The url for this article is: http://www.merck.com/pubs/mmanual_home/sec9/100.htm Diagnostic Tests for Digestive Disorders Tests performed on the digestive system make use of endoscopes (fiber-optic tubes that doctors use to view internal structures and to obtain tissue samples from inside the body), x-rays, ultrasound scans, radioactive tracers, and chemical measurements. These tests can help diagnose, locate, and sometimes treat a problem. Some tests require the digestive system to be cleared of stool (feces), some require 8 to 12 hours of fasting, and others don't require any preparation at all. The first steps in diagnosing a problem are always a medical history and a physical examination. However, symptoms of digestive disorders are often vague, so doctors may have difficulty determining precisely what's wrong. Also, psychologic disorders such as anxiety and depression can affect the digestive system and contribute to the symptoms. During a physical examination of a person with symptoms of a digestive problem, doctors examine the abdomen, anus, and rectum. They listen with a stethoscope for unusual sounds, feel for masses and enlarged organs, determine whether particular areas are sensitive to pressure, examine the anus and rectum by inserting a gloved finger, and obtain a small sample of stool to test for hidden (occult) blood. In women, a pelvic examination often helps distinguish digestive problems from gynecologic ones. A doctor recommends the appropriate tests, based on what the problem is and where it is. Esophageal Tests Barium studies, in which the patient swallows barium, are often performed on the esophagus. For such a study (called a barium swallow), doctors tend to use fluoroscopy, a continuous x-ray technique that allows barium to be observed or filmed as it passes through the esophagus. Fluoroscopy allows a doctor to see the contractions of the esophagus as well as any anatomic defects, such as obstructions or ulcers. Often, these images are recorded on film or videotape. Besides liquid barium, a patient may be given barium-coated food, so that a doctor can locate obstructions or view portions of the esophagus that aren't contracting normally. Both barium preparations taken together can show abnormalities such as esophageal webs (in which the esophagus is partially blocked by fibrous tissue), Zenker's diverticulum (an outpouching of the esophagus), esophageal erosions and ulcers, esophageal varices (esophageal varicose veins), and tumors. Manometry is a test in which a tube with pressure gauges along its surface is placed in the esophagus. Using this device (called a manometer), a doctor can determine whether contractions of the esophagus can propel food normally. An esophageal pH test (a test that measures acidity in the esophagus) can be performed during manometry. The test is used to determine if a person has acid reflux (reflux of stomach acid into the esophagus). (see page 491 in Chapter 101, Disorders of the Esophagus) One or more measurements may be taken. In the Bernstein test (esophageal acid perfusion test), a small amount of acid is placed in the esophagus through a nasogastric tube. This test, which is used to find out if chest pain is caused by acid irritation of the esophagus, is a good way to detect inflammation of the esophagus (esophagitis). Intubation Intubation is the process of passing a small, flexible plastic tube through the nose or mouth into the stomach or small intestine. This procedure may be used for diagnostic or treatment purposes. Although intubation may cause gagging and nausea in some patients, it isn't painful. The tube size varies according to the purpose. Nasogastric intubation (passage of a tube through the nose into the stomach) can be used to obtain a sample of stomach fluid. Doctors can then determine whether the stomach contains blood, or they can analyze the stomach's secretions for acidity, enzymes, and other characteristics. In poisoning victims, samples of the stomach fluid can be analyzed to identify the poison. In some cases, the tube is left in place, so that more samples can be obtained over several hours. Nasogastric intubation may also be used to treat certain conditions. For example, cool water can be infused into the stomach to help stop bleeding, poisons can be pumped out or neutralized with activated charcoal, or liquid food can be administered to people who can't swallow. Sometimes nasogastric intubation is used to continuously remove the contents of the stomach. The end of the tube is usually attached to a suction device, which removes gas and fluid from the stomach. This helps relieve pressure when the digestive system is blocked or otherwise not functioning properly. In nasoenteric intubation, a longer tube is passed through the nose, through the stomach, and into the small intestine. This procedure can be used to sample intestinal contents, continuously remove fluids, or provide food. A tube with a small device at the end can be used to perform a biopsy (obtain a sample of the small intestine for examination). The tissue may be analyzed for enzyme activity, examined under a microscope, or evaluated in other ways. Because the stomach and small intestine don't feel pain, the procedure is painless. Endoscopy Endoscopy is an examination of internal structures using a fiber-optic viewing tube (endoscope). When passed through the mouth, an endoscope can be used to examine the esophagus (esophagoscopy), the stomach (gastroscopy), and the small intestine (upper gastrointestinal endoscopy). When passed through the anus, an endoscope can be used to examine the rectum and the lower portion of the large intestine (sigmoidoscopy) and the entire large intestine (colonoscopy). Endoscopes range in diameter from about ï¿½ inch to about ï¿½ inch and range in length from about 1 foot to about 5 feet. Fiber-optic video systems allow the endoscope to be flexible while providing both a lighting source and a viewing system. Many endoscopes also are equipped with a small clipper to remove tissue samples and an electric probe to destroy abnormal tissue. Doctors can get a good view of the lining of the digestive system with an endoscope. They can see areas of irritation, ulcers, inflammation, and abnormal tissue growth. Usually, they can obtain samples for examination. Endoscopes can also be used for treatment. A doctor can pass different types of instruments through a small channel in the endoscope. Electrocautery can be used to close off a blood vessel and stop bleeding or to remove small growths, and a needle can be used to inject drugs into esophageal varices and stop their bleeding. Before having an endoscope passed through the mouth, a person usually must avoid food for several hours. Food in the stomach can obstruct the doctor's view and might be vomited up during the procedure. Before having an endoscope passed into the rectum and colon, a person usually takes laxatives and is given enemas to clear out any stool. Complications from endoscopy are relatively rare. Although endoscopes can injure or even perforate the digestive tract, they more commonly cause only irritation of the intestinal lining and a little bleeding. Laparoscopy Laparoscopy is an examination of the abdominal cavity using an endoscope. Laparoscopy is usually done with the patient under general anesthesia. After the appropriate area of the skin is washed with an antiseptic, a small incision is made, usually in the navel. Then an endoscope is passed into the abdominal cavity. A doctor can look for tumors or other abnormalities, examine virtually any organ in the abdominal cavity, obtain samples, and even do reparative surgery. X-ray Studies X-rays often are used to evaluate digestive problems. Plain abdominal x-rays, the standard x-rays of the abdomen, don't require any preparation on the patient's part. The x-rays generally are used to show an obstruction or paralysis of the digestive tract or abnormal air patterns in the abdominal cavity. These standard x-rays can also show enlargement of organs such as the liver, kidneys, and spleen. Barium studies often provide more information. After a person swallows barium, it looks white on x-rays and outlines the digestive tract, showing the contours and lining of the esophagus, stomach, and small intestine. The barium collects in abnormal areas, showing ulcers, tumors, erosions, and esophageal varices. X-rays may be taken at intervals to determine where the barium is. Or a fluoroscope may be used to observe the barium as it moves through the digestive tract. This process can also be filmed for later review. By observing the barium passing through the digestive tract, doctors can see how the esophagus and stomach function, determine if their contractions are normal, and tell whether food is getting blocked in the digestive system. Barium also can be given in an enema to outline the lower part of the large intestine. Then, x-rays can show polyps, tumors, or other structural abnormalities. This procedure may cause crampy pain, producing slight to moderate discomfort. Barium taken by mouth or given as an enema is eventually excreted in the stool, making the stool chalky white. Barium should be eliminated quickly after the studies because it can cause significant constipation. A gentle laxative can speed the elimination of barium. Paracentesis Paracentesis is the insertion of a needle into the abdominal cavity and the removal of fluid Normally, the abdominal cavity outside of the digestive tract contains only a small amount of fluid. However, fluid can accumulate in certain circumstances, such as when a person has a perforated stomach or intestine, liver disease, cancer, or a ruptured spleen. A doctor may use paracentesis to obtain a fluid sample for analysis or to remove excessive fluid. Before paracentesis, a physical examination, sometimes accompanied by an ultrasound scan, is performed to confirm that the abdominal cavity contains excessive fluid. Next, an area of the skin, generally just below the navel, is washed with an antiseptic solution and numbed with a small amount of anesthetic. A doctor then pushes a needle attached to a syringe through the skin and muscles of the abdominal wall and into the area of fluid accumulation. A small amount may be removed for laboratory testing, or up to several quarts may be removed to relieve distention. Abdominal Ultrasound Scan Ultrasound scanning uses sound waves to produce pictures of internal organs. It can show the size and shape of many organs, such as the liver and pancreas, and can also show abnormal areas within them. Ultrasound scanning can also show the presence of fluid. It isn't a good method, however, for examining the lining of the digestive tract, so it isn't used to look for tumors and causes of bleeding in the stomach, small intestine, or large intestine. An ultrasound scan is a painless procedure that poses no risk. The examiner (a doctor or technician) presses a small probe against the person's abdominal wall and directs sound waves to various parts of the abdomen by moving the probe. The pictures are then displayed on a video screen and recorded on video film. Occult Blood Tests Bleeding in the digestive system can be caused by something as insignificant as a little irritation or as serious as cancer. When bleeding is profuse, a person can vomit blood, pass bright red blood in the stool, or pass black, tarry stool (melena). Amounts of blood too small to be seen or to change the appearance of stool can be detected chemically, and the detection of such small amounts may provide early clues to the presence of ulcers, cancers, and other abnormalities. During a rectal examination, the doctor obtains a small amount of stool on a gloved finger. This sample is placed on a piece of filter paper impregnated with chemicals. After another chemical is added, the color of the sample will change if blood is present. Alternatively, the person can take home a kit containing the impregnated filter papers. The person places samples of stool from about three different bowel movements on the filter papers, which are then mailed in special containers back to the doctor for testing. If blood is detected, further examinations are needed to determine the source.