Distinguishing Choledochal cyst from Cystic biliary atresia

Most critical prenatal hepatobiliary differentials

Condition	Nature	Prognosis
Choledochal cyst	Bile duct dilatation	Excellent after surgery
Cystic biliary atresia	Progressive duct obliteration	Time-sensitive liver disease

Key difference:

• Choledochal cyst → dilated duct
• Biliary atresia → obstructed duct

Embryologic and Pathologic Difference

Choledochal Cyst (Developmental dilation)

Mechanism:

• Abnormal pancreaticobiliary junction
• Enzyme reflux
• Progressive bile duct dilation

Structure:

• Patent bile ducts
• Cyst communicates with biliary tree

Cystic Biliary Atresia (Obstructive destruction)

Mechanism:

• Inflammatory or developmental obliteration of ducts

Structure:

• Obliterated bile ducts
• Small cyst at porta hepatis
• Progressive liver fibrosis

1. Gallbladder — The Single Most Useful Marker

Feature	Choledochal Cyst	Cystic Biliary Atresia
Gallbladder	Usually present	Often absent or very small
Shape	Normal	Irregular or atretic
Contractility	Present	Absent

Absent gallbladder strongly favors biliary atresia.

2. Cyst Size

Feature	Choledochal Cyst	Cystic Biliary Atresia
Size	Usually >10–15 mm	Usually <10–20 mm
Growth	Progressive enlargement	Often stable or small

3. Cyst Location

Both occur near porta hepatis, but subtle differences exist.

Choledochal cyst:

• Near common bile duct
• Often below liver hilum

Cystic biliary atresia:

• At porta hepatis
• Closer to liver hilum

3. Intrahepatic Bile Ducts

Feature	Choledochal Cyst	Cystic Biliary Atresia
Intrahepatic ducts	May be dilated	Usually absent

Choledochal Cyst

After birth:

• Jaundice may occur later
• Surgery elective but necessary

Typical treatment:

• Cyst excision
• Hepaticojejunostomy

Outcome: Excellent

Cystic Biliary Atresia

After birth:

• Early cholestatic jaundice
• Rapid liver damage

Treatment: Kasai portoenterostomy

Timing critical: Before 60 days

Outcome depends on:

• Early surgery
• Liver damage

Some require:

• Liver transplant

Feature	Choledochal Cyst	Cystic Biliary Atresia
Gallbladder	Present	Absent
Cyst size	Large	Small
Liver	Normal	Progressive fibrosis
Intrahepatic ducts	Dilated	Absent
Prognosis	Excellent	Time-dependent
Surgery	Planned	Urgent

Gallbladder visualization is the single most powerful prenatal discriminator.