Quick answer: a HIDA scan (hepatobiliary scan, or cholescintigraphy) follows a small amount of radioactive tracer as your liver makes bile and sends it to the gallbladder and the intestine. It helps diagnose acute gallbladder inflammation (cholecystitis), bile leaks and bile duct blockages, and with a medication called CCK it can measure how well your gallbladder empties (the ejection fraction). You need to fast for at least 4 hours, but usually not more than 24, and tell the team about any opioid pain medication. The scan usually takes 1 to 4 hours, occasionally with images the next day.
HIDA scans are usually ordered for people with upper right belly pain, and many arrive hungry and in discomfort. The test is painless, but it needs patience: much of it is lying still while the camera watches the bile flow.
What a HIDA scan shows
The tracer is taken up by the liver and released into the bile, just like bilirubin. By taking pictures over time, the camera shows whether bile flows normally from the liver, through the bile ducts, into the gallbladder and then into the small intestine.
Doctors use it to help diagnose:
- acute cholecystitis, a sudden inflammation of the gallbladder, often caused by a stone blocking its outlet
- functional gallbladder disorder (biliary dyskinesia), when the gallbladder does not empty well, using the ejection fraction test
- bile leaks, for example after gallbladder or other abdominal surgery
- blockages of the bile ducts
- biliary atresia in newborns, a blockage of the bile ducts
Gallstones themselves are usually seen best on ultrasound, which is often the first test. See [link: Abdominal Ultrasound: How to Prepare].
How to prepare
- Fast for at least 4 hours before the scan. Food in the stomach makes the gallbladder contract, so it may not fill with tracer.
- Do not fast for too long either. If you have not eaten for 24 hours or more, for example because you are in hospital, the gallbladder can be full of thick bile and may not fill. The team may give you a medication beforehand to empty it.
- Opioid pain medicines such as morphine can affect bile flow. Tell your doctor and the team about any pain medication you take; they may ask you to hold it for a few hours before the scan. Do not stop any medication on your own.
- Barium: avoid tests using barium in the 48 hours before the scan.
- Pregnancy and breastfeeding: always tell the team.
- Bring something to do, since the test can take several hours.
From the scanner room: [TU EXPERIENCIA: los fallos de preparación que más ves (pacientes que han desayunado, ingresados en ayunas desde hace días, analgésicos opioides) y cómo se resuelven.]
Step by step
1. The injection. A small IV is placed in your arm and the tracer is injected. You may feel a cold sensation.
2. Dynamic imaging. You lie on your back under the camera, usually for about 60 minutes, while it takes continuous pictures of your liver, gallbladder and intestine. You need to stay still. The camera comes close to your belly but does not touch you.
3. Extra steps, if needed:
- If the gallbladder does not appear, the team may take delayed images a few hours later, or give a small dose of morphine through the IV, which helps the tracer reach the gallbladder and can shorten the wait.
- Ejection fraction test: once the gallbladder is full, you may receive CCK (sincalide), a medication that makes the gallbladder contract, usually as a slow infusion over 60 minutes while the camera keeps recording. Some centers use a fatty drink instead.
- Very occasionally, you may need to come back for images up to 24 hours later.
From the scanner room: [TU EXPERIENCIA: cómo suele ir la infusión de CCK y qué sensaciones describen los pacientes; cuándo usáis morfina o imágenes tardías en tu servicio.]
What it feels like
The scan is painless. Lying still for an hour can be uncomfortable if you are in pain. If you receive CCK to empty the gallbladder, you may have slight abdominal cramping or nausea, which usually passes within minutes; tell the technologist if it bothers you. You will not be on the table the whole time if delayed images are needed.
How long does it take?
| Part | Typical time |
|---|---|
| Injection and dynamic imaging | About 60 minutes |
| Ejection fraction with CCK, if ordered | About 60 more minutes |
| Delayed images or morphine, if needed | Up to a few more hours |
| Whole test | Usually 1 to 4 hours; occasionally images up to 24 hours later |
After the scan
You can usually eat and return to normal activities right away. Drink plenty of water to help clear the tracer, which also leaves through the bowel.
Understanding the results
A radiologist or nuclear medicine physician interprets the scan and sends a report to your doctor. In general terms:
- Normal: the tracer flows from the liver into the gallbladder and the intestine within the expected time.
- Gallbladder not seen, even after delayed images or morphine: suggests the gallbladder outlet is blocked, as in acute cholecystitis.
- Tracer outside the bile system: suggests a bile leak.
- Tracer not reaching the intestine: may suggest a blockage of the bile ducts.
- Ejection fraction: with the standard 60-minute CCK infusion, a gallbladder ejection fraction of 38% or more is considered normal. A lower value suggests the gallbladder is not emptying well; your doctor will interpret it together with your symptoms.
Tips from the technologist
[TU EXPERIENCIA: 3 consejos propios. Ideas: pedir cita por la mañana para que el ayuno sea más fácil, llevar algo para comer después, avisar si el dolor aumenta durante la prueba.]
Frequently asked questions
Why can’t I eat before a HIDA scan?
Eating makes the gallbladder contract and empty, so it may not fill with tracer, which could look abnormal when it is not.
Is a HIDA scan painful?
No. The CCK medication can cause brief cramping or nausea, which passes quickly.
What is a normal gallbladder ejection fraction?
With the standard 60-minute CCK infusion recommended by the Society of Nuclear Medicine, 38% or higher is considered normal.
Can a HIDA scan show gallstones?
Not directly. It shows how bile flows; gallstones are best seen on ultrasound.
Do I need my gallbladder removed if the HIDA scan is abnormal?
Not necessarily. Your doctor and surgeon will consider the results together with your symptoms and other tests.
This article is for general information and does not replace advice from your doctor or nuclear medicine team. Do not stop medications without medical instructions.