Diagnosis of Aneuploidies by amniocentesis in high risk cases of first trimester screening test

Document Type : Original Article


1 M.Sc. of Midwifery, School of Paramedics, Islamic Azad University, Bonab Branch, Bonab, Iran.

2 M.Sc. of Midwifery, Faculty of Medicine, Islamic Azad University, Tabriz Branch, Tabriz, Iran.

3 M.Sc. of Library and Information Science, School of Nursing and Midwifery, Tabriz University of Medical Sciences, Tabriz, Iran.


Introduction: Early diagnosis of congenital abnormalities at early of pregnancy and termination of these pregnancies can prevent from birth of defective newborns that are overload for family and society. This study was performed with the aim to diagnose aneuploidies by amniocentesis in high risk cases identified by first trimester screening test.
Methods: This descriptive-analytic (cross-sectional) study was performed on 121 pregnant women that their result of Down syndrome and other Aneuploidy screening were high risk at first trimester of pregnancy (11 to 13 weeks and 6 days) and were referred to fetus medicine section of Tabriz Alzahra hospital to perform amniocentesis (15-20 weeks) in 2013. A questionnaire was used for data collection which includes demographic characteristics of the subjects, data obtained by the results of first trimester screening tests, and data obtained by amniocentesis (the results of fetus karyotype). Data was analyzed using SPSS software (version 13) and coefficient tests, T-Test, and ANOVA. P≤0.05 was considered significant.
Results: Aneuploidy was detected in 11 newborns that 5 Down syndrome, 3 cases of trisomy 18, and 1 Klinefelter's syndrome were identified. There were significant relationship between risk of Down syndrome and amniocentesis results (P= 0.0001) and between increasing NT thickness and amniocentesis results (P= 0.04). There was no significant relationship between demographic characteristics of the subjects and results of first trimester screening (P>0.05). There were significant relationship between age (P= 0.03), number of delivery (P= 0.047), number of alive children (P= 0.036) and history of anomaly in previous child (P= 0.001) and amniocentesis results.
Conclusion: In the present study, 10% of high risk cases identified by first trimester screening test were diagnosed as aneuploidy by amniocentesis.


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