Implementing the Use of Ultrasonography Screening Markers of the Trisomy 18 in the Clinical Practice, in the Era of Non-invasive Prenatal Test: Case Reports

Abstract

Introduction: Edwards’s syndrome (Tr18) is a genetic disorder caused by trisomy of the chromosome 18, and its penetrance is cc. 1:5000. This Edwards-syndrome or trisomy18 associated with many different conditions and abnormalities, with the opportunity for the ultrasound screening. However, only invasive procedures can detect and diagnose this condition during intrauterine life. Aim: To report our experience with sonographic findings in pregnancies complicated by trisomy 18. Materials: This retrospective comparative study includes ten cases (N=10). Methods: All of the cases were observed between 2012 and 2017. Prenatal ultrasound screenings were performed following the Fetal Medicine Foundation criteria system. Biochemical screenings were performed in an accredited laboratory in Hungary (N=6). Data collected by using Astraia software. The genetic diagnosis was performed by the local medical genetic departments. Non-invasive genetic testing results (N=5) were compared to the genetic diagnostics. The maternal demographics data, prenatal sonographic findings, and chromosomal analysis results were obtained by reviewing the ultrasound reports and medical records. Results: The well-known markers of trisomy 18 has been performed as preliminary studies were observed. The most sensitive markers nuchal translucency thickness and hypoplastic nasal bone had proved their usefulness. Structural anomalies such as omphalocele, abnormal posturing of the hands, megacystis, heart defect, early-onset IUGR, single umbilical artery, and low fetal heart rate (bradycardia) were recorded. Detection rates of the tests/markers were 20-87.5%; while using three or more markers were the most effective. Discussion: There is a need for better understanding of the phenotype of Edwards's syndrome. The recognition of the specific first- and mid-trimester sonographic markers of trisomy 18 may improve detection of this serious condition cost-effectively. NIPT is slightly just another screening test, and without ultrasonography, it is not recommended to use in the clinical practice. Conclusion: These results once more confirm the need for genetic testing, and need of the better understanding of fetal anatomical anomalies, especially when presenting in a set. Early pregnancy screening could be very effective and give the opportunity and time the parents to make a good decision. Using multimarker screening of trisomy 18 may improve the detection rate up to 95-99%. These markers should have to implement to the screening protocols.