Endoscopic diagnosis and therapy is the examination of the esophagus, stomach and duodenum, as well the small intestine (via colonoscopy), the rectum (via rectoscopy). It also includes the endoscopic examination and treatment of the biliary tract and the pancreas (ERCP). Endosonography combines endoscopy with ultrasound and allows for a high-definition picture of variances in the upper and lower areas of the stomach and gastrointestinal tract.