My doctor wants me to have an ejection fraction test on my gallbladder. What is this, and what should I expect?

L.

Gallbladder-related symptoms are usually caused by stones blocking the cystic duct that drains the gallbladder. Patients feel upper abdominal or right upper abdominal pain, usually worsening over 15 to 30 minutes and lasting for up to several hours. The pain may also radiate to the right shoulder blade. Often there is severe nausea and vomiting. These episodes, known as biliary colic, often occur after meals and late at night.

Generally, an ultrasound of the abdomen will detect the gallstones. However, in some cases, there are no stones found in the gallbladder, a condition termed acalculous biliary pain (ABP). Patients with ABP tend to be young women. While the cause of ABP is unknown, one theory is that microscopic stones are present (too small to be seen on ultrasound, yet big enough to obstruct the cystic duct). Another theory is that the pain stems from an abnormality in the gallbladder muscle, which affects the way that it empties.

The test used to diagnose ABP is known as gallbladder ejection fraction. In this exam, a radioactive marker is injected into the patient and the marker is then taken up by the liver and gallbladder. A hormone, known as CCK, is then given via IV to stimulate the gallbladder to contract and empty. The size of the gallbladder is measured both before and after the CCK is given. The amount of the marker that leaves the gallbladder is called the ejection fraction.

In people with normal gallbladders, the ejection fraction ranges between 35-75 percent. Patients who suffer from bouts of biliary pain and have lower ejection fraction readings are assumed to have ABP. Studies have shown that surgical removal of the gallbladder (cholecystectomy) helps ABP patients more than 90 percent of the time. When gallbladders removed from such patients are examined, most show the signs of chronic inflammation typically seen in gallbladders that do contain stones.