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.