Cystic anomalies of biliary tree in the fetus: is it possible to make a more specific prenatal diagnosis?

Background/purpose: Biliary tree cystic malformations (BCM) occur rarely. Current progress in ultrasonography makes it possible to identify them prenatally. The aim of this study was to analyze retrospectively prenatal ultrasound patterns of 5 consecutive subhepatic cysts in an effort to differentiate the BCM before birth and onset of symptoms.

Methods: The prenatal ultrasound patterns of 5 consecutive BCM were correlated with the postnatal diagnosis.

Results: Case 1 showed a hyperechogenic cyst that underwent enlargement during fetal life; the diagnosis at birth was an obstructed choledochal cyst (CC). In cases 2 and 3, an anechoic cyst with small, stable dimensions during pregnancy was identified; a biliary atresia (BA) type III-C was confirmed at birth. A slightly hyperechogenic cyst with no increase in size at repeated prenatal scans, was observed in cases 4 and 5; a CC and a cystic lesion at the confluence of the hepatic ducts (without obstruction) were diagnosed postnatally, respectively.

Conclusions: The ultrasound scan pattern and size allow to make a prenatal differential diagnosis of BCM. Anechoic, small cyst in the hepatic hilum is highly suspicious for BA. Large, echoic or enlarging cyst is strongly suggestive of "obstructed" CC. Echoic, small and stable cyst is more suggestive of "unobstructed" CC.