A Hepatobiliary Iminodiacetic Acid (HIDA) scan is an imaging procedure used to evaluate the function of the liver, gallbladder, bile ducts, and small intestine. This test uses a radioactive tracer that flows with the bile to track the digestive fluid’s path through your system. While any medical scan can cause worry, the HIDA scan is generally not painful, though temporary discomfort may occur during specific stages. Understanding the steps involved helps manage anxiety about potential physical sensations.
Preparing for the HIDA Scan
Proper preparation ensures the scan accurately reflects your biliary system’s function. Physicians instruct patients to fast for a minimum of four hours before the procedure. Fasting is important because eating causes the gallbladder to contract and empty, which interferes with the tracer filling the organ.
Patients should not fast for more than 24 hours, as prolonged fasting can also prevent the gallbladder from filling properly, leading to inaccurate results. Discuss all current medications with the ordering physician, especially opioid or morphine-based pain relievers. These medications must usually be withheld for at least six hours before the scan, as they can cause a bile duct spasm that mimics a blockage.
For the test, you will be asked to change into a hospital gown. Wear comfortable, loose-fitting clothing and remove all metal objects and jewelry, as these can interfere with the imaging equipment.
Understanding the Physical Sensations
The HIDA scan begins when a technologist inserts an intravenous (IV) line into a vein in your arm or hand. The initial needle stick for the IV is usually the only moment of sharp sensation you will feel during the entire procedure. Once the IV is securely in place, the radioactive tracer, which is a liquid called a radiopharmaceutical, is injected through the line.
The injection of the tracer itself is not felt, as it is a small volume of liquid moving through the IV. You will then lie on your back on an imaging table while a specialized camera, called a gamma camera, is positioned over your abdomen. The main physical challenge during the imaging phase is remaining still on the table for the duration of the scan, which can last anywhere from one to four hours depending on the protocol.
Medication Administration
A specific part of the procedure that may cause temporary discomfort is the administration of a medication to stimulate your gallbladder. If your doctor needs to measure your gallbladder’s ability to contract, a drug like cholecystokinin (CCK), also known as sincalide, may be injected. CCK causes the gallbladder to squeeze, and this action can lead to temporary abdominal cramping, nausea, or a reproduction of the upper abdominal pain.
In some cases, if the gallbladder does not visualize properly after the initial tracer injection, the medical team may administer morphine to confirm a diagnosis. Morphine works by causing the sphincter of Oddi, a muscle that controls bile flow, to contract, which forces the tracer into the gallbladder if the duct is open. This pharmacological intervention can also induce mild, temporary nausea or a brief feeling of discomfort. These sensations are closely monitored by the attending staff and are generally short-lived, subsiding quickly after the medication has been administered.
Post-Scan Expectations
As soon as the imaging is complete, the technologist will remove the IV line. You can immediately resume your normal diet and activities, including driving, as no sedation is used. The small amount of radioactive tracer used will naturally pass out of your body over the next day or two.
To help flush the remaining tracer, drink plenty of water and other fluids in the 24 hours following the scan. It is also recommended to flush the toilet right after use and wash your hands thoroughly to minimize exposure. The amount of radiation exposure is very small, and it is safe to be around other people.
You will not receive the final diagnostic report immediately. The images and data are reviewed by a radiologist or nuclear medicine physician who prepares a detailed report. The final results are sent to the healthcare provider who ordered the test, and they will discuss the findings and next steps with you during a follow-up appointment.