What Is a Double-Balloon Endoscope?- Equipment.- Indications, Contraindications, and Preoperative Examination.- Informed Consent.- Principle of Insertion and Characteristics.- Preparation and Premedication.- Preparation of Devices.- Specific Procedures for Insertion.- Expected Complications and Procedures to Address the Complications.- Endoscopic Diagnosis.- Diagnosis.- Small-Intestinal Tumor.- Stenosis of the Small Intestine.- Intestinal Ulcers and Erosions.- Postoperative Intestinal Lesions.- Vascular Disease.- Endoscopic Treatment.- Characteristics and Techniques of Endoscopic Treatment.- Hemostasis.- Polypectomy and Endoscopic Mucosal Resection.- Balloon Dilatation and Stenting.- Other Applications.- Double-Balloon Endoscopy as Colonoscopy.- Use in Patients with Previous Intestinal Surgery.- Removal of Foreign Bodies from the Small Intestine.