Postnatal Outcome After Ultrasound Findings of an Abnormal Fetal Gallbladder: A Systematic Review and Meta-Analysis.

Objective: To describe postnatal outcome following the prenatal diagnosis of an abnormal fetal gallbladder.

Methods: We conducted a systematic review of studies from January 1980 to January 2023 that described FGB abnormalities, which included agenesis or non-visualisation, abnormal content presence of sludge, abnormal shape or size and abnormal position, and postnatal outcome to determine the association with pathology.

Results: In 51 studies, 842 fetuses had abnormal FGB. Non-visualisation of the FGB was the most common diagnosis (521 fetuses, mean gestational age 21.6 weeks, range 14-29). The FGB was subsequently visualised prenatally in 128 out of 521 cases (24.6%; 95% CI, 20.9%-28.3%). Of the 393 cases with persistent FGB non-visualisation (75.4%; 95% CI, 71.7-79.1), 48 cases (12.2%; 95% CI, 9.0-15.5) underwent termination of pregnancy (TOP) with FGB agenesis confirmed in 16 out of 26 fetuses that had a postmortem examination (61.5%; 95% CI, 42.8-80.2). After excluding cases with missing outcomes (n = 121), postnatal ultrasound was performed in 82.4% of cases with persistent non-visualised FGB (224/272; 95% CI, 77.8%-86.9%). The gallbladder was not visualised in 63.4% (142/224; 95% CI, 57.1-69.7), confirming GB agenesis. This was an isolated finding in 41.1% of cases (92/224; 95% CI, 34.6-47.5). Of 272 known outcomes, biliary atresia, cystic fibrosis, and structural or chromosomal abnormalities were diagnosed in 8.5% (n = 23), 12.5% (n = 34), 18.0% (n = 49) and 6.3% (n = 17) cases, respectively. The sensitivity (true positive rate) of ultrasound for GB agenesis in fetuses with persistently non-visualised FGB was 58.1% (158/272; 95% CI, 52.2%-64.0%). Fetal gallbladder stones/sludge were described in 100 fetuses mainly in the third trimester of pregnancy (mean gestational age 33.8 weeks). Resolution of postnatally followed up cases occurred in around one-third of the cases (37.3%) within 1 month after birth. There was a low reported association with severe conditions (2%).

Conclusions: This systematic review and meta-analysis found that when the fetal gallbladder was absent in mid-trimester, it was visualised in subsequent fetal ultrasound examinations in around 25% of cases. If persistently absent on prenatal ultrasound, the confirmed rate of GB agenesis was around 50%, with the neonates having biliary atresia, cystic fibrosis, or structural abnormalities. Because of the association with severe conditions, if persistent FGB agenesis is suspected, prenatal diagnosis should be offered. FGB abnormalities such as stones/sludge tended to resolve by 1 year of age with around half of all cases resolving by 1 month postnatal.