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.
Several GI disorders are more common with obesity. In GERD, stomach acid flows from the stomach back up into the esophagus, causing irritation of the esophagus’s delicate lining. It is often associated with pain or pressure in the chest. It can lead to scarring and narrowing of the esophagus and increases the risk of developing one type of esophageal cancer. People with higher body mass indexes have more self-reported heartburn and regurgitation symptoms than their thinner counterparts.
IBS is a functional disorder—that is, scientists have been unable to identify a specific cause for it—characterized by chronic abdominal pain with diarrhea, constipation, or both. Obesity is associated with symptoms of bloating, upper abdominal pain, and diarrhea. People with IBS tend to have changes in GI motility, increased sensitivity to bloating and distension, coexisting psychological problems, and higher stress levels.
Gall bladder disease is the most common gastrointestinal disorder in obese individuals. Both obesity and rapid weight loss are associated with the development of gallstones. Gallstones form when liquid bile stored in the gallbladder hardens into pieces of stone-like material. Obesity increases the cholesterol content of bile and decreases the contraction of the gall bladder, predisposing to cholesterol-rich gallstones. These usually remain silent, but can cause right upper abdominal pain within 30 minutes of eating a fatty meal, pain between the shoulder blades or below the right shoulder, and nausea or vomiting. Stones that have become stuck in the neck of gall bladder commonly precipitate cholecystitis, or infection of the gall bladder. It produces symptoms such as right upper abdominal pain, fever, nausea, and vomiting.
Acute pancreatitis, or inflammation of the pancreas, is usually caused by gallstones or drinking alcohol. It can cause severe pain, nausea, and vomiting. Symptoms are typically worsened by eating, because this stimulates the pancreas to try to release more enzymes to digest food entering the duodenum. The inflammation can lead to pooling of fluid around the pancreas and bowel, which in severe cases can lead to shock and even death. People who are obese are more likely to develop severe pancreatitis and its complications.
Cancers of the GI tract are closely associated with obesity, and may all present with unintentional weight loss. Adenocarcinoma of the esophagus, often related to long-standing GERD, may present with swallowing problems. Stomach cancer can present with pain or dark tarry stools, while colon cancer may be heralded by a change in the frequency or caliber of bowel movements, blood in the stool, or dark tarry stools. Pancreatic cancer may have no symptoms until it blocks the drainage of bile into the intestine, causing yellowing of the skin and eyes, or may present with abdominal pain.
Abdominal hernias occur when part of the bowel or fatty tissue protrudes through a weakened area of the abdominal wall such as around the umbilicus or at the site of a past surgery. The significance of abdominal hernias varies widely. Many cause no symptoms at all.
Hemorrhoids are engorged blood vessels in or around the anus, often caused by straining from constipation or increased pressure in the pelvis, as with pregnancy. Hemorrhoids may be associated with pain, bleeding, itching, or the sensation of a lump. Avoiding constipation by drinking fluids and eating lots of fiber can help prevent and treat hemorrhoids.
Colon Cancer; Fatty Liver; Gall Bladder Disease; Gastroesophageal Reflux (GERD)
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