What test evaluates the ejection fraction of the gallbladder when it's slow?

Cholecystokinin-Cholescintigraphy (CCK-CS) is the Test for Evaluating Slow Gallbladder Ejection Fraction

The test that shows the ejection fraction of the gallbladder when it's slow is cholecystokinin-cholescintigraphy (CCK-CS), also known as a HIDA scan with CCK stimulation. 1

How CCK-CS Works

CCK-CS provides a physiologic, noninvasive, and quantitative method for assessing gallbladder contraction and calculating the gallbladder ejection fraction (GBEF). The procedure involves:

1. Administration of a Tc-99m-labeled HIDA (hepatobiliary iminodiacetic acid) radiotracer that is taken up by the liver and excreted into the biliary system
2. Accumulation of the radiotracer in the gallbladder
3. Stimulation of gallbladder emptying with cholecystokinin (CCK)
4. Calculation of the GBEF based on the percentage of radiotracer expelled from the gallbladder

Standardized Protocol

According to consensus guidelines, the standardized protocol for CCK-CS includes:

• Patient preparation: Fasting for at least 4-6 hours (preferably overnight)
• Medication restrictions:
  • Opiates and anticholinergics withheld for 48 hours
  • Other medications affecting gallbladder contraction (nifedipine, indomethacin, octreotide, etc.) withheld for 24 hours
  • Avoidance of nicotine and alcohol
• Procedure:
  • HIDA radiotracer injection and initial imaging for up to 60 minutes
  • Sincalide (synthetic CCK) infusion at 0.02 μg/kg over 60 minutes
  • Dynamic imaging (1 image per minute) during infusion
  • GBEF calculation at 60 minutes

Interpretation of Results

• Normal GBEF: ≥38% 1
• Abnormal GBEF: <38% (suggesting gallbladder dysfunction)

Clinical Applications

CCK-CS is primarily used to evaluate patients with:

• Upper abdominal pain thought to be biliary in origin
• Normal appearing gallbladder on ultrasound (no stones or wall thickening)
• Suspected functional gallbladder disorder (FGBD)

Advantages Over Other Techniques

While ultrasound is typically the first-line imaging for gallbladder assessment, it cannot evaluate functional aspects. CCK-CS has several advantages:

• Provides functional assessment of gallbladder contractility
• Quantifies the ejection fraction precisely
• Helps identify functional gallbladder disorders in patients with normal anatomical imaging

Important Considerations

• The test should be performed on an outpatient basis, not during acute illness or hospitalization
• A standardized protocol is critical for reliable results
• The primary indication is for well-selected patients with suspected functional gallbladder disorder
• An abnormal GBEF should be interpreted in the appropriate clinical context

Alternative Methods

While 3D and 4D ultrasound techniques have been studied for calculating GBEF and show good correlation with HIDA scanning 2, CCK-CS remains the gold standard for quantifying gallbladder ejection fraction and is the most widely validated technique for this purpose.