HIDA Scan Explained: Hepatobiliary Scintigraphy for Cholecystitis and Bile Leaks

HIDA (also called cholescintigraphy) is a functional biliary test performed when ultrasound is equivocal or bile-flow physiology is being assessed. In acute cholecystitis, ultrasound typically shows gallstones, wall thickening, and pericholecystic fluid — usually sufficient. HIDA is reserved for cases where these findings are equivocal: sensitivity for acute cholecystitis > 95%, specificity > 90%. Findings: non-visualisation of the gallbladder at 60 minutes = cystic duct obstruction (acute cholecystitis); delayed visualisation at 4 hours = chronic cholecystitis. CCK-stimulated gallbladder ejection fraction (GBEF) < 35% supports biliary dyskinesia (a controversial diagnosis — Rome IV criteria emphasise functional gallbladder disorder). Post-cholecystectomy bile leak: tracer accumulates outside biliary tree. Sphincter of Oddi dysfunction: prolonged transit through common bile duct with delayed appearance in bowel. Radiation dose ~5–7 mSv. Preparation: fast 4–6 hours (empty gallbladder falsely fails to fill); avoid opioids (constrict sphincter of Oddi); recent parenteral nutrition or fasting > 24 hours may cause false non-filling (add morphine or CCK challenge).