A sigmoidoscope is a medical instrument, rigid or flexible, with a light at its tip, passed through the rectum to examine the sigmoid colon. The rigid version gives a quick office-based view of the rectum and lower sigmoid, useful for investigating bleeding, pain, or suspected inflammation. The flexible sigmoidoscope reaches further, around the bends of the sigmoid, and can take biopsies and remove small polyps. It examines less of the colon than a full colonoscopy but needs less preparation and no sedation, making it a practical screening tool. Findings of polyps or inflammation guide further investigation. Like all endoscopy, it trades a brief, undignified procedure for potentially life-saving early detection.