Biliary Scan with EF 95% Does NOT Rule Out Biliary Atresia
A hepatobiliary scan (HIDA/mebrofenin scan) showing gallbladder ejection fraction of 95% does NOT exclude biliary atresia, as this test measures gallbladder contractility rather than biliary patency, and the critical diagnostic finding for biliary atresia is absence of intestinal excretion at 24 hours, not ejection fraction. 1, 2
Understanding the Diagnostic Confusion
The ejection fraction (EF) of 95% you're referencing measures gallbladder contractility in response to cholecystokinin stimulation, which is used to diagnose functional gallbladder disease in adults and older children 3. This is fundamentally different from what hepatobiliary scintigraphy evaluates in suspected biliary atresia 1, 4.
Correct Interpretation of Hepatobiliary Scintigraphy for Biliary Atresia
Key Diagnostic Parameters
For biliary atresia diagnosis, the critical findings on Tc-99m mebrofenin scan are 4:
- Hepatic uptake at 5 minutes: Assesses liver parenchymal function
- Persistent hepatic retention at 24 hours: Present in 100% of biliary atresia cases 4
- Absence of intestinal excretion at 24 hours: The most specific finding, present in 78.6% of biliary atresia versus only 38.9% of neonatal hepatitis (p = 0.007) 4
The absence of radiotracer excretion into the intestines at 24 hours is the diagnostic criterion for biliary atresia, not ejection fraction. 4
Critical Limitations of Hepatobiliary Scintigraphy
Why This Test Has Limited Utility
Recent comprehensive reviews demonstrate that hepatobiliary scintigraphy is NOT useful for diagnosing biliary atresia 1. The major limitations include:
- Poor specificity: Neonatal hepatitis can also show non-excretion (38.9% of cases) 4
- Cannot differentiate between biliary atresia and severe neonatal cholestasis from other causes 1
- False positives are common in any severe cholestatic condition 1
Recommended Diagnostic Approach
First-Line Imaging
Ultrasound is the primary diagnostic tool for biliary atresia, not hepatobiliary scintigraphy 1, 2. Key ultrasound findings include:
- Triangular cord sign: Highest sensitivity and specificity 2
- Abnormal gallbladder: Small, absent, or irregular walls 2
- Hepatic artery enlargement 2
- Presence of cysts at porta hepatis 2
Critical Caveat
A normal ultrasound does NOT rule out biliary atresia 1, 2. When ultrasound is equivocal or normal but clinical suspicion remains high, proceed to:
- Percutaneous cholecysto-cholangiography or endoscopic retrograde cholangiopancreatography for direct biliary visualization 1
- Percutaneous liver biopsy: Shows characteristic periportal fibrosis and bile duct proliferation 1
Clinical Context Matters
When to Suspect Biliary Atresia
The diagnosis should be considered in infants with 5:
- Persistent conjugated hyperbilirubinemia beyond 2-3 weeks of life
- Acholic (pale) stools
- Dark urine
- Hepatomegaly
Urgency of Diagnosis
Time is critical: Kasai portoenterostomy must be performed before 8 weeks of age for optimal outcomes, with more than one-third of children achieving survival when operated early 5. Delayed diagnosis leads to progressive biliary cirrhosis and liver failure 5.
Bottom Line
Your question about "EF 95%" suggests a misunderstanding of what test was performed or how to interpret it. If this was truly a hepatobiliary scan for suspected biliary atresia, the ejection fraction is irrelevant—you must evaluate intestinal excretion at 24 hours 4. However, given the poor diagnostic utility of hepatobiliary scintigraphy for biliary atresia 1, ultrasound with specific signs, followed by direct cholangiography and/or liver biopsy, represents the appropriate diagnostic pathway 1, 2.