Utility of chromosomal microarray for diagnosis in cases of nonimmune hydrops fetalis.

PURPOSE: Chromosomal microarray (CMA) is recommended in the diagnostic evaluation of cases with fetal structural anomalies when invasive testing is pursued. However, the utility of CMA for nonimmune hydrops fetalis (NIHF) specifically is not well known. Our objective was to describe the overall yield of CMA in the diagnostic evaluation of NIHF, comparing isolated cases to those with concurrent structural anomalies.

METHODS

This was a retrospective cohort study of all prenatally diagnosed NIHF cases evaluated at the University of California, San Francisco from 2008 to 2018. NIHF due to twin-twin transfusion syndrome was excluded.

RESULTS

There were 131 cases of prenatally diagnosed NIHF. In 43/44 cases with a CMA performed, results were categorized as normal or likely benign. One case was found on CMA to have a large pathogenic duplication of 21p11.2q22.3, which could have been detected by karyotype and was consistent with a diagnosis of Down syndrome. There was no incremental yield demonstrated for CMA over karyotype.

CONCLUSIONS

Among a cohort of prenatally diagnosed NIHF cases, CMA did not identify any copy number variants beyond those detectable by karyotype, and the vast majority of CMAs were normal. These results suggest that CMA has low diagnostic utility for NIHF.