Gastrointestinal Disorders

The gastrointestinal (GI) system extends from the mouth to the anus and is comprised of the esophagus, stomach, duodenum, jejunum, ileum, colon, rectum, liver, pancreas, gall bladder, and biliary tract. Its primary functions are absorption of nutrients and elimination of wastes, although the liver and pancreas in particular fulfill many additional roles. Common symptoms of GI dysfunction include nausea, vomiting, changes in bowel movements, pain, and changes in weight.

GI disorders account for about 10 percent of the total burden of illness in the United States. According to the Centers for Disease Control and Prevention, in 2004, GI disorders accounted for 44.9 million office-based and 15.1 million emergency department visits. Obesity increases the chances of developing many different types of GI disorders, including gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), gall bladder disease, fatty liver disease, and GI cancers.

Because problems with many different organs within the GI system can present with similar symptoms, a careful history and examination is essential to identify the underlying cause. The timing of symptoms, for example, can help determine if diarrhea is related to food poisoning, irritable bowel syndrome, medication side effects, or other problems. Other important characteristics of symptoms, especially pain, include any associated factors that make the symptom better or worse, the quality of the pain, whether the pain radiates to other parts of the body, and the severity. On examination, the presence or absence of fever, abdominal tenderness or masses, changes in the overlying skin, pelvic examination, and color and consistency of the feces can all be helpful.

GI disorders can be further evaluated by laboratory studies. Special blood tests can evaluate the function of the pancreas or liver, check for proteins made by cancers, or for signs of infection or autoimmune disease. Stool tests for diarrhea can diagnose infections, bleeding, or malabsorption.

A range of radiology studies can also be helpful. Probably the most important test today is computed tomography (CT) scanning. This special technique reconstructs the appearance of the internal organs, so that many infections, cancers, and a range of other problems can be identified. CT is not perfect, though. Many people cannot receive the special intravenous contrast used for it because of an allergy or kidney problems. In other cases, the cause of the problem may not be seen at all on a CT scan because of its size, location, or underlying nature. In these instances, ultrasound, magnetic resonance imaging (MRI), special X-rays taken after swallowing barium, or directly visualizing the inside of the bowel with a special camera such as an endoscope may be helpful. Ultrasounds are especially good for looking at other structures in the abdomen such as the ovaries or bladder which can cause symptoms similar to that of GI problems. Barium X-rays allow radiologists to assess the contraction and movement of bowel which may cause swallowing problems, vomiting, constipation, or diarrhea.

Endoscopes are special cameras within long tubes that can be inserted through the mouth or anus which may obviate the need for surgery. Upper endoscopy evaluates the esophagus, stomach, and duodenum, while colonoscopy assesses the rectum, colon, and end of the small intestine. Endoscopy can be used to screen for cancers, take biopsies of the bowel or a mass, stop bleeding, or obtain additional ultrasound images of the liver and pancreas.

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