الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Prenatal cytogenetic testing is an option for pregnancies at increased risk of chromosomal abnormalities based on maternal age, abnormal maternal serum screening results, history of sibling chromosomal abnormalities or fetal anomalies observed by ultrasound. Moreover, the risk-to-benefit ratio of offering invasive prenatal testing to all pregnancies regardless of risk factors is an active area of discussion in the obstetrics and genetics communities.Conventional forms of cytogenetic analysis such as G-banded chromosome analysis and FISH (fluorescence in situ hybridization) techniques are currently the mainstay of prenatal diagnosis of chromosomal abnormalities. However, there are many technical problems in karyotyping of amniotic cells, so the current guidelines and standards for prenatal diagnosis of chromosomal defects predate the technical feasibility for detection of an increasing number of chromosomal deletion and duplication syndromes spread throughout the genome by methods such as array-based comparative genomic hybridization. Prenatal screening and cytogenetic diagnostic methods were done for 30 pregnant women at high risk for fetal chromosomal abnormalities during the period between March 2019 to Feb 2021 to determine the frequency of chromosomal abnormalities in high risk pregnancies among Egyptian women and to establish amniotic cell culture technique in MUCH Genetic Unit for further work up.Screening with nuchal translucency, maternal serum biochemical makers and ultrasound done for all cases. Amniocenteses done for all 30 cases and karyotyping for succeeded cultured amniotic cells was done but cells were in interphase . FISH was done for last 10 cases with rapid accurate results.The sixteen completed pregnancies were followed postnatally for general examination and karyotyping ,14 babies were born with abnormalities and two were normal. Among these 14 babies ,one was diagnosed prenatally with FISH as trisomy 21 and confirmed postnatally with karyotyping ,and two cases were diagnosed postnatally by clinical examination and karyotyping as trisomy 21while the remaining were with non aneuploidy congenital anomalies. Amniotic cell culture growth significantly related to gestational age as with advance of pregnancy the chance of culture failure increase ,while there was no significant relation between culture failure and fetal chromosomal abnormality. There was significant relation between abnormal NT and sonographic findings regarding fetal structural defects and also there was strong positive correlation between NT and gestational age and so ACOG defines an abnormal nuchal fold as≥6mm in 2nd trimester and 2nd trimester thickened nuchal fold has high specificity for aneuploidy. CHD was the most frequent fetal structural anomalies in our cases representing 26.7% of cases.