Fetal ultrasound findings in trisomy 18 at midpregnancy

Abstract

Trisomy 18 (Edwards' syndrome), a lethal chromosomal aberration, is the second most common autosomal trisomy with an incidence 1: 8000. The aim of this study is to evaluate the sonographic findings in fetuses with trisomy 18. In ten years period (2002-2012) we analyzed fetal blood samples for chromosome abnormalities. Samples were taken by cordocentesis and processed using standard techniques. Sixteen metaphase cells were analyzed for chromosomal constitution in each sample after tripsin-Giemsa banding. A retrospective review of the cytogenetic laboratory database identified all cases of trisomy 18 in ten years period. The prenatal sonographic studies in fetuses at 16 to 22 weeks' gestation, done before invasive testing for the karyotype were reviewed for anatomic findings. From 2100 samples of fetal blood analyzed for chromosomal abnormalities, there were 16 (0,8%) with complete trisomy 18. We found no mosaicism, or partial trisomy 18. The women that carried fetuses with trisomy 18 were 17 to 42 years of age. Four of them were above 35. From 16 fetuses with trisomy 18, 14 (87,5%) had some anomaly detected by ultrasound, and other two were tested because of advanced maternal age. The most common findings in trisomy 18 were intrauterine growth retardation, polyhidramnios and anomalies of central nervous system, in 29% respectively. Multiple anomalies, including central nervous system, hart and gastrointestinal system anomalies, were also frequent (21%). Therapeutic termination of pregnancy was done in all cases after genetic counseling. Screening for chromosomal abnormalities using ultrasound is at utmost importance in cases of nonhereditary aberrations. Detailed ultrasonographic examinations of fetuses will enable health care providers to form the appropriate management plan for each patient.