Gallbladder X Rays
Gallbladder X Rays
Gallbladder x rays
Gallbladder x rays are diagnostic studies of the gallbladder (GB), a small pear-shaped sac that stores bile and is located under the liver . The study involves taking tablets containing iodine compounds a day before the x ray. The tablets are absorbed by the intestine, excreted by the liver and then concentrated in the gallbladder. In some clinics and hospitals the tablets are taken over a two day period, in hope of a better visualization of the gallbladder. This is known as a double-dose oral cholecystogram. This test was once the standard for diagnosing diseases of the GB; however, in recent years it is not often requested due to the advances in diagnostic ultrasound.
This test, also known as an oral cholecystogram or OCG, is usually ordered to help physicians diagnose disorders of the gallbladder, such as gallstones, inflammation, and tumors. The test is usually ordered when a gallbladder ultrasound has proved non-diagnostic. It is used in the investigation of patients complaining of upper abdominal pain after eating a fatty meal. Obese women over forty with a diet high in fat and low in fiber are at risk for gallstones. This test also measures gallbladder function, since the failure of the organ to visualize can signify a non-functioning or diseased gallbladder. The gallbladder may also not visualize if the bilirubin level is over four, and the study should not be performed under these circumstances. A CT scan, MRI (magnetic resonance imaging ), or an ERCP (endoscopic retrograde cholangio-pancreatography) would be done instead.
The physician must be notified if the patient is pregnant or allergic to iodine. Patients with a history of severe
kidney damage have an increased risk of side effects from this procedure. Ultrasound is commonly used instead of the x-ray examination when gallstones are suspected. Some people experience side effects from the contrast material (iodine tablets), especially diarrhea . During preparation for the test, patients should not use any laxatives . Diabetics should discuss the need for any adjustment in medication with their physician.
The exam is performed in the radiology department. The iodine tablets are purchased at a pharmacy or supplied by the hospital. The night before the test, patients swallow six tablets (one at a time) with plenty of water. If a double-dose OCG is requested, this will be done over a two day period.
The patient will be asked to put on a hospital gown. The x-ray technologist will take a preliminary or scout film to see if the gallbladder is well visualized. The patient is placed prone with the right side slightly raised to prevent superimposition of the spine. The first film should show all of the right side of the abdomen, from the lateral side of the spine down to the iliac crest (top of the pelvis). Tall thin patients will need to be turned more since the gallbladder tends to lie lower and closer to the spine than in shorter, heavier patients. If the gallbladder is well seen on the first film, the x-ray technologist or radiologist will take another film coned-down and centered directly on the gallbladder. At least one more film in an upright or a lateral decubitus position will be done, since gallstones tend to sink downward or float in the gallbladder, as compared to a tumor or polyp, which remains in the same position. The gallbladder can displace to a considerably lower position when the patient is upright, so the radiography technologist must take into account the bodily habitus (size and shape) of each individual patient.
The radiologist will review the x-rays and then take a series of coned-down (spot) films of the gallbladder with a fluoroscope (a special apparatus that projects the image onto a video monitor to be seen immediately). The radiologist may ask for another film to be taken 30 minutes after a fatty meal. The patient will be given a glass of egg nog or in some instances buttered toast and coffee or tea with cream. This meal will cause the gallbladder to contract and release bile, so the gallbladder should diminish in size on the post-fatty meal film (PFM). Delayed films may be taken if this doesn't occur. The exam usually takes one hour to complete and may be done in a hospital or a clinic that is certified to take x rays.
The day before the test, patients are instructed to eat a normal breakfast and lunch and a light fat-free dinner (no fried or fatty foods, cream, milk, or butter). The night before, six Telepaque pills (iodine tablets) are taken one at a time, five minutes apart, with a large glass of water. Only water or juice is permitted until midnight. After midnight no food or liquids are allowed until after the exam. In some instances the clinic or hospital may prefer that a double-dose OCG be routinely done. This involves taking the Telepaque tablets over a two-day period. The pills may be taken two at a time with each fat-free meal or all at once, depending on the routine requested by the radiology department.
No special care is required after the study.
There is a small chance of an allergic reaction to the contrast material. In addition, there is a low level of radiation exposure. X rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most experts feel that the risk is low compared with the benefits. Pregnant women and children are more sensitive to the risks of x rays, and the risk versus the benefits should be discussed with the treating physician. In some cases diarrhea or vomiting may occur. The x-ray technologist should be informed, since the gallbladder might not be well visualized.
A normal OCG will show a normal gallbladder. The gallbladder should visualize, and be free of any solid structures, such as stones, polyps, or tumors. It should empty freely with no obstruction after the PFM (post-fatty meal).
Abnormal results may show gallstones, tumors, or cholesterol polyps (a tumor growing from the lining that is usually non-cancerous). Typically stones will "float" or move around as the patient changes position, whereas tumors will stay in the same place.
Health care team roles
The radiography technologist works closely with the nurses (if the patient is hospitalized) to make sure the patient is given the Telepaque tablets and follows a fat-free diet. Any diarrhea or vomiting must be noted and the radiology department advised. The x-ray technologist must also be aware of the bilirubin level, which could indicate liver disease and a non-functioning gallbladder. In the case of a high bilirubin level the exam would not be done. All x-ray technologists must be certified and registered with the American Society of Radiologic Technologists or an equivalent association, depending on where the exam is being done.
Patients must understand the importance of taking the contrast tablets and following a fat-free diet. All women of child-bearing age should be aware of the dangers of x rays to a fetus, and will be protected as much as possible without obstructing the image of the gallbladder.
Bile —A yellow-green liquid produced by the liver, which is released through the bile ducts into the small intestines to help digest fat.
Bilirubin —A reddish-yellow pigment formed from the destruction of red blood cells, and metabolized by the liver. Levels of bilirubin in the blood increase in patients with liver disease or blockage of the bile ducts.
Body habitus —The size and shape of a person's body.
ERCP —An endoscopic retrograde cholangio-pancreatography. A flexible telescope is placed through the nose or mouth into the stomach, upper intestine and then the common bile duct to visualize the GB and pancreas. This is done when there is poor visualization of the gallbladder on an ultrasound examination, CT scan or OCG.
Ultrasound —A noninvasive procedure based on changes in sound waves of a frequency that cannot be heard, but respond to changes in tissue composition. Patients must be fasting for at least six hours but no contrast material is given. There is no radiation used in an ultrasound exam, so it is the exam of choice for the diagnosis of stones in the gallbladder, but is less accurate in diagnosing stones in the bile ducts. Gallstones as small as 2 mm can be identified.
Levenson, Deborah E. and Hans Fromm. "Oral Cholecystogram." In Hepatology: A Textbook of Liver Disease, edited by David Zakim and Thomas D. Boyer et al. Philadelphia: W.B. Saunders Company. 1996, p.1883.
Zeaman, Robert K. "Oral Cholecystography." In Bockus Gastroenterology, edited by William S. Haubrich et al. Philadelphia: W.B. Saunders Company. 1995, pp. 208-211.
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Gallstones from NIDDK. <http://www.niddk.nih.gov/health/digest/pubs/gallstns/gallstns.htm>.
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Lorraine K. Ehresman