Oral Cholecystogram (cont.)
Barbara K. Hecht, PhD
Dr. Barbara Kaiser-McCaw Hecht is Director of Hecht Associates, Inc., consultants in Medical Genetics based in Jacksonville, Florida. Dr. Hecht is a Diplomat of the American Board of Medical Genetics both in Clinical Cytogenetic (Chromosome Genetics) and Medical Genetics (Genetic Counseling). Dr. Hecht attended Stanford University from which she received a BA and an MA in Biology.
Frederick Hecht, MD, FAAP, FACMG
Frederick Hecht, MD, lives in Scottsdale, Arizona. Dr. Hecht is a Pediatrician and Medical Geneticist and is certified by both the American Boards of Pediatrics and Medical Genetics. Dr. Hecht was born and raised in Baltimore and attended Dartmouth College in Hanover, N.H. and the Sorbonne at the University of Paris receiving his BA degree cum laude with distinction from Dartmouth.
In this Article
- What is an oral cholecystogram (OCG)?
- How is an oral cholecystogram done?
- What are the risks of an oral cholecystogram?
- When is an oral cholecystogram useful?
How is an oral cholecystogram done?
For an OCG, the patient takes iodine-containing tablets by mouth for one night or two nights in a row. The iodine is absorbed from the intestine into the bloodstream, removed from the blood by the liver, and excreted by the liver into the bile. The iodine, together with the bile, is highly concentrated in the gallbladder. Iodine is used in an OCG because it is dense and radioopague (stops x-rays). It outlines the gallstones that are radiolucent (x-rays pass through them) and that are usually invisible on x-ray.
The bile ducts themselves cannot be seen on the x-ray in an OCG because the iodine is not concentrated in the ducts. Therefore, any gallstones lodged in the ducts will go undetected on OCG.
Failure to visualize the gallbladder on an OCG may occur for one of two reasons. First, a gallstone may have obstructed the cystic duct and prevented the iodine-containing bile from entering the gallbladder. Second, inflammation of the gallbladder -- usually due to gallstones -- may have interfered with the gallbladder's ability to concentrate bile and iodine. Whichever the cause, failure to visualize the gallbladder on an OCG strongly suggests a diseased gallbladder.
What are the risks of an oral cholecystogram?
The risks of an oral cholecystogram are few. One, of course, is the radiation. However, in an OCG there is a relatively small amount of radiation from the x-rays.
Another risk involves the iodine. Some people are allergic to iodine. Fortunately, most people who are allergic know that they are, and therefore do not undergo the test.
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