Gallbladder Function Scan (HIDA with Medication)

What it is

Ultrasound can show a gallbladder full of stones; it cannot show whether the gallbladder works. This scan can, because it images the bile itself in motion. A small amount of a radioactive tracer is injected into a vein, the liver pulls it out of the blood the way it pulls out bile components, and a gamma camera records where it goes over the following hour or so: into the liver, down the bile ducts, into the gallbladder, and out into the intestine. A duct that is blocked shows as a compartment the tracer never reaches.

The pharmacologic part is what separates this code from a plain hepatobiliary scan. After the first series of images, the technologist gives a medication that makes the gallbladder contract, and imaging continues. That turns the study from anatomy into a function test: the fraction of tracer the gallbladder expels when told to is a number the radiologist reports, and poor squeezing can itself be the explanation for recurring pain in someone whose ultrasound looked unremarkable.

Why it is done

• To test whether the gallbladder empties properly, in someone with gallbladder-type pain and no stones on ultrasound
• To look for a blocked cystic duct, which is the finding behind acute gallbladder inflammation
• To investigate persisting pain after gallbladder surgery, or to check for a bile leak
• To trace bile flow when the question is whether the ducts are open all the way to the intestine

What to expect

You will be asked to fast beforehand — a gallbladder that has just been emptied by a meal cannot be tested — and to report any medications, particularly opioids, which affect bile flow. The tracer goes in through an IV. Then you lie still under the camera in stretches, which is the tiring part; the whole appointment commonly runs one to four hours, and occasionally you are asked back for a late image. When the contraction drug is given, some people feel abdominal cramping, nausea or an urge to move their bowels for a few minutes. It passes. The tracer leaves the body on its own afterward.

Questions worth asking

• Is the radiopharmaceutical charged as a separate line item from the imaging, and is the contraction drug a third?
• If the scan runs long or delayed images are needed, is that billed as additional imaging?
• Is this a hospital nuclear medicine department or a freestanding imaging center, and is the nuclear medicine physician reading it in my network?
• If the gallbladder is not visualized and the study is stopped early, is it still billed at the full rate?