Early differential diagnosis of cystic biliary atresia and choledochal cyst in the fetus: A multicenter retrospective study.

Background/purpose: Fetal hilar cyst is primarily diagnosed as two diseases after birth, cystic biliary atresia (CBA) and choledochal cyst (CC). The aim of our study was to explore more reliable indicators in early differential diagnosis of these cysts.

Methods: We recruited a total of 50 cases with a prenatal diagnosis of hepatic cyst at three centers, and patients were divided into a CBA group (n = 16) and CC group (n = 34) according to postnatal intraoperative diagnosis. Patient features, maximal cyst diameter as measured by prenatal and early postnatal ultrasonography were analyzed and compared between the two groups, as was the effect of cyst size in predicting CBA.

Results: The maximal cyst diameters in the last prenatal ultrasound (LPU) measurement and initial postnatal ultrasound (IPU) in the CBA group were significantly smaller than in the CC group, as was the difference between the IPU and the first prenatal ultrasound (FPU) (i.e., IPU-FPU) in the CBA group relative to the CC group. The IPU-FPU difference showed the best diagnostic performance as a single parameter (AUC, 0.9806), with a sensitivity and specificity of 100% and 90.3%, respectively, and a cutoff value of 7.5 mm.

Conclusion: Ultrasonographic measurement of the maximal cyst diameter can assist in early (within 1 week after birth) identification of CBA. An IPU-FPU <7.5 mm suggested a higher possibility of a postnatal diagnosis of CBA.