Diagnostics
Gallbladder scan/HIDA scan
A gallbladder scan, also known as HIDA scan, cholescintigraphy, or hepatobiliary scintigraphy, is an imaging procedure. It uses a radioactive tracer and a scanning camera to evaluate the gallbladder and track bile flow from the liver to the small intestine.
The liver produces bile, a digestive fluid that helps break down fats in the food we eat. Bile is transported from the liver to the gallbladder through biliary ducts for storage. The gallbladder lies beneath the liver. It contracts and releases stored bile into the small intestine when we eat aiding in the digestion of fats.
The HIDA scan helps diagnose conditions and symptoms related to the biliary system. By observing the movement of the radioactive tracer, a HIDA scan can assess the proper functioning of various processes, such as bile flow and gallbladder contraction.
Who performs HIDA scan?
When would an individual need a HIDA scan?
A HIDA scan may be recommended by the doctor in the following situations:
- Severe abdominal pain, particularly on the right side, could indicate cholecystitis (gallbladder inflammation).
- Post-surgical pain or fever following gallbladder, upper gastrointestinal tract surgery, or liver transplant.
- Severe jaundice in newborns may suggest biliary atresia (blockage in the ducts that carry bile from the liver to the gallbladder).
- Assessment of the function of a biliary stent placed to address a blocked or partially blocked bile duct.
- Monitoring liver function after liver transplant surgery.
How is the HIDA scan done?
Preparing for the HIDA scan
- The patient will be asked to fast for four hours prior to the scan. However, may be allowed to drink clear liquids during this time.
- The doctor may advise the patient to stop taking certain medications and supplements before the scan temporarily.
- The patient should inform the doctor of all medications they are currently taking. It’s important to provide an accurate and complete list of medications, including prescription drugs, over-the-counter medications, herbal supplements, and vitamins.
- Wear comfortable clothing, preferably with no metal objects such as zippers or buttons, as they can interfere with imaging. The patient may be asked to change into a hospital gown before the procedure.
- In cases where there may be a possibility of pregnancy or if the patient is breastfeeding, it is crucial to inform the doctor. Nuclear medicine tests like the HIDA scan are generally not performed during pregnancy due to potential risks to the baby. The doctor will provide guidance and alternative options if needed.
During HIDA scan
- The patient will lie on the back on the exam table.
- A nurse or technologist will insert an IV catheter into a vein in the hand or arm to administer the radiotracer.
- The scanning camera will be positioned close to the belly.
- The scanning camera will take a series of images, either rotating around the patient or remaining in one position. It is important to remain very still during this time to ensure clear and accurate images.
- The patient may be asked to change positions between images as the technologist directs.
- After capturing the initial series of images, the patient may receive medication to stimulate the emptying of the gallbladder. This may cause some cramping in the upper belly. Additional images will be taken during this time.
- Once all the necessary images have been obtained, which may take up to four hours, the scan will be completed.
After the HIDA scan, depending on the circumstances, the patient may either be allowed to go home or return to the hospital room.
- It is important to ensure that the patient drinks plenty of fluids in the next 24 hours following the scan. This helps flush out the radiotracer from the body. Most of the radiotracer will be eliminated through urine or stool within a day.
- Remember to flush the toilet immediately after use and wash hands thoroughly with soap and water to maintain safety. The radiotracer’s radiation is very low, so there is no risk to people being around the patient after the scan.
- If breastfeeding, it is necessary to discard any pumped milk for 24 hours after the scan. This is because breast milk may contain radiation from the radiotracer, which could potentially harm the baby. It is advisable to pump and store extra breast milk before the scan or make alternative arrangements for the baby’s nutrition during that day.
A HIDA scan is a safe procedure with minimal risks, including:
- Allergic reaction to medicines containing radioactive tracers.
- Bruising at the injection site.
- Low radiation exposure, which is considered to be minimal and safe.
What type of results does the patient get from a HIDA scan?
The report from a HIDA scan provides detailed information about the flow of the radiotracer through the biliary system.
The doctor analyzes the results of the HIDA scan along with other tests, such as blood tests, to reach a final diagnosis.
The possible findings in a HIDA scan report may include the following:
- Normal: The radiotracer moved freely from the liver into the gallbladder and small intestine.
- Slow movement of radiotracer could indicate a blockage or obstruction, or impaired liver function.
- The absence of radiotracer in the gallbladder may indicate acute cholecystitis (gallbladder inflammation) caused by a blockage.
- Abnormally low gallbladder ejection fraction: The ejection fraction indicates how much bile the gallbladder can release after stimulation with medication. A lower-than-normal ejection fraction, below 30% to 35%, may suggest chronic cholecystitis.
- If the scan reveals radiotracer in areas outside the biliary system, it could indicate a bile duct leak.
It is important to remember that the doctor will explain the results to the patient and address any questions the patient may have.
References
- Mayo Clinic. HIDA scan. Available from: https://www.mayoclinic.org/tests-procedures/hida-scan/about/pac-20384701
- Cleveland Clinic. HIDA Scan. Available from: https://my.clevelandclinic.org/health/diagnostics/17099-hida-scan
- Cholescintigraphy (HIDA Scan). Available from: https://www.medicinenet.com/cholescintigraphy/article.htm
