What is the importance of second-trimester "soft markers" for trisomy 21 after an 11- to 14-week aneuploidy screening scan?

Chromosomal Abnormalities Detected by Chromosomal Microarray Analysis and Karyotype in Fetuses with Ultrasound Abnormalities

Objective

Chromosomal microarray analysis (CMA) is a first-line test to assess the genetic etiology of fetal ultrasound abnormalities. The aim of this study was to evaluate the effectiveness of CMA in detecting chromosomal abnormalities in fetuses with ultrasound abnormalities, including structural abnormalities and non-structural abnormalities.

Methods

A retrospective study was conducted on 368 fetuses with abnormal ultrasound who received interventional prenatal diagnosis at Meizhou People's Hospital from October 2022 to December 2023. Samples of villi, amniotic fluid, and umbilical cord blood were collected according to different gestational weeks, and karyotype and CMA analyses were performed. The detection rate of chromosomal abnormalities in different ultrasonic abnormalities was analyzed.

Results

There were 368 fetuses with abnormal ultrasound, including 114 (31.0%) with structural abnormalities, 225 (61.1%) with non-structural abnormalities, and 29 (7.9%) with structural combined with non-structural abnormalities. The detection rate of aneuploidy and pathogenic (P)/likely pathogenic (LP) copy number variations (CNVs) of CMA in fetuses with structural abnormalities was 5.26% (6/114), the detection rate of karyotype was 2.63% (3/114), and the additional diagnosis rate of CMA was 2.63%. In the fetuses with ultrasonic non-structural abnormalities, the detection rate of karyotype was 6.22% (14/225), the detection rate of aneuploidy and P/LP CNVs in fetuses with ultrasonic structural abnormalities was 9.33% (21/225), and the additional diagnosis rate of CMA was 3.11%. There was no significant difference in chromosome abnormality detection rate of CMA among structural abnormality, non-structural abnormality, and structural abnormality combined with non-structural abnormality groups (5.3%, 9.3%, and 13.8%, p = 0.241), also among multiple ultrasonic abnormality and single ultrasonic abnormality groups (14.8%, and 7.3%, p = 0.105).

Conclusion

CMA can significantly improve the detection rate of genetic abnormalities in prenatal diagnosis of ultrasonic abnormal fetuses compared with karyotype analysis. CMA is a more effective tool than karyotyping alone in detecting chromosomal abnormalities in fetuses with ultrasound abnormalities.

Application of Copy Number Variation Sequencing Technology in 422 Foetuses with Abnormal Ultrasound Soft Markers

Purpose

The application value of ultrasound soft indicators in prenatal diagnosis was evaluated by copy number variation sequencing (CNV-seq).

Methods

The authors conducted a retrospective analysis of 422 pregnant women who underwent CNV-seq testing at Luoyang Maternal and Child Health Hospital between January 2020 and November 2021. The women had presented with abnormal ultrasound soft markers; those identified as high-risk through non-invasive prenatal screening were excluded.

Results

A total of 43 abnormal cases were detected in 422 pregnant women, including 24 aneuploidy (including chimerism) and 19 pathogenic or likely pathogenic copy number variations (CNVs). Based on the characteristics of ultrasound soft indicators, pregnant women were divided into five groups: isolated nuchal translucency (NT) group, combined NT group, isolated soft indicators group, combined soft indicators group and combined non-NT group. The abnormality detection rates in the five groups were 12.38% (13/105), 36.11% (13/36), 3.74% (4/103), 3.08% (2/63) and 10.09% (11/109), respectively. Statistical tests showed that the detection rate in the NT thickening combined with other abnormalities group was significantly higher than the other four groups, while there was no statistical difference in the detection rate among the other four groups.

Conclusion

When NT thickening is combined with other abnormalities, it is more likely to indicate chromosome abnormalities or CNVs, so it should be regarded seriously upon finding, and pregnant women should be referred for prenatal diagnosis according to the examination results. In addition, NT thickening is an important indicator for prenatal diagnosis and should be considered regardless of whether it occurs independently. The authors recommend CNV-seq for prenatal diagnosis to prevent missing small fragments of CNVs during traditional karyotyping.

Nasal bone in fetal aneuploidy risk assessment: are they independent markers in the first and second trimesters?

OBJECTIVES

In the mid-trimester ultrasound, nasal bone (NB) length can be used to correct the a priori risk for trisomy 21. Our study aims to evaluate if there is a correlation between an absent NB in the first trimester and a hypoplastic NB in the second trimester.

METHODS

Our two year retrospective analysis of data derived from routine clinical practice. Single euploid fetuses were included. The NB was assessed in both trimesters according to international guidelines and transformed into categorical variables. Logistic regression was performed in order to accomplish our main objective.

RESULTS

From the 759 normal pregnancies included, 45 (5.93%) had abnormal NB in the first trimester and 23 (3%) in the second trimester. Eleven cases (47.8%) of the abnormal NB in the second trimester were abnormal in the 11-14 weeks scan. After the diagnosis of an absent NB in the first trimester the odds ratio (OR) for a hypoplastic NB in the second trimester is 18.926 (7.791-45.977; p-value <0.01).

CONCLUSIONS

Our data suggest a strong association between the NB in the first and in the second trimester in normal euploid fetuses. This is important information to consider when counseling patients on the basis of this ultrasound marker.

ACR Appropriateness Criteria® Second and Third Trimester Screening for Fetal Anomaly

The Appropriateness Criteria for the imaging screening of second and third trimester fetuses for anomalies are presented for fetuses that are low risk, high risk, have had soft markers detected on ultrasound, and have had major anomalies detected on ultrasound. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

A Comprehensive Approach to Care of Women of Advanced Maternal Age

Advanced maternal age, historically defined as ages 35 years and older, is used to describe the later years in the female reproductive life span when rates of adverse pregnancy outcomes increase. The preconception period represents an opportunity to ensure the use of safe medications and optimize care for medical comorbidities. Routine prenatal care should be augmented with counseling on fetal aneuploidy with a detailed anatomic survey. Surveillance for preterm labor and preeclampsia is recommended. Growth assessment and antepartum testing for specific women are advised, particularly those ages 40 years and older and those with select medical problems. Despite an increased incidence of complications, most women of advanced maternal age will have normal pregnancies and will benefit from the compassionate care provided by midwives, advanced practice registered nurses (including nurse practitioners and clinical nurse specialists), and perinatal nurses.

Reference values of nuchal fold thickness in an Iranian population sample

Background:

Considering that ethnicity and gestational age (GA) could affect the value of nuchal fold thickness (NFT) in mid-trimester, we aimed to determine the reference intervals of NFT values for each gestational week from 16 to 24 weeks of pregnancy among a group of Iranian pregnant women.

Materials and Methods:

In this cross-sectional study, medical files of pregnant women who underwent fetal anomaly scanning at 16–24 weeks of gestation were reviewed and the following data were extracted: GA, value of NFT, value of nuchal translucency (NT) in their previous ultrasound study, if available, and head circumference (HC). The 5^th, 25^th, 50^th, 75^th, and 95^th percentiles of NFT for each gestational week were determined. The association between NFT and HC, GA, and NT were also determined.

Results:

Medical files of 882 pregnant women were studied. The expected 95^th percentile value of NFT between 16^th and 24^th weeks of gestation ranged from 4 mm to 5.9 mm. The mean (standard deviation) of NFT increased with GA from 2.67 (0.90) mm at 16^th weeks to 4.69 (0.71) mm at 24^th weeks. There was a significant positive association between NFT and GA (β = 1.11, p < 0.001), HC (β = 0.21, p < 0.001), and NT (β = 0.351, p < 0.001).

Conclusion:

The findings of this study revealed that before the 20^th week of gestation, the appropriate cutoff value of NFT is 5 mm, and for 21^st to 24^th weeks, the proper cutoff is 6 mm. However, for providing more conclusive results, further studies with larger sample size and considering the impact of other influencing variables are recommended.

Prenatal decision-making in the second and third trimester in trisomy 21-affected pregnancies

Down syndrome (DS) is the most common chromosome abnormality among live-born infants and the most frequent genetic cause of intellectual disability. The majority of pregnancies affected by DS are terminated. The decision concerning whether or not to continue a pregnancy following the prenatal diagnosis of DS is complex and amongst others, motivated by attitudes towards termination, socioeconomic factors, and ultrasound findings. In Germany, termination of pregnancy (TOP) is a legal option, even during the later stages of gestation. The aim of the present study was to evaluate the pregnancy outcomes as well as possible factors that influence the decisions made by women with trisomy 21-affected pregnancies. In our study 112 pregnancies affected by trisomy 21 were included. Our data confirm that most patients are more likely to terminate a trisomy 21-affected pregnancy [76 (67.9%) vs. 36 (32.1%) continued pregnancies]. Beyond that we found that women who continued their pregnancy tended to be at an advanced stage in their pregnancy at the time of karyotyping. With regards to factors from their medical history as well as sonographic findings there was no identifiable single factor that could distinguish between women that opted to continue or terminate their pregnancy.

Patient choice and clinical outcomes following positive noninvasive prenatal screening for aneuploidy with cell-free DNA (cfDNA)

OBJECTIVE

Evaluate patient choices and outcomes following positive cfDNA.

METHOD

Retrospective cohort study of women with positive cfDNA through two academic centers between March 2012 and December 2014. Patients were screened based on ACOG indications. Medical records reviewed for counseling, ultrasound findings, diagnostic testing, karyotype and outcome.

RESULTS

CfDNA was positive in 114 women; 105 singletons and 9 twin pairs. CfDNA was positive for autosomal trisomy (21, 18, 13) in 96 (84.2%) and sex chromosome aneuploidy in 18 (15.8%). Certified genetic counselors performed 95% of post-cfDNA counseling. Prenatal diagnostic testing was pursued by 71/114 (62%). Karyotype was available in 91/105 (86.7%) singletons and confirmed aneuploidy in 75/91 (82.4%); the PPV of cfDNA with any ultrasound finding was 93.6% versus 58.6% without a finding. An abnormal sonographic finding was seen in 4/16 (25%) singletons with false positive cfDNA. Fetal termination occurred in 53/79 (67%) singletons and 3/5 (60%) twins with prenatal abnormal or unknown karyotype for autosomal trisomy. Eleven fetuses (11/56, 19.6%) were terminated for suspected autosomal trisomy without karyotype confirmation.

CONCLUSION

Patient choices following positive cfDNA are varied. Ultrasound modifies the PPV of cfDNA. Termination rates for aneuploidy are not higher than historical controls. Recommendation for karyotype confirmation prior to termination is not universally followed. © 2016 John Wiley & Sons, Ltd.