The importance of prenatal screening and prenatal diagnosis in the identification of numerical chromosomal abnormalities

Objectives and aim: The obstetric care of a pregnancy, as it is practiced today, includes non-invasive screening approaches as well as invasive procedures for a definitive prenatal diagnosis of fetal disorders, correlations between indicators for prenatal cytogenetic diagnosis, and results of chromosomal analysis made upon fetal cells. The aim is to introduce the prenatal invasive and non-invasive diagnostic methods during the first and second trimesters of pregnancy, thus providing early detection and prevention of chromosomal abnormalities and congenital developmental disorders within pregnancy outcomes in Mongolia. Results: The indications to perform prenatal cytogenetic diagnosis for numerical chromosomal abnormalities were abnormal biomarkers of double and triple testing, advanced maternal age, fetal abnormality detected through ultrasound, and positive obstetric history for chromosomal aneuploidy. The study identified 3 cases with abnormal numeric chromosomes of the two Downs cases showed karyotypes 47, XX, 21+, cytogenetic types of Down Syndrome (DS) and one case was karyotypes 47, XY, 13+, cytogenetic types of Patau Syndrome. Conclusions: Our study is unique in that it is the first such scientific examination of mothers at risk for congenital abnormalities in Mongolia. This study provides empirical evidence that the combination of an effective prenatal screening and cytogenetic diagnosis for fetal aneuploidycan be applied to pregnancy outcomes in Mongolia.