Objectives: To prospectively evaluate the objective differential characteristics between cystic biliary atresia and choledochal cysts on sonography among neonates and young infants.
Methods: Twenty-three patients who had sonographic findings of a portal cyst and a final diagnosis were included. Their final diagnoses were cystic biliary atresia in 12 patients and choledochal cysts in 11. All of them underwent detailed sonographic scanning. Data for cystic biliary atresia and choledochal cyst groups were compared by the χ(2) test for categorical variables and an unpaired t test for continuous variables.
Results: The triangular cord sign was detected in 11 patients in the atresia group but in none in the cyst group (P < .001). Nine of 11 patients in the cyst group had dilatation of intrahepatic bile ducts, whereas none in the atresia group had that feature (P < .001). Sonography also showed sludge deposits in the cysts in 6 of 11 patients in the cyst group, whereas none in the atresia group had sludge deposits (P = .005). The mean width and length of the cysts in the cyst group were significantly larger than those in the atresia group (P< .05 for both). The mean hepatic artery diameter was significantly larger in the atresia group than in the cyst group (P < .001). The difference in gallbladder abnormalities between the atresia (n = 11) and cyst (n = 0) groups was also significant (P < .001). When all specific sonographic features were used, all patients were correctly classified into the atresia and cyst groups.
Conclusions: The triangular cord sign, intrahepatic bile duct dilatation, and echoic cysts might be regarded as objective sonographic features for differentiating cystic biliary atresia and choledochal cysts. Other sonographic features might be very supportive.