Efficiency of Prenatal Down Syndrome Diagnosis in the six oblasts of the south-east and central regions of Ukraine
Authors:   Interregional Center of Medical Genetics and Prenatal Diagnosis, Krivoy Rog, Ukraine, Veropotvelyan N.P. 
Published: March 2021

Chromosomal aneuploidy (CA), having an incidence rate of 6-8 per 1000 live births, holds a special place in the structure of congenital and hereditary pathology. Among the common CA, trisomy 21 chromosomes (T21) is the most frequently found (its incidence rate in the general population amounts to 1:700–800 live births). The objective: to study the efficiency of prenatal screening of CA (Down’s syndrome, DS) in the areas under the Center’s operational activity in the period of 2010-2015; To estimate the actual prevalence of DS in terms of born and prenatally diagnosed, eliminated fetuses with T21; On the basis of retrospective analysis of indications for prenatal karyotyping, in all detected cases of DS, to specify their structure and incidence rate; Based on data from medical literature, to make a comparative analysis with similar studies in different countries around the world. Patients and methods. Over the six years (2010–2015) we have performed 3,137 invasive prenatal interventions, among which are 720 chorionic villus biopsies, 929 placententesises, and 1,488 amniocentesis of pregnant women having a high risk of CA, who were seeking medical help from our center whose operational activity covers 6 provinces (oblasts). Results. From 3,137 prenatally karyotyped studies, there have been found only 558 cases of fetal CA, including 288 fetuses with T21. A retrospective analysis of the structure of indications for invasive prenatal diagnosis in 288 pregnant women, having fetuses with prenatally detected DS, is presented as follows: – separate: only 40-aged and above mothers – 4 (1.38%); Ultrasound (US)-findings (anomalies and markers of CA) – 192 (69.5%); High biochemical risk of CA – 2 (0.7%). – combined: the mother’s age is 40 and above + US findings – 36 (13%); The mother’s age is 40 and above + US and biochemical (BC) markers – 8 (2.8%); Ultrasound findings + positive BC test – 32 (11.5%). Delivery of the previous child with DS by a pregnant woman under 40 years with no ultrasound and BC markers – 1 (0.34%). In total, ultrasound findings (anomalies and markers of CA) were found in 97.5% of cases of prenatally detected fetuses with DS. The index of prenatal detection of fetuses with Down syndrome of all registered karyotyped cases of T21 (pre- and postnatal) in the Dnepropetrovskaya oblast corresponds to the average European level - 65%, (in the areas of the center’s operational activity – 37.7%). Taking into account 242 cases of DS in fetuses aborted prior 22 weeks of gestation, the actual prevalence of T21 in case of their birth would be 1:766 (13 per 10.000 infants). Conclusions. Prevalence of Down syndrome among newborns in the Dnepropetrovskaya oblast as a result of prenatal diagnosis of chromosomal abnormalities makes 1: 1257, which is 1.8 times lower than the incidence in the average population (1:700); In other areas covered by the center’s consulting and diagnostic activity this rate is 1.1–1.55 times lower than that of the population one. In the absence of the existing system of prenatal diagnosis of Down syndrome, its average prevalence in these provinces would correspond to that of the general population 1:766 newborns. Key words: сhromosomal abnormalities, Down syndrome, prenatal screening strategies, ultrasound diagnosis, invasive prenatal diagnosis, ultrasound markers.