Some other terms for this procedure are hepatobiliary scintigraphy, cholescintigraphy, or hepatobiliary scan. This is an imaging procedure, related to the field of nuclear medicine, which is used to observe the production and flow of the bile. 'Bile' is a digestive hormone that is secreted by the liver and helps in the breakdown of fats in the food that we ingest. This procedure creates the images of your hepatobiliary tract which includes liver, gallbladder, bile ducts, and small intestine. A HIDA scan uses a radioactive substance for this purpose.
When Is A HIDA Scan Done? Indications For A HIDA Scan
HIDA is scan is the imaging study of choice for the diagnosis of Cholecystitis. However, this scan may also aid in the diagnosis of other conditions such as:
- Obstruction of bile duct
- Bile leakage from the hepatobiliary tract
- Congenital diseases of bile duct such as 'biliary atresia'
- Cholelithiasis (gall stones)
- Gallbladder ejection fraction - measuring the rate at which bile is released
Preparations Before the Procedure
- Fasting - the patient is advised not to eat anything 3-4 hours before the procedure. It should be kept in mind that the recommendations vary according to the situation.
- Stop certain medication - certain drugs may interfere with HIDA scan. Doctor may ask you not to take any medication for a certain period of time. You should always tell your doctor if you're taking any medicines.
- Take certain medication - you may be given some medication before the procedure. These medicines help the doctor interpret the results of HIDA scan accurately. Whether you need to take this medicine or not, depends on the reason HIDA scan is being performed. In some cases, radioactive tracer or chemical is infused into the patient's body.
After The Procedure
Usually, the patient is able to lead his routine life right after the procedure. The radioactive tracer in the body takes a day or two to leave the body through urine. This is the reason doctors always advise the patients that they flush the toilet twice after urinating. Doctors recommend that you wash your hands thoroughly after the toilet and drink excess water throughout the day. Drinking more water helps the body in draining the radioactive tracer quickly out of the body.
The doctor (radiologist) may discuss the results of the HIDA scan right after the procedure. In most cases, the radiologist sends the results to the doctor, and the doctor discusses the outcomes of the procedure with the patient.
The results of the HIDA scan are based on the visualization of radioactive tracer in the biliary system. The possible results of HIDA scan are discussed below.
- Normal HIDA scan: The scan is labeled as normal if the radioactive tracer moves free within your hepatobiliary tract without any obstruction. No problems detected.
- Slow movement of radioactive tracer: The radioactive tracer may be seen moving slowly within the hepatobiliary tract. This indicates that there may be an obstruction, blockage, or the liver is not functioning properly.
- No tracer in the gallbladder: Absence of radioactive tracer in the gallbladder indicated acute inflammation of the gallbladder - Cholecystitis.
- Low ejection fraction: If the amount of radioactive tracer is low after leaving the gallbladder, this may point towards chronic inflammation of the gallbladder - chronic Cholecystitis.
- High ejection fraction: High ejection fraction is considered to be unpredictable. Other lab tests in conjunction with physical examination help in reaching the correct diagnosis.
- Radioactive tracer seen outside the hepatobiliary tract: This indicates that there is a leakage in the hepatobiliary tract.
This test aids in making the correct diagnosis. Not very often, but there are situations where HIDA scan is neither normal nor it shows any clear results. Doctors advise further testing in such cases.
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