will be patients with Crohn's disease of the terminal ileum and healthcare professionals involved in treating inflammatory bowel disease. Healthcare professionals have previously been asked to participate in an interview to understand their views on the role of surgery for Crohn's disease of the terminal ileum. They will now be invited to participate in a choice exercise to understand how much weight they attribute to various factors and outcomes when choosing between surgery and medication for Crohn's disease of the terminal ileum. Patients will be asked to participate in: 1. an interview about their treatment choices 2. a choice exercise to understand how much weight they attribute to various factors and outcomes when choosing between surgery and medication for Crohn's disease of the terminal ileum 3. a survey, for patients with a previous ileocaecal resection, assessing their experience of the operation