Failure of NIPT to detect constitutional chromoanasynthesis involving chromosome 21 in a case of fetal hydrops-A case report.

We report a case of a de novo ring 21 complex chromosomal rearrangement in a fetus presenting with hydrops. Noninvasive prenatal testing (NIPT) failed to detect the imbalance. This case highlights the need to understand the various limitations and strengths of NIPT technology when counseling patients.