The Value of Exome Sequencing in Thoracoamniotic Shunt for Severe Pleural Effusion with Fetal Hydrops: A Retrospective Clinical Study.

Objective: We aimed to study the value of exome sequencing (ES) in severe pleural effusion with nonimmune hydrops fetalis (NIHF) that underwent thoracoamniotic shunt (TAS).

Methods: It was a retrospective study of NIHF that underwent TAS between 2012 and 2020 at Shanghai First Maternity and Infant Hospital. After a detailed assessment, NIHF cases with aneuploidies, infections, and structural anomalies were excluded, and TAS was offered to cases with severe pleural effusion. Quantitative fluorescence polymerase chain reaction (QF-PCR) was conducted to exclude Trisomy 21, 18, and 13 before fetal therapy, and chromosomal microarray analysis (CMA) was offered to all the cases. Before 2019, ES was retrospectively performed using stored fetal DNA extracted from prenatal samples; from 2019 onward, ES was discussed and offered before intrauterine therapies.

Results: A total of 18 NIHF cases underwent TAS with negative CMA and continuing pregnancy were included. Fetal hydrops was relieved in 16 cases (88.9%). The median gestational ages at intervention and at delivery were 31.2 (22.0-33.1) weeks and 34.3 (29.7-38.6) weeks, respectively. The neonatal survival rate was 72.2% (13/18), and no causative gene variants were identified from ES in any survivors. Pathogenic or likely pathogenic variants were detected in 3 out of 5 neonatal deaths. If rapid ES could have been available to guide fetal therapy, the neonatal survival rate after TAS would have increased from 72.2% to 86.7%.

Conclusions: Single-gene disorders were one of the major causes of perinatal death in NIHF cases that underwent fetal therapy. Prenatal rapid ES may be of good promise in NIHF to explore precise etiology and guide fetal therapy.