HIDA Scan

Also known as hepatobiliary imaging, cholescintigraphy, or gallbladder nuclear scanning, the HIDA scan obtains images of the hepatobiliary system to determine the patency of the cystic and common bile ducts through noninvasive scanning. The scanning is accomplished through injection of iminodiacetic acid analogues (IDAs) labeled with teclmetium-99m (99mTc). This test also evaluates gallbladder emptying.

Purpose

• To diagnose gallbladder disorders and determine degree of patency
• To diagnose acute and chronic cholecystitis
• To evaluate the patency of the biliary enteric bypass
• To assess obstructive jaundice in combination with radiography or ultrasonography

Patient preparation

• Explain to the patient that this test detects inflammation or obstruction of the gallbladder and its ducts.
• Tell him who will perform the test and where and that it takes about 90 minutes.
• Inform the patient that he'll receive an I.V. injection of a radionuclide. Tell him the needle insertion and the tourniquet may cause some discomfort.
• Explain that the radionuclide will be eliminated from the body within 6 to 24 hours.
• Inform the patient that repeat pictures may be taken up to 24 hours after the injection.
• Ask a female patient if she is pregnant.
• Ensure that the patient has no allergies to the media used, that he has fasted for 2 to 6 hours before the scan, and that he can comply with activity restriction during the scan.
• Ask the patient to remove all jewelry and metallic objects and to put on a gown and void before the test.
• Explain to the patient that sincalide may be given before the test to promote gallbladder contraction and emptying.

Procedure and posttest care

• Immediately after the radionuclide is injected I.V., the right quadrant of the abdomen is scanned while the patient is in a supine position; images are taken every 5 minutes for the first 30 minutes, then every 10 minutes for the next 30 minutes.
• Delayed views may be taken after 2, 4, and 24 hours if the gallbladder can't be visualized.
• If the gallbladder can't be visualized, morphine may also be given I. V. during the study to initiate spasms of Oddi's sphincter in an effort to move the radionuclide into the gallbladder.
• Monitor vital signs at baseline and every 15 to 30 minutes.
• Observe the patient carefully for up to 60 minutes after the study for a possible hypersensitivity reaction.
• Advise the patient to drink plenty of fluids, unless contraindicated, for 24 to 48 hours to eliminate the radionuclide from the body. Also tell him to flush the toilet immediately after each voiding and to wash his hands with soap and water.
• Rubber gloves should be worn by caregivers every time urine is discarded after the procedure. Gloves should be considered nuclear waste and disposed of appropriately.
• The patient may resume a regular diet after the test, unless contraindicated.

Precautions

• This test is generally contraindicated during pregnancy or lactation because it exposes the fetus or infant to radiation.
• Personnel involved should also be aware of the risks and precautions of this radioactive test.

Normal Findings

A normal HIDA scan shows the gallbladder to be normal in size, shape, and function; cystic and common bile ducts are patent.

Abnormal findings

Images may demonstrate acute or chronic cholecystitis, or common bile duct obstruction.

Interfering factors

• Patient's inability to remain still during the procedure
• Failure to observe pretest restrictions
• Presence of barium in GI tract (possible poor imaging)
• Bilirubin levels ≥30mg/dl (decrased hepatic uptake)
• Fasting more than 24 hours, total parenteral nutrition, or alcoholism (decreased hepatic uptake)