Isolated Nonvisualization of the Fetal Gallbladder Should Be Considered for the Prenatal Diagnosis of Cystic Fibrosis.

BACKGROUND: Cystic fibrosis (CF) can be revealed during fetal life by diverse ultrasound digestive abnormalities (USDA) such as fetal echogenic bowel or fetal intestinal loop dilatation, nonvisualization of the fetal gallbladder (NVFGB) being rarely observed in isolation. Only 6 cases of CF revealed by isolated NVFGB have been reported so far in the literature. Furthermore, recent studies suggested that this sign is of poor predictive value for CF. METHODS: We report on the results of a 6-year French tricenter study on 1,124 cases of fetal USDA for whom a comprehensive molecular study was performed for CF. RESULTS: Among the 37 CF fetuses, 5 (13.5%) presented with isolated NVFGB at ultrasound (US) examination at 24-31 weeks of gestation. This sign was more frequently observed in CF fetuses than in non-CF fetuses, with a likelihood ratio of 2.7. The genotypes included three c.1521_1523del (F508del) homozygous cases and two compound heterozygous cases for a frequent and a rare CF-causing variant. DISCUSSION: These observations highlight the importance to report on the presence and aspect of the fetal gallbladder at the second trimester US scan and to consider prenatal CFTR molecular analysis in cases of isolated NVFGB.