What is the purpose of a cholangiogram?

Purpose of Cholangiography

Cholangiography serves to visualize the biliary tree anatomy, detect common bile duct stones, identify strictures or tumors, assess biliary patency, and prevent or diagnose bile duct injuries during surgical procedures. 1, 2

Diagnostic Applications

Anatomical Visualization

• Cholangiography provides detailed imaging of the extrahepatic and intrahepatic biliary tree, allowing identification of anatomical variants that may alter surgical approach 2, 3
• The procedure demonstrates the cystic duct junction, common bile duct, and intrahepatic ductal anatomy with high precision 2, 4
• In primary sclerosing cholangitis (PSC), cholangiography is essential for diagnosis, revealing characteristic multifocal strictures with a "beaded" appearance, slight biliary dilatation, and diverticular outpouchings 1

Stone Detection

• Cholangiography identifies unsuspected common bile duct stones in 5.7% of cases where they were not clinically suspected 3
• The technique detects choledocholithiasis with 92% sensitivity and 99% specificity when performed via magnetic resonance cholangiography (MRC) 5
• Approximately 30% of common bile ducts suspected to contain stones are proven clear on cholangiography, avoiding unnecessary choledochotomy 3

Malignancy Evaluation

• Cholangiography is essential for early diagnosis of cholangiocarcinoma and assessing tumor resectability 1
• The procedure determines the extent of duct involvement by tumor and identifies the level of biliary obstruction 1
• When combined with brush cytology and biopsy during ERCP, diagnostic yield for cholangiocarcinoma reaches 40-70% 1

Therapeutic and Safety Applications

Intraoperative Use

• Operative cholangiography during cholecystectomy prevents iatrogenic bile duct injury by clearly delineating anatomy before critical dissection 2, 6, 4
• The procedure facilitates identification of the best approach for removing stones impacted in the distal common bile duct 3
• Intraoperative cholangiography confirms complete stone clearance after common bile duct exploration 3

Post-Procedural Assessment

• After percutaneous cholecystostomy, cholangiography performed 2-3 weeks post-placement demonstrates biliary tree patency and cystic duct status before catheter removal 1
• This assessment ensures absence of bile leak risk and reduces potential symptom recurrence 1
• A patent cystic duct on cholangiography increases the safety of drain removal by lowering leak risk 1

Modality Selection

Non-Invasive Cholangiography (MRCP)

• MRCP should be the initial cholangiographic modality for suspected biliary obstruction, offering 77-88% sensitivity without procedural risks 7
• MRCP accurately identifies both the level and cause of biliary obstruction in malignant and benign disease 5
• The technique is particularly valuable when ERCP cannot be performed or has failed 7

Invasive Cholangiography (ERCP/PTC)

• ERCP should be reserved for therapeutic interventions including stone extraction, stent placement for obstruction, and tissue sampling when malignancy is suspected 1, 7
• ERCP carries significant risks: 3-5% pancreatitis rate, 2% bleeding with sphincterotomy, 1% cholangitis, and 0.4% mortality 7
• Urgent ERCP is indicated for cholangitis or when immediate therapeutic decompression is required 7

Common Pitfalls

• Negative cytology from ERCP brushings does not exclude malignancy, as the positive yield is only 30% for cholangiocarcinoma 1
• Transcystic cholangiography during laparoscopic cholecystectomy achieves adequate visualization in only 68% of cases, compared to 92% with transgallbladder technique 6
• Cholecystocholangiography (direct gallbladder puncture) has a 52% failure rate and misses the cystic duct junction in 64.5% of cases, making it inferior to cystic duct cannulation 4
• MRCP sensitivity diminishes for stones smaller than 4mm 7