Ultrasonographic Findings of Fetal Aneuploidies in the Second Trimester – Our Experiences

Abstract

Objectives: The aim of this study was to determine the incidence of ultrasound findings in common fetal chromosomal defects on a relatively large series coming out from one institution. We also tried to evaluate possible clusters of ultrasound signs of major chromosomal defects. Methods: Of the 22,150 fetal karyotypings, 514 abnormal karyotypes (2.3%) were diagnosed prenatally between 1990 and 2004. Of them, 374 were further evaluated for abnormal ultrasound signs in this study. These represented the major chromosomal defects of Down syndrome (n = 207), trisomy 18 (n = 70), trisomy 13 (n = 28) and Turner syndrome (n = 69). Results: The incidences of major structural defects and minor anomalies were evaluated then sonographic signs with the highest incidences were established in each of the major chromosomal defects. In fetuses with trisomy 13, besides cardiac defects, the most frequently seen structural abnormalities were central nervous system anomalies and facial anomalies. In fetuses with trisomy 18 and trisomy 21, cardiac anomalies were the most common structural sonographic features, whereas the most common findings were hygroma colli and fetal hydrops in fetuses with Turner syndrome. As far as minor anomalies are concerned, increased nuchal fold was the most predictive marker of each major aneuploidy. Choroid plexus cysts were more common in trisomy 18, whereas echogenic intracardiac foci were more frequently detected in fetuses with trisomy 13 and trisomy 21. Conclusion: This study may help to select the most predictive components of the genetic sonogram which may assist the counseling of women for the actual risk of the major chromosomal abnormalities.

Prevalência das malformações congênitas identificadas em fetos com trissomia dos cromossomos 13, 18 e 21

“…As principais malformações descritas foram: holoprosencefalia (39%), outras anormalidades do SNC (58%), anormalidades faciais (48%), renais (33%) e cardíacas (48%) 9 . Da mesma forma, em outro estudo, demonstrou-se que fetos com trissomia do cromossomo 13 apresentavam frequentemente defeitos cardíacos, anomalias faciais e do SNC 10 . A holoprosencefalia encontra-se associada à onfalocele em aproximadamente 40% dos casos de trissomia 13, e as anomalias faciais também a acompanham, principalmente os defeitos de linha média, como hipotelorismo, fendas labiopalatinas, narina única, probóscide e ciclopia 11,12 .…”

“…Dentre as descritas, sabe-se que fetos com trissomia do cromossomo 21 mostram elevada incidência de malformações cardíacas, podendo chegar a 65% em alguns estudos, principalmente defeitos septais 11 . Entre os casos de trissomia do cromossomo 21, o achado ultrassonográfico mais comum foi a cardiopatia 10 . Outras malformações fortemente associadas à trissomia do cromossomo 21 são: hidrocefalia, hipoplasia cerebelar, atresia de duodeno, onfalocele e anomalias de membros 11 .…”

“…A taxa para detecção de anomalias fetais relacionadas diretamente ao diagnóstico de cromossomopatias depende essencialmente da qualificação e experiência dos ultrassonografistas, da qualidade dos ecógrafos e do nível e duração dos exames ultrassonográficos obstétricos 10 . Corroborando esta ideia, em estudo sobre o diagnóstico pré-natal de anormalidades cromossômicas, por meio de testes invasivos, verificou-se que a maioria dos casos de alterações em cariótipos fetais foi encontrada no grupo encaminhado por malformações identificadas em ultrassonografias 25 .…”

Prenatal Diagnosis of Prevalence of the Right Heart

“…In our study, the fetuses with intracardiac anomalies were divided into 2 groups according to the presence or absence of coexisting extracardiac defects. The fetuses with chromosomal anomalies usually had multiple‐system involvement, 17 which may be the reason why the fetuses with both extracardiac and intracardiac defects had a much higher risk of abnormal karyotypes. However, the survival rates in these groups were not significantly different ( P = .407); even when excluding cases undergoing termination of pregnancy and selective reduction, the adjusted survival rates were approximately similar ( P = .539).…”

An algorithm for the prenatal detection of chromosome anomalies by QF‐PCR and G‐banded analysis

“…Noninvasive screening, using first and second trimester tools, such as sonographic markers and maternal serum biochemical markers, has gained popularity in recent years due to the low false positive rate (2-5%) and high detection rates for Down syndrome and other aneuploidies (Benn et al, 2005;Schiott et al, 2006;Bornstein et al, 2007;Breathnach et al, 2007;Jaques et al, 2007;Sheppard and Platt, 2007;Summers et al, 2007). High-level ultrasonography can also be used to identify pregnancies at increased risk (Verdin et al, 2000;Pinette et al, 2001;Devore and Romero, 2003;Benacerraf, 2005;Beke et al, 2008;Papp et al, 2008). For women assessed as having an increased risk of fetal aneuploidy, and who have opted for genetic amniocentesis, G-banded analysis of cultured amniotic fluid metaphase cells has been the gold standard test since its introduction in the mid 1970s.…”