Cytogenetic analysis in fetuses with late onset abnormal sonographic findings.

Objective: To determine the rate of chromosomal cytogenetic abnormalities in fetuses with late onset abnormal sonographic findings.
Design: Retrospective cohort of women who underwent amniocentesis at or beyond 23 weeks of gestation, for fetal karyotype and chromosomal microarray analysis, indicated due to late onset abnormal sonographic findings.
Results: All 103 fetuses had a normal karyotype. Ninety-five women also had chromosomal microarray analysis (CMA) performed. The detection rate of abnormal CMA (5/95, 5.3%) was similar to that of women who underwent amniocentesis due to abnormal early onset ultrasound findings detected at routine prenatal screening tests during the first or early second trimester (7.3%, P=0.46) and significantly higher than that for women who underwent amniocentesis and CMA upon request, without a medical indication for CMA (0.99%, P<0.0001).
Conclusions: Late onset sonographic findings are an indication for amniocentesis, and if performed, CMA should be applied to evaluate fetuses with late onset abnormal sonographic findings.