ABSTRACT

In this study, we aimed to evaluate the demographic data and cytogenetic results of prenatal diagnoses performed in a single genetics laboratory setting over a period of 21 years.

This study is a retrospective analysis of patients who underwent prenatal diagnosis in our center between 2000 and 2021. A total of 2,385 cases between the ages of 18-48 were included in the study. Age, indication, pregnancy week, type of prenatal diagnosis, and the result of cytogenetic analysis of the cases were evaluated.

The mean age of the patients was 33.97 ± 4.96 years and 1,205 (50.5%) patients were under 35 years. Amniocentesis was performed in 1,965 (82.4%) patients, chorionic villus sampling in 279 (11.7%) patients, and cordocentesis in 141 (5.9%) patients. A total of 2,114 (88.6%) were normal and 253 (10.6%) were found to have abnormal karyotypes. The most frequently observed abnormal karyotypes were trisomy 21, translocation, and inversion of chromosome 9 (3.6%, 1.4% and 1.0% respectively. The most common indications were: abnormal ultrasonography results in 695 (29.1%), abnormal first trimester test results in 513 (21.5%), and advanced maternal age in 399 (16.7%) patients. The highest positive predictive value for prenatal diagnosis (or abnormal result) was 73.9% for Non-invasive Prenatal Test (NIPT), followed by in paternal chromosome anomaly (17.4%), and an abnormal USG evaluation (14.5%).Results: The mean age of the patients was 33.97 ± 4.96 years and 1,205 (50.5%) patients were under 35 years. Amniocentesis was performed in 1,965 (82.4%) patients, chorionic villus sampling in 279 (11.7%) patients, and cordocentesis in 141 (5.9%) patients. A total of 2,114 (88.6%) were normal and 253 (10.6%) were found to have abnormal karyotypes. The most frequently observed abnormal karyotypes were trisomy 21, translocation, and inversion of chromosome 9 (3.6%, 1.4% and 1.0% respectively. The most common indications were: abnormal ultrasonography results in 695 (29.1%), abnormal first trimester test results in 513 (21.5%), and advanced maternal age in 399 (16.7%) patients. The highest positive predictive value for prenatal diagnosis (or abnormal result) was 73.9% for Non-invasive Prenatal Test (NIPT), followed by in paternal chromosome anomaly (17.4%), and an abnormal USG evaluation (14.5%).

It is necessary to carry out more studies on NIPT, which has a high positive predictive value, and develop the results for genetic counselling together with conventional and molecular cytogenetic methods.