Gastrointestinal endoscopy has been attempted for over 200 years, but the introduction of semirigid gastroscopes in the middle of the twentieth century marked the dawn of the modern endoscopic era. Since then, rapid advances in endoscopic technology have led to dramatic changes in the diagnosis and treatment of many digestive diseases. Innovative endoscopic devices and new endoscopic treatment modalities continue to expand the use of endoscopy in patient care.
Flexible endoscopes provide either an optical image (transmitted over fiberoptic bundles) or an electronic video image (generated by a charge-coupled device in the tip of the endoscope). Operator controls permit deflection of the endoscope tip; fiberoptic bundles bring light to the tip of the endoscope; and working channels allow washing, suctioning, and the passage of instruments. Progressive changes in the diameter and stiffness of endoscopes have improved the ease and patient tolerance of endoscopy.
Upper endoscopy, also referred to as esophagogastroduodenoscopy (EGD), is performed by passing a flexible endoscope through the mouth into the esophagus, stomach, bulb, and second duodenum. The procedure is the best method of examining the upper gastrointestinal mucosa. While the upper gastrointestinal radiographic series has similar accuracy for diagnosis of duodenal ulcer (Fig. 291-1), EGD is superior for detection of gastric ulcers (Fig. 291-2) and flat mucosal lesions such as Barrett's esophagus (Fig. 291-3), and it permits directed biopsy and endoscopic therapy. Intravenous conscious sedation is given to most patients in the United States to ease the anxiety and discomfort of the procedure, although in many countries EGD is routinely performed with topical pharyngeal anesthesia only. Patient tolerance of unsedated EGD is improved by the use of an ultrathin, 5-mm diameter endoscope that can be passed transorally or transnasally.
Duodenal ulcers. A. Ulcer with a clean base. B. Ulcer with a visible vessel (arrow) in a patient with recent hemorrhage.
Gastric ulcers. A. Benign gastric ulcer. B. Malignant gastric ulcer involving greater curvature of stomach.
Barrett's esophagus. A. Pink tongues of Barrett's mucosa extending proximally from the gastroesophageal junction. B. Barrett's esophagus with a suspicious nodule (arrow) identified during endoscopic surveillance. C. Histologic finding of intramucosal adenocarcinoma in the endoscopically resected nodule. Tumor extends into the esophageal submucosa (arrow). D. Barrett's esophagus with locally advanced adenocarcinoma.
Colonoscopy is performed by passing a flexible colonoscope through the anal canal into the rectum and colon. The cecum is reached in >95% of cases, and the terminal ileum can often be examined. Colonoscopy is the gold standard for diagnosis of colonic mucosal disease. Colonoscopy has greater sensitivity than barium enema for colitis (Fig. 291-4), polyps (Fig. 291-5), and cancer (Fig. 291-6). CT colonography is an emerging technology that rivals colonoscopy's accuracy for detection of polyps and cancer. Conscious sedation is usually given before colonoscopy in the United States, although a willing patient and a skilled examiner can complete the procedure without sedation in many cases.
Causes of colitis. A. Chronic ulcerative colitis with diffuse ulcerations and exudates. B. Severe Crohn's colitis with deep ulcers. C. Pseudomembranous colitis with yellow, adherent pseudomembranes. D. Ischemic colitis with patchy mucosal edema, subepithelial hemorrhage, and cyanosis.
Colonic polyps. A. Pedunculated colon polyp on a thick stalk covered with normal mucosa (arrow). B. Sessile rectal polyp.
Colon adenocarcinoma growing into the lumen.
Flexible sigmoidoscopy is similar to colonoscopy but visualizes only the rectum and a variable portion of the left colon, typically to 60 cm from the anal verge. This procedure causes abdominal cramping, but it is brief and is usually performed without sedation. Flexible sigmoidoscopy is primarily used for evaluation of diarrhea and rectal outlet bleeding.
Three techniques are currently used to evaluate the small intestine, most often in patients presenting with presumed small-bowel bleeding. For capsule endoscopy the patient swallows a disposable capsule that contains a complementary metal oxide silicon (CMOS) chip camera. Color still images (Fig. 291-7) are transmitted wirelessly to an external receiver at several frames per second until the capsule's battery is exhausted or it is passed into the toilet. Although capsule endoscopy enables visualization of the jejunal and ileal mucosa beyond the reach of a conventional endoscope, it remains solely a diagnostic procedure at present.
Capsule endoscopy image of jejunal vascular ectasia.