Special Imaging Studies
Your doctor may have recently requested that you have an examination of your digestive tract at your hospital outpatient radiology (x-ray) department. If you are scheduled to have such an exam, it is important that you understand why the test is necessary and what steps are needed for proper preparation. This pamphlet reviews the most common studies performed. If you have any additional questions, please ask.
Why Do I Need This Test?
Tests such as these are done to provide your doctor with additional information about the status of your digestive system. This helps your doctor decide what, if any, problems may be present, and the best remedy in your particular case. Often, x-rays are requested to evaluate an organ that cannot be seen by other means. For instance, a diseased gallbladder may not show up in blood tests, nor can a standard "scope" test see this organ. But, specialized x-rays and other studies can visualize the gallbladder and determine if stones or disease are present. Sometimes x-rays are used to visualize part of the intestine that cannot be reached with a scope exam. A common example would be a barium x-ray of the portion of the small intestine that lies beyond the reach of a upper or lower scope test. Occasionally, a barium x-ray of the colon is ordered when severe diverticulosis or other problems prevent completion of a full colonoscopy "scope" examination. If you need to have x-rays or other special studies performed, your doctor will explain what tests are necessary and why. Here is a summary of the four basic exams:
Where Is The Test Performed?
You may not realize that when ordinary x-rays are taken, only your bones show up. X-ray beams pass right through the soft tissues of your body, such as the intestines, liver, kidneys, etc., making them almost invisible. Barium is an inert, harmless mineral that prevents the passage of x-rays - just as your hand blocks sunlight. During an Upper Gastrointestinal Series, or Upper GI Series, you are given a flavored "milkshake" of liquid barium to drink. The barium fills your stomach making it visible on the x-ray film. The standard Upper GI evaluates the esophagus, stomach, and first portion of your small intestine - called the duodenum. This takes about 30 minutes. If your doctor requests that the remaining twenty feet of small intestine also be evaluated, the test is termed a Small Bowel Series and takes an additional two to three hours to complete. Both examinations require fasting after midnight, but no laxative preparation is necessary, nor is a driver needed.
A similar examination of the large intestine, or colon, is called a Lower Gastrointestinal Series, or Lower GI. Of course, in this instance, the barium is not swallowed, but is given rectally as an enema - thus the more common name, Barium Enema. This examination takes less than an hour and requires fasting as well as an unpleasant laxative and dietary preparation the day or two before. Prep instructions vary and will be provided by our staff. Be sure to follow them exactly so the test need not be repeated.
Another test often performed in the x-ray department does not use x-rays at all - an Abdominal Ultrasound. Also known as a Sonogram, this test utilizes specialized sound waves that bounce off your internal organs to obtain images - much like the way a submarine uses sonar to locate the enemy. The pitch, or frequency, of these sound waves is far above the range of human hearing, hence the name Ultrasound. An Ultrasound is also the examination that is given to pregnant women to check the size of their baby before delivery. This same exam can also be used to visualize certain digestive organs, such as the gallbladder, liver and pancreas as well as the main abdominal blood vessel, the aorta.
During an ultrasound, you will be positioned on an examination table and a gel will be applied to your abdomen. A small probe, called a transducer, will be passed over the surface of your abdomen. The test is quick, painless, and requires very little preparation. Fasting after midnight is usually required. A driver is not necessary. If your doctor also requests an evaluation of the lower abdomen, or pelvis, a full urinary bladder is also required.
A CAT Scan, also known as CT Scan, uses a complex computerized x-ray scanner that takes multiple views of your abdominal organs as you lie on a flat table. A high speed computer analyses the information to create cross sectional images of parts of your body. The radiologist (x-ray doctor) can then view these images in sequence, like slices in a loaf of bread, and create a virtual three dimensional view of your abdominal organs. CT is best suited for viewing the more solid digestive organs like liver, pancreas and kidney, and less suited for viewing the hollow air field intestinal tract.
Preparation is simple, however there are a few concerns. First, since dehydration can increase the risk of side effects, it is important that you drink plenty of fluids up until four hours before the examination. During the last four hours, you should avoid all food and drink.
Since the contrast material can worsen previously existing kidney disease, the radiologist usually requests proof of normal kidney function. This requires a blood test.
To make the examination more accurate, you will be asked to drink an oral contrast solution before the scan. Additional contrast material may also be given by vein to enhance the images. Since this solution contains iodine, be sure to tell the doctor if you have ever had an allergic reaction to iodine, IVP or catheterization dye, or shellfish. Depending on the nature of your previous reaction, the solution will have to be modified or simply not used.
The CT scan itself is simple and painless, and usually takes less than an hour to complete. Serious side effects are rare, but a temporary feeling of warmth and mild nausea are common after the contrast injection. After the examination, you will be able to resume your normal activities and diet. You should drink plenty of fluids for 24 hours after the examination to help flush out your system.
In some instances, your doctor may request that you have a nuclear scan. Although the name sounds a little unsettling, a nuclear scan involves only a small "tracer" dose of radioactive material, and is not dangerous. Once this tracer is injected into your system, it can be followed through your digestive organs as you lie directly underneath a large, flat Geiger counter. A nuclear scan is most often used to assess liver and gallbladder function. Other uses include measurement of stomach emptying and localization of intestinal bleeding. Nuclear scans require very little preparation.
X-ray, Ultrasound, CAT scan and Nuclear Scan exams require specialized equipment and highly trained technicians. They are usually performed in a hospital our specialized outpatient facility.
Who Performs The Exam?
In most cases, the examination will be performed by a specially trained technician who is expert in using the equipment. The radiologist may or may not be present depending on the circumstances. However, the radiologist will review the final films and proceed with an official evaluation.
How Do I Schedule My Test?
Our office can assist you in obtaining all the necessary information to schedule your examination with your local outpatient radiology department. Any special preparation instructions will be provided.
Preparing for Your Test
Careful preparation is an important part of any examination. Preparation instructions vary from test to test and will be provided by our office staff. In all instances, you should wear easily-removable and comfortable clothing. Leave girdles, valuables, high heels, and jewelry at home. Be sure that you fully understand what preparation is required of you so that a safe and accurate examination can be performed. If you do not, the examination may have to be repeated at a later date. If you have any questions, please ask. After Your Exam After your examination is completed, you will be able to immediately resume normal activities and diet. You should drink plenty of extra fluids for the first 24 hours to help flush your system. A word to the wise: If barium was used for your test, you might also wish to take a mild laxative such as an ounce of Milk of Magnesia after the x-ray. This helps eliminate the barium from your system. If this is not done, the barium can harden, much like plaster of Paris, making elimination quite difficult.
What About Side Effects?
There are no known side effects to health from ultrasound. Nuclear scans, CAT scans, and barium x-rays do expose your body to small amounts of radiation. However, the dose is quite low and felt to be generally safe. The exceptions would be pregnancy and breast feeding. Any woman who is pregnant, or thinks she might be, or is breastfeeding, should let her doctor know before scheduling the examination. Also, if you believe that you are allergic to iodine dyes and are scheduled for a CT scan, notify your doctor.
How Do I Get The Results?
Once the test is completed, the films are developed and analyzed by the radiologist who then sends us a written report. Your doctor will contact you after reviewing the results in the context of your case. This may take about a week, but most reports arrive sooner.
In addition to "scope" tests, imaging techniques such as barium x-rays, Ultrasound studies, CAT and Nuclear Scans are often requested to obtain information about the status of your digestive system. These tests are generally safe and well tolerated, but require proper preparation. You have an important role in making your examination a success. If you have any questions, again please ask.