Detection and Clinical Significance of Chromosomal Mosaicism in Prenatal Diagnosis: A Retrospective Study From a Prenatal Diagnosis Center.

BACKGROUND

To evaluate the detection capabilities of prenatal screening and diagnostic methods for fetal chromosomal mosaicism and analyze associated pregnancy outcomes.

METHODS

This retrospective study included 79 cases of fetal chromosomal mosaicism identified by karyotyping among 8106 women undergoing prenatal diagnosis. Sensitivity of screening methods (first-trimester serum screening, second-trimester serum screening, and noninvasive prenatal testing (NIPT)) and concordance of diagnostic methods (chromosomal microarray analysis (CMA), multiple STR locus analysis technique (QF-PCR)) with karyotyping were assessed. Pregnancy outcomes were analyzed.

RESULTS

NIPT demonstrated significantly higher sensitivity (90.74%) compared with first-trimester serum screening (57.41%) and second-trimester serum screening (39.29%) (p < 0.001). CMA showed high concordance with karyotyping (90.00%), whereas QF-PCR exhibited significantly lower concordance (58.21%) (p < 0.001). The pregnancy termination rate was 57.14% (40/70). All trisomy 21 and trisomy 13 mosaicism cases resulted in termination, while decisions regarding other autosomal and sex chromosome mosaicism were more variable.

CONCLUSION

NIPT outperforms traditional serum screening for detecting chromosomal mosaicism, though karyotyping remains essential for confirmation. CMA aligns well with karyotyping, particularly for low-level mosaicism. The high termination rate underscores the critical need for multidisciplinary genetic counseling integrating genetic, imaging, and clinical data.