Screening for aneuploidy: the genetic sonogram

Prenatal diagnosis and pregnancy outcome analysis of thickened nuchal fold in the second trimester

To summarize the results of prenatal diagnoses and pregnancy outcomes of fetuses with thickened nuchal fold (TNF) in the second trimester.From 2009 to 2016, we studied 72 pregnant women with fetal nuchal fold (NF) measurements over 5 mm at 14 to 19 + 6 weeks or 6 mm at 20 to 28 weeks of gestation who received prenatal diagnosis. Karyotypes were first used to detect common chromosomal diseases, and then chromosome microarray analysis (CMA) was performed if karyotypes were normal. Prognoses were followed up by documentation in the hospital or over the telephone.In total, 12 fetuses with chromosomal defects, including 5 pathogenic copy number variants (CNVs) were detected. The risk of chromosomal defects when a TNF was associated with structural malformations (SMs) (35.5%) was much greater than that of an isolated TNF (3.7%) and a TNF associated with soft markers (0%). The rate of SMs when the NF measured ≥10 mm was greater than that NF measured 5 to 7.9 mm or 8 to 9.9 mm. Totally 27 fetuses had adverse pregnancy outcome.A TNF is not only associated with a high risk of trisomy 21 but also with other chromosomal abnormalities, including pathogenic CNVs. The rates of SMs and adverse outcomes increase when the NF thickness increases.

Second trimester ultrasound markers of fetal aneuploidy

Although it is widely accepted that the best time to screen for chromosomal abnormalities is the first trimester, ultrasound evaluation of the fetus in the second trimester has also been shown to be useful for this purpose. A multitude of markers of varying strength has been developed over the past 30 years. In addition, the optimal time to diagnose fetal anomalies with confidence is also the mid second trimester. Therefore, performance of obstetrical ultrasound at this point in gestation continues to be an important component of prenatal care.

Isolated choroid plexus cyst or echogenic cardiac focus on prenatal ultrasound: is genetic amniocentesis indicated?

OBJECTIVE

The purpose of this study was to determine whether or not genetic amniocentesis is warranted when isolated choroid plexus cysts (CPC) or echogenic cardiac foci (EF) are noted on prenatal ultrasound.

STUDY DESIGN

We performed a retrospective analysis on patients from our perinatal database. All obstetric patients with CPC or EF noted on second-trimester perinatology ultrasound from April, 1998 to November, 2004 were included. Information regarding ultrasound findings and neonatal outcome were analyzed.

RESULTS

During the study period, 515 patients with CPC or EF were evaluated. Of these, 429 (83.3%) had isolated CPC or EF and 86 (16.7%) had additional risk factors. The incidence of abnormal karyotype was 0 versus 2.3%, respectively (P = .03). The additional risk factors considered were: advanced maternal age, abnormal serum triple marker screening, and/or other abnormal ultrasound findings. Furthermore, during the study period there were 20,122 live births and 27 (0.1%) cases of aneuploidy diagnosed postnatally. Of these, none had isolated CPC or EF on prenatal ultrasound.

CONCLUSION

CPC or EF noted on prenatal ultrasound warrants referral for careful consultative ultrasound evaluation. In the absence of other risk factors, however, genetic amniocentesis for isolated CPC or EF does not appear to be necessary.

Ultrasound Findings After Screening for Down Syndrome Using the Integrated Test

OBJECTIVE

To evaluate the incidence and significance of fetal anomalies and "soft markers" after screening for Down syndrome using the integrated test.

METHODS

This study is a retrospective study of 2,332 women at University College London Hospitals, United Kingdom. All women were screened for Down syndrome by the integrated test. Subsequently, a detailed anomaly scan was performed. All scan reports and screening results were analyzed statistically using SPSS 11.0 software.

RESULTS

Sixty-eight (2.9%) patients were categorized as high risk. There were 12 cases affected by Down syndrome, 10 (10 of 68) in the high-risk group and two (two of 2,264) in the low-risk group. Soft markers or structural anomalies were found in 13.0% of the low-risk group, in 29.4% of the high-risk group, and in 50% of the fetuses affected by Down syndrome. Multiplying the likelihood ratio of each marker with the risk of Down syndrome from the integrated test reduced the false-positive rate of the integrated test from 2.5% to 1.8%, but was accompanied by a reduction in the detection rate from 83% to 75%.

CONCLUSION

Absence of structural anomalies or markers should not prevent offering karyotyping to women in the high-risk group, because this would result in a significant reduction in the detection rate of Down syndrome. Women screened as low risk by the integrated test who have isolated soft markers should not be offered an amniocentesis.

[Autopsy findings related to Down's syndrome: 101 cases]

OBJECTIVES

To analyze the spectrum of congenital malformations among fetuses with Down's syndrome sent for necropsy. Materials and methods. Necropsies following medical termination of pregnancy during the second and third trimester were performed during a 4 year period.

RESULTS

The incidence of each malformation was determined. Talipes equinovarus and aberrant lobation of the lung were present in 6% of cases. We are able to state precisely the incidence of 11 pairs of ribs: 11%.

CONCLUSION

A precise knowledge about Down's syndrome associated malformations is essential for genetic counselling. The exact incidence of each sign is important to lead ultrasound examination when this syndrome is revealed.