Digestive Diagnostic Procedures for Children

To diagnose digestive and liver problems, your child's doctor will do a thorough medical history and physical exam to help assess the problem more completely.

Some children may need to undergo a more extensive diagnostic evaluation, which may include lab tests, imaging tests, or endoscopic procedures. These tests may include any, or all, of the following:

Lab tests

• Albumin level. Albumin is a protein made by the liver. It is found in the bloodstream and is associated with may chronic liver disorders. For this test,  a sample of blood is taken from your child's vein.

• Bilirubin level. Bilirubin is produced by the liver and is excreted in the bile. Elevated levels of bilirubin may indicate an obstruction of bile flow or a defect in the processing of bile by the liver. For this test, a sample of blood is taken from your child's vein.

• Complete blood count (CBC). A sample of blood is taken from your child's finger or vein, and the different types of cells in the bloodstream are examined. White blood cells multiply when infection is present. Red blood cells will be present in smaller amounts than normal if blood has been lost, if the diet has been inadequate, or with certain diseases.

• Electrolyte tests. A sample of blood is taken from your child's vein, and the amounts of minerals known as electrolytes are measured. This includes sodium, potassium, calcium, and glucose. These minerals are important for the body to function properly. Children who have lost large amounts of fluid due to vomiting or diarrhea often lose large amounts of the various electrolytes as well. Your child's doctor uses electrolyte tests to help determine when your child might need extra fluids given intravenously or other medications to help with dehydration and mineral loss.

• Fecal fat test. With this test, you child is asked to eat a high-fat diet for several days. You collect small samples of stool in sealed containers for 3 days. Your child's doctor will send them to a lab. The amount of fat contained in your child's stool is measured. If the digestive tract is working properly, only small amounts of fat will be present in the stool. The rest of the fat that was in the diet will have been digested and reabsorbed by the body. If your child has a condition known as malabsorption, then the intestinal tract cannot digest fats as well as it should, and elevated amounts of fat will pass through into the stool.

• 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 doctor's office or sent to a lab.

• Hydrogen breath test. This test measures the amount of hydrogen in the breath, and helps diagnose several digestive problems. These include carbohydrate intolerance, bacterial overgrowth of the small intestine, and rapid transit of food through the small intestine. Normally, digestive enzymes in the stomach and upper small intestine digest carbohydrates in the food we eat.

  Bacteria in the lower small intestine digest the rest of the carbohydrates, and produce hydrogen gas in the process. If carbohydrates are largely undigested by the time they reach the small intestine, bacteria will complete the digestive process; however, hydrogen gas being produced will cause cramps and bloating. This can happen if the carbohydrates are not digested properly, if food moves through the digestive system quickly, or if there are large numbers of bacteria present. The amount of hydrogen in the breath is greater than usual when bacteria in the intestines digest carbohydrates instead of digestion being done by the normal digestive enzymes.

  The child is told to fast overnight, and then breath samples are obtained by having the child blow into a balloon periodically. He or she will be given samples of a carbohydrate (such as lactose or sorbitol) to drink. The amount of hydrogen produced in the breath will be measured at the start of the test, and at intervals after carbohydrates are given.

• Lactose tolerance test. This test helps determine if a child has trouble digesting lactose properly. Your child is given a liquid containing lactose to drink. Several blood samples are taken over a two-hour period to measure the amount of glucose (sugar) present in the bloodstream. If lactose is digested normally, blood glucose rises. If lactose is not digested as it should be, then the blood glucose level does not change throughout the test.

• Liver enzymes. A sample of blood is taken from your child's vein, and the amounts of enzymes that the liver normally makes are measured. Elevated levels of liver enzymes can alert doctors to liver damage or injury, since the enzymes leak from the liver into the bloodstream under these circumstances.

• Prothrombin time (PT) test. This test measures the time it takes for blood to clot. Blood clotting requires vitamin K and a protein made by the liver. Liver cell damage and bile flow obstruction can both interfere with the regulation of blood clotting.

• 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 lab by your doctor's office. In 2 to 3 days, the test will show whether abnormal bacteria are present.

• Urea breath test. This test helps diagnose the presence of Helicobacter pylori (H. pylori) in the digestive tract. Your child swallows a capsule containing urea. If H. pylori is present in the stomach, then the urea will be converted into nitrogen and carbon. The carbon changes to carbon dioxide and moves into the bloodstream, and then into the lungs where it is exhaled. Your child breathes into a balloon, and the amount of carbon in the breath is measured. A positive test, meaning carbon is present, indicates the presence of H. pylori. A negative test, meaning no carbon is detected, indicates no H. pylori is present.

Imaging tests

• Computed tomography scan (CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) 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. Your child will lie on a bed that moves into a doughnut shaped machine that takes many pictures of different areas of the body. Because the machine is noisy, and because your child may need to lie still for awhile with his or her arms over the head, a sedative might be given to help your child remain still during the procedure.

• Lower GI (gastrointestinal) series (also called barium enema). 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.

• Magnetic resonance imaging (MRI). 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. Your child lies on a bed that moves into the cylindrical MRI scanner. 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 scanner is like a tunnel, some children are claustrophobic or unable to hold still during the test, and may be given medication to help them relax or sleep. Metal objects cannot be present in the MRI room, so children 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 (swallowing) study. Your child is given small amounts of a liquid containing barium to drink with a bottle, spoon, or cup. Barium shows up well on X-ray. A series of X-rays are taken to evaluate what happens as your child swallows the liquid. This procedure is also called a modified barium swallow.

• Ultrasound. An imaging technique that 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.

• Upper GI (gastrointestinal) series. A test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section 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 swallowed. X-rays are then taken to evaluate the digestive organs.

Endoscopic procedures

• Colonoscopy. Colonoscopy is a procedure that allows the doctor to view the entire length of the large intestine (colon). It can 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 doctor to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered.

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• Endoscopic retrograde cholangiopancreatography (ERCP). ERCP is a procedure that allows the doctor to diagnose and treat problems in the liver, gallbladder, bile ducts, and pancreas. The procedure combines X-ray and the use of an endoscope, which is a long, flexible, lighted tube. The scope is guided through the mouth and throat, then through the esophagus, stomach, and duodenum (the first part of the small intestine). The doctor 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 X-ray.

• Esophagogastroduodenoscopy (EGD) (also called upper endoscopy). EGD (upper endoscopy) is a procedure that allows the doctor to look at 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 doctor 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).

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Other procedures

• 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 malformations and Hirschsprung's disease, among other problems. A small tube is placed into the rectum, and the pressures inside the anus and rectum are measured.

• Esophageal manometry. This test helps determine the strength of the muscles in the esophagus. It is useful in evaluating gastroesophageal reflux and swallowing abnormalities. A small tube is guided into the nostril, then passed into the throat and finally into the esophagus. The pressure the esophageal muscles produce at rest is then measured.

• Esophageal 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. 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. It is also recommended to keep a record of the time, type, and amount of food eaten. The pH readings are evaluated and compared to the child's activity for that time period.

• Magnetic resonance cholangiopancreatography (MRCP). This uses magnetic resonance imaging (MRI) to take pictures of the bile ducts. The machine uses radio waves and magnets to scan internal organs and tissues.

• 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. This procedure is helpful in identifying causes of bleeding, detecting polyps, inflammatory bowel disease, ulcers, and tumors of the small intestine. A sensor device is placed on a patient's abdomen and a pillcam (capsule endoscope) 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 on a computer from the data recorder. The images are reviewed by a doctor on a computer screen. Normally, the pillcam passes through the colon and is eliminated in the stool within 24 hours.

• Liver biopsy. A liver biopsy helps diagnose liver diseases. A small sample of liver tissue is taken with a special biopsy needle and examined for abnormalities. Children are sometimes given medication to minimize their anxiety during the procedure. A small area of skin over the liver is numbed with a local anesthetic. The anesthetic is then injected deeper under the skin to numb the area that the biopsy needle will pass through and reduce the discomfort of the test. The biopsy needle is quickly inserted through the skin and into the liver, and then withdrawn. Sometimes, an ultrasound of the liver is done at the same time to help the doctor know exactly where to take the tissue samples. After a liver biopsy, a health care professional will observe the child for bleeding problems for a few hours. Pain medications will be given, if needed.