The gallbladder, a small organ beneath the liver, plays a part in the digestive system. To assess its performance, medical professionals may measure its “ejection fraction.” This measurement offers insight into how effectively the gallbladder functions in releasing bile, a digestive fluid.
The Gallbladder’s Function
The liver produces bile, a greenish-yellow fluid that aids in fat digestion. About half of the bile produced by the liver is stored and concentrated within the gallbladder between meals. When food, particularly fatty meals, enters the small intestine, the gallbladder contracts. This action releases the stored bile into the small intestine to help break down fats. Bile salts within the bile emulsify large fat globules into smaller droplets, making them easier for digestive enzymes to process and absorb.
What Gallbladder Ejection Fraction Measures
Gallbladder ejection fraction (GEF) quantifies the percentage of bile the gallbladder expels into the small intestine in response to a stimulus. A higher ejection fraction suggests more vigorous contraction and emptying, while a lower one indicates reduced contractile strength.
Measuring Ejection Fraction
Gallbladder ejection fraction is typically measured using a hepatobiliary iminodiacetic acid (HIDA) scan, also known as cholescintigraphy. During this procedure, a small amount of a radioactive tracer is injected into a vein, usually in the arm. This tracer travels through the bloodstream to the liver, where it is absorbed and then secreted into the bile. The tracer then flows with the bile into the gallbladder and, eventually, into the small intestine.
A special camera captures images as the tracer moves through the biliary system, allowing healthcare providers to visualize the gallbladder’s filling and emptying. To stimulate contraction, a hormone called cholecystokinin (CCK) or a fatty meal is administered. CCK causes the gallbladder to squeeze and release bile, mimicking the body’s natural response to food. By monitoring the tracer’s concentration over time, the percentage of bile ejected can be calculated. The entire process usually takes about one to two hours, depending on the individual’s response.
Understanding Ejection Fraction Results
Interpreting GEF results involves comparing the calculated percentage to established ranges. A normal gallbladder ejection fraction is generally considered to be above 30% to 38%, though specific thresholds can vary slightly between institutions. A low ejection fraction, typically below 35%, suggests that the gallbladder is not contracting adequately. This reduced emptying is often described as a hypokinetic gallbladder or can indicate a condition like biliary dyskinesia. While a low ejection fraction is more commonly associated with symptoms, a very high ejection fraction, sometimes defined as 80% or higher, is also recognized as potentially significant. This hyperkinetic state means the gallbladder is contracting too forcefully or frequently.
What Abnormal Results Mean
An abnormally low gallbladder ejection fraction often means the gallbladder does not empty bile effectively. This can lead to symptoms such as pain in the upper right abdomen, particularly after eating fatty foods. Other common symptoms include nausea, bloating, and discomfort. This condition, where the gallbladder’s motility is impaired without the presence of gallstones, is known as biliary dyskinesia. It can also be associated with chronic cholecystitis, which is long-term inflammation of the gallbladder. In some cases, a very high ejection fraction, or hyperkinetic gallbladder, can also cause similar symptoms due to overly intense contractions. When an abnormal ejection fraction is identified and correlates with a patient’s symptoms, healthcare providers will consider next steps. These may involve lifestyle adjustments, further diagnostic tests to rule out other conditions, or, in many instances, surgical removal of the gallbladder (cholecystectomy) to alleviate discomfort.