A HIDA (Hepatobiliary Iminodiacetic Acid) scan is a diagnostic imaging procedure used to evaluate the gallbladder and bile ducts. Proper preparation for this procedure is important for accurate results and a smooth experience. Understanding these steps helps patients prepare.
Understanding the HIDA Scan
A HIDA scan is a nuclear medicine imaging procedure that uses a radioactive tracer. This tracer is injected into a vein and travels through the bloodstream to the liver, where it is absorbed and then excreted into the bile. The bile, along with the tracer, then moves into the bile ducts, the gallbladder, and eventually the small intestine.
The purpose of this scan is to assess the function of the gallbladder and the patency of the bile ducts. It helps diagnose conditions such as acute cholecystitis or blockages within the bile ducts. By tracking the tracer’s path, doctors observe how well the gallbladder fills and empties, indicating its functional health.
Key Preparatory Steps
Fasting is a key preparatory step for a HIDA scan. Patients should fast for four to six hours prior to the procedure. Do not fast for more than 12 to 24 hours, as prolonged fasting can lead to a false-positive result. Fasting ensures the gallbladder is in a relaxed, empty state, allowing it to fill with the radioactive tracer.
Fasting means refraining from all food and beverages, except clear water. Discuss all current medications with your doctor or the imaging center staff before the scan. Some medications, such as opioid pain relievers, can affect the gallbladder’s function and might need temporary adjustment or stopping. Patients should never discontinue any prescribed medication without explicit guidance from their healthcare provider.
Wear comfortable, loose-fitting clothing to your appointment. Avoid wearing jewelry or any metal objects, as these can interfere with the imaging equipment. Staying well-hydrated with water before the fasting period begins can help with the injection process and comfort.
Important Considerations Before Your Scan
Inform medical staff if you are pregnant, might be pregnant, or are breastfeeding. Due to the use of a radioactive tracer, precautions are necessary to protect both the patient and, in the case of pregnancy or breastfeeding, the baby. This allows the medical team to assess risks and determine the appropriate course of action.
Inform staff about any known allergies, particularly to medications or contrast agents. While a HIDA scan does not typically use iodine-based contrast material, disclosing all allergies helps ensure patient safety. Providing a medical history contributes to a safer and more effective scanning experience.
Mention any recent barium studies or other imaging procedures involving contrast agents. Residual contrast could interfere with the HIDA scan images, affecting the accuracy of the results. If a sedative is administered before the HIDA scan to help with anxiety or discomfort, patients should arrange for someone to drive them home afterward.
What to Expect During and After the Scan
During a HIDA scan, the radioactive tracer is injected intravenously, usually into a vein in the arm. After the injection, the patient will lie still on an imaging table while a special camera, called a gamma camera, records the movement of the tracer through the liver, bile ducts, and gallbladder. The scan typically takes about one to two hours, though it can sometimes extend longer if delayed images are required.
In some cases, a medication like cholecystokinin (CCK) may be administered during the scan to stimulate gallbladder contraction and assess its ejection fraction. This helps evaluate how effectively the gallbladder empties bile. Following the completion of the scan, patients can generally resume their normal activities and dietary habits unless otherwise instructed by their healthcare provider. It is also recommended to drink plenty of fluids after the scan to help excrete the radioactive tracer from the body.