HIDA scan

Hepatobiliary Iminodiacetic Acid (HIDA) Scan is a diagnostic imaging procedure used to evaluate the function and structure of the gallbladder and the bile ducts. A HIDA scan, also known as cholescintigraphy or hepatobiliary scintigraphy, involves the use of a radioactive tracer to visualize the bile-producing and transporting pathways within the liver, gallbladder, bile ducts, and small intestine. This test is particularly useful in diagnosing conditions such as gallstones, biliary atresia, and cholecystitis.

Procedure

During a HIDA scan, a radioactive tracer (technetium-99m-labeled hepatobiliary iminodiacetic acid) is injected into a vein in the patient's arm. This tracer is absorbed by the liver cells and then excreted into the bile. A special camera, called a gamma camera, detects the radiation emitted by the tracer and creates images of the bile ducts, gallbladder, and liver.

The patient may be asked to fast for a certain period before the test. In some cases, medication that stimulates the gallbladder may be administered to assess its function.

Indications

HIDA scans are indicated for patients with symptoms suggestive of gallbladder or bile duct disorders. These symptoms may include abdominal pain, jaundice, and unexplained nausea or vomiting. The scan can help in diagnosing:

• Gallstones: Detecting blockages in the bile ducts caused by stones.
• Cholecystitis: Assessing inflammation of the gallbladder.
• Biliary atresia: Evaluating infants with jaundice to check for blocked bile ducts.
• Bile leak: Identifying leaks from the bile ducts.

Interpretation

The results of a HIDA scan are interpreted by a radiologist or a nuclear medicine specialist. Normal results show the tracer moving smoothly from the liver into the gallbladder and then into the small intestine. Abnormal results may indicate a blockage in the bile ducts, poor functioning of the gallbladder, or other abnormalities.

Risks and Complications

The HIDA scan is generally considered safe. The amount of radiation exposure is low and not associated with significant risks. However, as with any procedure involving radioactive materials, it is not recommended for pregnant women. Allergic reactions to the tracer are rare.

Conclusion

The HIDA scan is a valuable diagnostic tool in the evaluation of hepatobiliary diseases. It provides critical information about the function and structure of the gallbladder and bile ducts, aiding in the diagnosis and management of various conditions.