Ultrasound of the Abdomen. Ultrasound is a simple, rapid, and noninvasive imaging technique. It is the diagnostic method most frequently used to detect gallstones and is the method of choice for detecting acute cholecystitis. If possible, the patient should not eat for 6 or more hours before the test, which takes only about 15 minutes. During the procedure, the doctor can check the liver, bile ducts, and pancreas, and quickly scan the gallbladder wall for thickening (characteristic of cholecystitis).
How well ultrasound can help in the diagnosis varies based on the patient's situation:
- Ultrasound accurately detects gallstones as small as 2 mm in diameter. Some experts recommend that the test be repeated if an ultrasound does not detect stones, but the health care provider still strongly suspects gallstones.
- Air in the gallbladder wall may indicate gangrene.
- Ultrasound does not appear to be very useful for identifying cholecystitis in patients who have symptoms but do not have gallstones.
- Ultrasound is also not as accurate for identifying common bile duct stones or imaging the cystic duct. Nevertheless, normal ultrasound results, along with normal bilirubin and liver enzyme tests are very accurate indications that there are no stones in the common bile duct.
Endoscopic Ultrasound. In an ultrasound variation called endoscopic ultrasound (EUS), the physician places an endoscope (a thin, flexible plastic tube containing a tiny camera) into the patient's mouth and down the esophagus, stomach, and then the first part of the small intestine. The tip of the endoscope contains a small ultrasound transducer, which provides "close-up" ultrasound images of the anatomy in the area. EUS is useful when the health care provider suspects common bile duct stones, but they are not seen on a regular ultrasound and the patient is not clearly ill. However, if common duct stones are detected, they cannot be removed using this method.
X-Rays. Standard x-rays of the abdomen may detect calcified gallstones and gas. Variations include oral cholecystography or cholangiography.
- In oral cholecystography, the patient takes a tablet containing a dye the night before the test. The dye fills the gallbladder, and x-ray images are taken the next day. The test has largely been replaced by ultrasound; however, it may be useful in some cases for determining the structural and functional status of the gallbladder, often before nonsurgical procedures.
- In cholangiography, a dye is injected into the bile duct and x-rays are used to view the duct. It is typically used during operations to provide a clear image of the biliary tract.
Cholescintigraphy (Also Called Gallbladder Radionuclide Scan or HIDA scan). Cholescintigraphy, a nuclear imaging technique, is more sensitive than ultrasound for diagnosing acute cholecystitis. It is noninvasive but can take 1 - 2 hours or longer. The procedure involves the following steps:
- A tiny amount of a radioactive dye is injected intravenously. This material is excreted into bile.
- The patient lies on a table under a scanning camera, which detects gamma (radioactive) rays emitted by the dye as it passes from the liver into the gallbladder.
- The test can take up to 2 hours, because each image takes about a minute, and images are taken every 5 -15 minutes.
If the dye does not enter the gallbladder, the cystic duct is obstructed, indicating acute cholecystitis. The scan cannot identify individual gallstones or chronic cholecystitis.
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Review Date: 06/10/2010
Reviewed By: Reviewed by: Harvey Simon, MD, Editor-in-Chief, Associate Professor
of Medicine, Harvard Medical School; Physician, Massachusetts
General Hospital. Also reviewed by David Zieve, MD, MHA, Medical
Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
