- 1 in 1,000 fetuses at 20 weeks’ gestation.
- Small or absent gallbladder.
- In most cases this is a transient finding (75%), but some are due to isolated gallbladder agenesis (15%), cystic fibrosis (10%) and rarely biliary atresia (3%).
- In about 25% of cases of biliary atresia there associated heterotaxy syndrome, which includes situs inversus, polysplenia, malrotation of the gut intestinal atresia and heart defects.
- Detailed ultrasound examination.
- Amniocentesis: DNA studies for cystic fibrosis if both parents are carriers.
- Limited data suggest that in biliary atresia there are very low levels of digestive enzymes in amniotic fluid at <24 weeks’ gestation.
- Follow-up should be standard.
- Standard obstetric care and delivery.
- Biliary atresia is a serious condition requiring liver transplantation.
- Gallbladder agenesis is a benign condition.
- No increased risk of recurrence.