Digestive Diagnostic Procedures
How is a digestive disorder diagnosed?
In order to reach a diagnosis for digestive disorders, a thorough and accurate medical history will be taken by your physician, noting the symptoms you have experienced and any other pertinent information. A physical examination is also done to help assess the problem more completely.
Some patients need to undergo a more extensive diagnostic evaluation, which may include
laboratory tests,
imaging tests,
endoscopic procedures, and
other procedures. These tests may include any, or a combination of, the following.
Laboratory Tests
- Fecal occult blood test
A fecal occult blood test checks for hidden (occult) blood in the stool. It involves placing a very small amount of stool on a special card, which is then tested in the physician's office or sent to a laboratory.
- Stool culture
A stool culture checks for the presence of abnormal bacteria in the digestive tract that may cause diarrhea and other problems. A small sample of stool is collected and sent to a laboratory by your physician's office. In two or three days, the test will show whether abnormal bacteria are present.
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Imaging Tests
- Ultrasound
Ultrasound is a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. Gel is applied to the area of the body being studied, such as the abdomen, and a wand called a transducer is placed on the skin. The transducer sends sound waves into the body that bounce off organs and return to the ultrasound machine, producing an image on the monitor. A picture or video tape of the test is also made so it can be reviewed in the future.
- Computed tomography scan (CT or CAT scan)
This diagnostic imaging procedure uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
- Magnetic resonance imaging (MRI)
MRI is a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. The patient lies on a bed that moves into the cylindrical MRI machine. The machine takes a series of pictures of the inside of the body using a magnetic field and radio waves. The computer enhances the pictures produced. The test is painless, and does not involve exposure to radiation. Because the MRI machine is like a tunnel, some people are claustrophobic or unable to hold still during the test, and may be given a sedative to help them relax. Metal objects cannot be present in the MRI room, so persons with pacemakers or metal clips or rods inside the body cannot have this test done. All jewelry must be removed before the procedure.
- Oropharyngeal motility (also called modified barium swallow) study
This is a study in which the patient is given small amounts of a liquid containing barium to drink with a bottle, spoon, or cup. Barium is a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray. A series of x-rays are taken to evaluate what happens as the liquid is swallowed.
- Upper GI (gastrointestinal) series and small bowel follow through series.
Upper GI series is a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, duodenum (the first section of the small intestine) and small bowel. A fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is swallowed. X-rays are then taken to evaluate the digestive organs.
- Lower GI (gastrointestinal) series (also called barium enema)
A lower GI series is a procedure that examines the rectum, the large intestine, and the lower part of the small intestine. A fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is given into the rectum as an enema. An x-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems.
- Radioisotope gastric-emptying scan
During this test, the patient eats food containing a radioisotope, which is a slightly radioactive substance that will show up on a scan. The dosage of radiation from the radioisotope is very small and not harmful, but allows the radiologist to see the food in the stomach and how quickly it leaves the stomach, while the patient lies under a machine.
- Colorectal transit study
This test shows how well food moves through the colon. The patient swallows capsules containing small markers which are visible on x-ray. The patient follows a high-fiber diet during the course of the test, and the movement of the markers through the colon is monitored with abdominal x-rays taken several times three to seven days after the capsule is swallowed.
- Defecography
Defecography is an x-ray of the anorectal area that evaluates completeness of stool elimination, identifies anorectal abnormalities, and evaluates rectal muscle contractions and relaxation. During the examination, the patient's rectum is filled with a soft paste that is the same consistency as stool. The patient then sits on the toilet positioned inside an x-ray machine, and squeezes and relaxes the anus to expel the solution. The physician studies the x-rays to determine if anorectal problems occurred while the patient was emptying the paste from the rectum.
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Endoscopic Procedures
- Esophagogastroduodenoscopy (also called EGD or upper endoscopy)
An EGD (upper endoscopy) is a procedure that allows the physician to examine the inside of the esophagus, stomach, and duodenum. A thin, flexible, lighted tube, called an endoscope, is guided into the mouth and throat, then into the esophagus, stomach, and duodenum. The endoscope allows the physician to view the inside of this area of the body, as well as to insert instruments through a scope for the removal of a sample of tissue for biopsy (if necessary).
- Colonoscopy
Colonoscopy is a procedure that allows the physician to view the entire length of the large intestine (colon), and can often help identify abnormal growths, inflamed tissue, ulcers, and bleeding. It involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the physician to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered.
- Sigmoidoscopy
A sigmoidoscopy is a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine, and is helpful in identifying the causes of diarrhea, abdominal pain, constipation, abnormal growths, and bleeding. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum. The scope blows air into the intestine to inflate it and make viewing the inside easier.
- Endoscopic retrograde cholangiopancreatography (ERCP)
ERCP is a procedure that allows the physician to diagnose and treat problems in the liver, gallbladder, bile ducts, and pancreas. The procedure combines x-ray and the use of an endoscope - a long, flexible, lighted tube. The scope is guided through the patient's mouth and throat, then through the esophagus, stomach, and duodenum (the first part of the small intestine). The physician can examine the inside of these organs and detect any abnormalities. A tube is then passed through the scope, and a dye is injected which will allow the internal organs to appear on an x-ray.
- Capsule endoscopy
A capsule endoscopy helps doctors examine the small intestine. Because traditional procedures, such as an upper endoscopy or colonoscopy, cannot reach this part of the bowel, capsule endoscopy may be helpful in identifying causes of bleeding, detecting polyps, inflammatory bowel disease, ulcers, and tumors of the small intestine. A PillCam (a tiny camera contained in a capsule) is swallowed. The PillCam passes naturally through the digestive tract while transmitting video images to a data recorder. The data recorder is secured to a patient's waist by a belt for eight hours. Images of the small bowel are downloaded to a computer from the data recorder. The images are reviewed by a physician on a computer screen. Normally, the PillCam passes through the colon and is eliminated in the stool within 24 hours.
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Other Procedures
- Esophageal manometry
This test helps determine the function of the muscles in the esophagus. It is useful in evaluating swallowing abnormalities and other esophageal symptoms. It is frequently performed to assess adequacy of esophageal peristalsis before antireflux surgery is performed in gastroesophageal reflux disease. A small tube is guided into the nostril, then passed into the throat, and finally into the esophagus. The patient is asked to swallow sips of water to allow assessment of esophageal muscle function. The type of esophageal manometry performed (high resolution manometry) was designed and developed at our institution in the 1990s, and is the standard form of esophageal manometry in use today.
- 24-hour catheter based pH monitoring
An esophageal pH monitor measures the acidity inside of the esophagus. It is helpful in evaluating gastroesophageal reflux disease (GERD). A thin, plastic tube is placed into a nostril, guided down the throat, and then into the esophagus. The tube stops just above the lower esophageal sphincter, which is at the connection between the esophagus and the stomach. The distance to the lower esophageal sphincter is measured with an esophageal manometry study as described above. At the end of the tube inside the esophagus is a sensor that measures pH, or acidity. The other end of the tube outside the body is connected to a monitor that records the pH levels for a 24 to 48 hour period. Normal activity is encouraged during the study, and a diary is kept of symptoms experienced, or activity that might be suspicious for reflux, such as gagging or coughing, and any food intake by the patient. It is also recommended to keep a record of the time, type, and amount of food eaten. The patient punches buttons on the pH receiver to indicate symptoms. The pH readings are evaluated and compared to the patient's activity for that time period.
- 48-hour wireless pH monitoring
Instead of a catheter, a tiny pH probe is attached to the wall of the esophagus, that communicates with a receiver that patients wear on their belt. Similar to the 24 hour pH study, normal activity is encouraged, and a dairy is kept of symptoms. The patient is also asked to punch buttons on the receiver to note symptoms, so that symptom-reflux correlation can be assessed when the study is analyzed. This technique is more comfortable for the patient, but only provides acid recordings from one site in the esophagus. An endoscopy is typically required to measure the distance to the junction between the esophagus and the stomach.
- 24-hour catheter based pH-impedance monitoring
An esophageal pH-impedance monitor measures not just the acidity inside of the esophagus but can also determine all reflux events even if the reflux isn’t acidic. This test is similar to the 24 hour catheter based pH monitoring system. This test is particularly useful in determining if symptoms that persist on medication therapy for reflux disease are related to ongoing reflux events. Once again, normal activity is encouraged during the study, and a diary is kept of symptoms experienced, or activity that might be suspicious for reflux, such as gagging or coughing, and any food intake by the patient. It is also recommended to keep a record of the time, type, and amount of food eaten. The patient punches buttons on the receiver to record symptoms. The pH-impedance readings are evaluated and compared to the patient's activity for that time period.
- Anorectal manometry
This test helps determine the strength of the muscles in the rectum and anus. These muscles normally tighten to hold in a bowel movement and relax when a bowel movement is passed. Anorectal manometry is helpful in evaluating anorectal sphincter dysfunction and obstructed defecation, among other problems. A small tube is placed into the rectum to measure the pressures exerted by the sphincter muscles that ring the canal. High resolution anorectal manometry (similar to high resolution esophageal manometry) was developed in our institution, and is consistently used for testing here.
- ’Smart pill’
This test measures gastrointestinal transit, including gastric emptying time, small bowel transit time and colonic transit time. The device consists of a small pill sized device (smart pill) that a patient swallows. The pill measures pressures, acidity and temperature continuously, and transmits values to a device that patients wear on their belt. The combination of pressure and acidity can determine when the capsule moves out of the stomach into the small intestine, and from the small intestine to the large intestine. A drop in temperature is seen when the patient passes the capsule with a bowel movement. This test is relatively new, and is useful to measure delayed gastric emptying and delayed intestinal transit.
- Urea breath test for Helicobacter pylori
This test uses a radiolabeled meal to determine the presence of Helicobacter pylori. The bacteria break down urea in the meal to carbon dioxide containing the radiolabel, which is then measured in the breath. This is the most accurate nonendoscopic test for Helicobacter pylori.
- Secretin stimulation study
This test is useful to determine if there is uncontrolled production of a hormone named gastrin. Gastrin levels are checked in patients with recurrent ulcers and sometimes in patients with severe diarrhea where no other cause is found. If gastrin is found to be elevated, levels are rechecked after another hormone called secretin is given intravenously. The gastrin level increases significantly if there is uncontrolled production of the hormone, but decreases or remains the same in other instances.
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