Diagnostic Ultrasound - Abdomen and Pelvis

Choledochal Cyst
Diagnoses: Biliary System
TERMINOLOGY
• Spectrum of extrahepatic and intrahepatic bile ducts
malformations characterized by fusiform dilatation
IMAGING
• Todani Classification
○ Type I: Solitary fusiform or cystic dilatation of common
duct
○ Type II: Extrahepatic supraduodenal diverticulum
○ Type III: Choledochocele
○ Type IVa: Both intrahepatic and extrahepatic cysts
○ Type IVb: Multiple extrahepatic cysts without
intrahepatic cysts
○ Type V: Single or multiple intrahepatic cysts (Caroli
disease)
• Ultrasound
○ Cystic extrahepatic mass separated from gallbladder and
communicating with common hepatic or intrahepatic
ducts
KEY FACTS
○ Intrahepatic ductal dilatation due to simultaneous
involvement or secondary to stenosis
• MRCP and ERCP: Best depiction of choledochal cysts and
anomalous pancreatobiliary junction union
TOP DIFFERENTIAL DIAGNOSES
• Biliary obstruction of various causes
• Pancreatic pseudocyst
• Primary sclerosing cholangitis
• Recurrent pyogenic cholangitis
CLINICAL ISSUES
• Usually diagnosed in childhood (80%)
• Triad: Recurrent RUQ pain, jaundice, palpable mass
• Complications: Biliary calculi, cholangitis, carcinoma
• Surgical excision and enterobiliary reconstruction
DIAGNOSTIC CHECKLIST
• Rule out other conditions that can cause marked biliary
dilatation
Graphic shows Todani classification of choledochal cyst. Type I: Solitary extrahepatic involvement; II: Diverticulum; III: Choledochocele;
IVa: Multiple extrahepatic and intrahepatic involvement, IVb: Multiple extrahepatic involvement without intrahepatic involvement; V:
Caroli disease.
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