Acute Cholecystitis HIDA Scan
Understand Acute Cholecystitis HIDA Scan in Biliary tract, liver, gallbladder, and small bowel HIDA Scan imaging, what it means, and next steps.
30-Second Overview
Normal hepatic uptake and biliary duct visualization with absent gallbladder filling indicates cystic duct obstruction, the hallmark of acute cholecystitis. Morphine augmentation can improve diagnostic accuracy. Rim sign (increased rim activity around gallbladder fossa) suggests gangrenous cholecystitis.
HIDA scan is the gold standard for diagnosing acute calculous cholecystitis. It has >95% sensitivity and specificity when properly performed. The scan visualizes cystic duct obstruction, which is the primary pathophysiologic event in acute cholecystitis. Early diagnosis allows prompt surgical intervention, preventing complications such as gallbladder gangrene, perforation, and peritonitis.
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Imaging Appearance
HIDA Scan FindingNormal hepatic uptake and biliary duct visualization with absent gallbladder filling indicates cystic duct obstruction, the hallmark of acute cholecystitis. Morphine augmentation can improve diagnostic accuracy. Rim sign (increased rim activity around gallbladder fossa) suggests gangrenous cholecystitis.
Clinical Significance
HIDA scan is the gold standard for diagnosing acute calculous cholecystitis. It has >95% sensitivity and specificity when properly performed. The scan visualizes cystic duct obstruction, which is the primary pathophysiologic event in acute cholecystitis. Early diagnosis allows prompt surgical intervention, preventing complications such as gallbladder gangrene, perforation, and peritonitis.
Understanding Acute Cholecystitis HIDA Scan
Acute cholecystitis is inflammation of the gallbladder, most commonly caused by cystic duct obstruction by a gallstone. This obstruction prevents bile from entering or leaving the gallbladder, leading to increased pressure, inflammation, and potential ischemia. If untreated, it can progress to gangrene, perforation, and life-threatening peritonitis.
HIDA (hepatobiliary iminodiacetic acid) scintigraphy is the definitive imaging test for diagnosing acute cholecystitis. Unlike ultrasound which shows anatomical findings (gallbladder wall thickening, pericholecystic fluid, stones), HIDA scan demonstrates the functional consequence of cystic duct obstruction: the failure of the radiotracer to enter the gallbladder despite normal liver uptake and biliary duct visualization.
Normal hepatic uptake with prompt biliary duct visualization but absent gallbladder filling (with or without morphine augmentation) confirms cystic duct obstruction and acute cholecystitis with ＞95% accuracy
How HIDA Scan Diagnoses Acute Cholecystitis
The scan relies on normal hepatobiliary physiology:
Normal sequence:
- Tracer injection: Technetium-99m mebrofenin or disofenin injected IV
- Hepatic uptake: Liver extracts tracer from blood (5-10 minutes)
- Biliary excretion: Tracer secreted into bile ducts (10-20 minutes)
- Gallbladder filling: Tracer enters gallbladder via cystic duct (within 30-60 minutes)
- Intestinal passage: Tracer enters small bowel (within 60 minutes)
Acute cholecystitis pattern:
- Normal liver uptake: Hepatic function preserved
- Normal bile ducts: Common duct and hepatic ducts fill
- Absent gallbladder: No tracer enters gallbladder despite normal ducts
- Intestinal visualization: Bowel activity present (rules out complete biliary obstruction)
Pathophysiology: A stone obstructs the cystic duct, creating a one-way valve effect. Bile cannot enter the gallbladder, but gallbladder secretions continue, increasing pressure and causing inflammation.
Highest accuracy with morphine augmentation
Correctly rules out healthy patients
Annual new cases
Imaging Patterns
Classic Acute Cholecystitis
Typical findings:
- Prompt hepatic uptake: Liver visualizes normally
- Prompt biliary duct filling: Common bile duct and hepatic ducts seen
- Non-visualized gallbladder: No gallbladder activity at 60 minutes
- Normal intestinal activity: Small bowel fills normally
- Cystic duct obstruction: Implied by above pattern
Morphine augmentation:
- Morphine (0.04 mg/kg IV) increases sphincter of Oddi tone
- Diverts tracer toward gallbladder
- Improves sensitivity to ＞98%
- Gallbladder should visualize within 30 minutes after morphine if patent
Gangrenous Cholecystitis
Severe inflammation may show:
- Rim sign: Increased pericholecystic activity due to inflammation
- Late gallbladder visualization: Partial obstruction with delayed filling
- Poor hepatic uptake: If patient severely ill
The rim sign is highly specific for gangrenous cholecystitis and indicates urgent surgical intervention.
Acalculous Cholecystitis
Without stones:
- Same imaging pattern as calculous cholecystitis
- Typically occurs in critically ill patients
- Associated with fasting, TPN, trauma, sepsis
- Higher complication rate due to delayed diagnosis
Chronic Cholecystitis
Longstanding inflammation:
- Delayed gallbladder filling (1-4 hours)
- Reduced gallbladder ejection fraction
- May contract poorly with CCK stimulation
- Differentiated from acute by eventual visualization
Clinical Scenario
Normal HIDA Scan
Prompt hepatic uptake and excretion. Common bile duct and hepatic ducts well-visualized. Gallbladder fills within 30-45 minutes and appears as focal activity in the right upper quadrant. Tracer enters small bowel within 60 minutes. Normal biliary-enteric continuity. No obstruction.
Acute Cholecystitis
Normal hepatic uptake with prompt biliary duct visualization. Common bile duct and hepatic ducts fill appropriately. Small bowel activity present. Gallbladder NOT visualized at 60 minutes or after morphine administration. Findings confirm cystic duct obstruction and acute cholecystitis.
Clinical Applications
Diagnostic Confirmation
When ultrasound is equivocal:
- Ultrasound may show gallstones without signs of inflammation
- HIDA confirms functional obstruction
- High negative predictive value: normal scan effectively excludes acute cholecystitis
High-risk patients:
- Critically ill patients with acalculous cholecystitis
- Confused or non-communicative patients
- Atypical presentations
Surgical Planning
Urgency assessment:
- Positive scan (non-visualized gallbladder): Urgent cholecystectomy
- Rim sign: Emergency surgery (gangrene concern)
- Delayed visualization: May allow semi-elective surgery
Laparoscopic planning:
- Confirms diagnosis preoperatively
- Reduces negative laparoscopies
- Guides discussion of surgical risks
Biliary Dyskinesia
Functional gallbladder disorder:
- CCK (cholecystokinin) stimulation added to HIDA scan
- Measures gallbladder ejection fraction
- ＜40% ejection fraction suggests biliary dyskinesia
- Patients may benefit from cholecystectomy
What Else Could It Be?
Non-visualized gallbladder with normal hepatic uptake and bile duct visualization. Positive Murphy's sign. Right upper quadrant pain ＞6 hours. Fever and leukocytosis often present.
Normal gallbladder visualization on HIDA scan. Pain typically ＜6 hours, resolving spontaneously. No fever or significant leukocytosis. Gallstones present but cystic duct patent.
Same HIDA pattern as calculous cholecystitis but no gallstones. Typically in critically ill patients, trauma, or prolonged fasting. Higher complication rate.
Poor hepatic uptake of tracer on HIDA. Elevated transaminases (AST/ALT) disproportionately elevated compared to alkaline phosphatase. May have jaundice.
Evidence-Based Outcomes
Preparing for Your Scan
- Fasting: Nothing to eat or drink for 4-6 hours before the test
- NPO status: Critical because recent eating causes false positive (gallbladder fills even if cystic duct obstructed)
- Medications: Provide list of current medications
- Pain medications: May be given but inform imaging staff
Understanding Your Results
What Happens Next?
Surgical Consultation
Emergency surgery consult for urgent laparoscopic cholecystectomy. Discuss timing, risks, and benefits of surgery.
Preoperative Preparation
IV fluids, antibiotics, pain control. Preoperative labs including CBC, liver function tests, and coagulation studies.
Cholecystectomy
Laparoscopic gallbladder removal. Conversion to open surgery may be needed if difficult anatomy or complications present. Intraoperative cholangiogram may be performed.
Postoperative Recovery
Most patients go home same day or next day. Return to normal activities within 1-2 weeks. Watch for complications like bile duct injury or retained stones.
Frequently Asked Questions
Is acute cholecystitis a surgical emergency?
Acute cholecystitis requires urgent but not emergency surgery in most cases. Cholecystectomy within 24-48 hours of diagnosis is recommended to prevent complications like gangrene or perforation. Emergency surgery (immediately) is needed if gangrene, perforation, or sepsis develops.
What happens if acute cholecystitis is not treated?
Untreated acute cholecystitis can progress to gallbladder gangrene, perforation, bile peritonitis, abscess formation, and sepsis. These complications are life-threatening and require emergency surgery. Prompt diagnosis and treatment prevents progression.
Can HIDA scan miss acute cholecystitis?
HIDA scan is extremely sensitive (＞95%) for acute calculous cholecystitis when performed properly with morphine augmentation. False negatives can occur with recent eating (false positive gallbladder visualization), severe hepatocellular disease, or anatomic variants.
Will I need open surgery or laparoscopic surgery?
Most cholecystectomies are performed laparoscopically through small incisions. Open surgery (larger incision) may be needed for difficult anatomy, severe inflammation, or complications. Conversion to open surgery occurs in 5-10% of laparoscopic cases.
References
- American College of Radiology. ACR Appropriateness Criteria: Right Upper Quadrant Pain. 2024.
- Society of Nuclear Medicine and Molecular Imaging. SNMMI Procedure Guidelines for Hepatobiliary Scintigraphy. 2023.
- The Society of American Gastrointestinal and Endoscopic Surgeons. Guidelines for the Clinical Application of Laparoscopic Biliary Tract Surgery. 2024.
Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.
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