We report about 4 cases of prenatal diagnostics of mosaic trisomy 9 in the first trimester of pregnancy.
The data of ultrasound, cytogenetic and pathoanatomical studies are presented. Prenatal diagnosis of trisomy
9 is difficult due to the non-specificity of the anomalies characteristic of it. Trisomy 9 in complete or mosaic
form in chorionic villus cells may not be confirmed in the fetal tissues. Interpreting the results of cytogenetic
analysis of chorionic villus cells and deciding on the prognosis of pregnancy with trisomy 9, the whole complex of clinical data should be taken into account: the results of the ultrasound examination and additional
cytogenetic studies, anamnesis