An endoscopy can detect a wide range of diseases, primarily related to the digestive system. Some of the key diseases and conditions that can be diagnosed by an endoscopy include:

• Cancer and tumors in the esophagus, stomach, colon, and other parts of the gastrointestinal (GI) tract.
• Esophageal varices, which are enlarged veins in the esophagus often linked to liver disease.
• Ulcers in the esophagus, stomach, or small intestine, often caused by Helicobacter pylori infection or NSAID use.
• Gastroesophageal reflux disease (GERD) and its complications such as Barrett’s esophagus.
• Celiac disease and other inflammatory bowel diseases like Crohn's disease and ulcerative colitis.
• Colorectal polyps and colorectal cancer.
• Bile duct problems and gallbladder diseases detected via specialized endoscopies like ERCP.
• Pancreatitis and related pancreatic abnormalities through endoscopic ultrasound.
• Helicobacter pylori infection in the stomach lining.
• Structural abnormalities causing swallowing disorders (dysphagia).
• Gastrointestinal bleeding sources including ulcers, polyps, varices, and diverticulosis.
• Liver diseases including cirrhosis, portal hypertension, and liver cancer, indirectly detected via signs like esophageal varices.

These diagnoses are made by visualizing the internal tissues and sometimes taking biopsies during the procedure, allowing early detection and appropriate treatment planning, including cancer screenings and interventions to control bleeding or remove polyps.