Current controversies in prenatal diagnosis 3: is there still a value in a nuchal translucency screening ultrasound in conjunction with maternal plasma non-invasive cell-free DNA testing?

First Trimester Screening for Fetal Aneuploidies Using Placental Growth Factor: The Great Obstetrical Syndrome (GOS) Study

OBJECTIVE

This study sought to estimate the ability of first trimester maternal serum placental growth factor (PlGF) to identify fetal aneuploidies.

METHODS

A prospective cohort study of singleton pregnancy at 11 to 13 weeks was conducted. Maternal serum PlGF concentration was measured using BRAHMS PlGF plus KRYPTOR automated assays (Thermo Scientific BRAHMS, Hennigsdorf, Germany). PlGF and nuchal translucency were log-transformed and reported as multiples of the median (MoM) adjusted for crown-rump length. Detection rates were calculated using receiver-operator characteristic curves.

RESULTS

The study observed 21 cases of fetal aneuploidies (0.4%) out of 4765 participants. Trisomy 21 (13 cases; 0.85 MoM; interquartile range [IQR] 0.80-0.93), trisomy 18 (two cases; 0.77 MoM; IQR 0.66-0.87) and trisomy 13 (two cases; 0.68 MoM; IQR 0.61-0.75) were associated with low PlGF concentrations. The low PlGF values observed in the cases of monosomy X (two cases; 0.85 MoM; IQR 0.82-0.88, P = 0.05), triploidy (0.78 MoM, P = 0.11), and 47,XX,i(22)(p10) (0.18 MoM, P = 0.08) were not statistically different from the controls. A model including maternal age, nuchal translucency, and PlGF could have identified all (95% CI 83%-100%) cases of trisomy 21 and six of the other fetal aneuploidies (75%) at a false-positive rate of 9%.

CONCLUSION

Low first trimester PlGF is associated with an increased risk of fetal aneuploidy. PlGF combined with first trimester ultrasound (nuchal translucency, uterine artery Doppler, and early fetal anatomy) could identify not only women at high risk for preeclampsia, but also fetuses at high risk of aneuploidy for optimal further testing (non-invasive testing for common aneuploidy screening or chorionic villus sampling for full screening and diagnosis).

Chromosomal Microarray Analysis versus Karyotyping in Fetuses with Increased Nuchal Translucency

We have carried out a retrospective study of chromosome anomalies associated with increased nuchal translucency (NT) in order to compare yield rates of karyotype, chromosome microarray analysis (CMA), and non-invasive prenatal testing (NIPT) in this condition. Presenting with increased NT or cystic hygroma ≥3.5 mm as an isolated sign, 249 fetuses underwent karyotype and/or CMA from 11 to 18 gestational weeks. Karyotype and fluorescence in situ hybridization (FISH) analyses detected 103 chromosomal anomalies including 95 aneuploidies and eight chromosomal rearrangements or derivatives. Further, seven pathogenic copy number variants (CNV), five likely pathogenic CNVs, and 15 variants of unknown significance (VOUS) were detected by CMA in fetuses with normal karyotype. Genetic testing is now facing new challenges due to results with uncertain clinical impacts. Additional investigations will be necessary to interpret these findings. More than 15% of the anomalies that we have diagnosed with invasive techniques could not be detected by NIPT. It is therefore definitely not recommended in the case of ultrasound anomalies. These results, while corroborating the use of CMA in fetuses with increased NT as a second tier after rapid aneuploidy testing, do not suggest a dismissal of karyotype analysis.

The effect of progesterone use in the first trimester on fetal nuchal translucency

Objective:

To evaluate the possible association between progesterone use in the first trimester of pregnancy and fetal nuchal translucency (NT).

Material and Methods:

This is an observational case-control study, which was conducted with patients who underwent nuchal scans between March 2015 and February 2016 and consequently delivered live and healthy babies. The study group was composed of assisted reproductive technology pregnancies and used intravaginal progesterone 180 mg/day until gestational week 12. The control group comprised pregnant women who became pregnant spontaneously without using any progesterone preparation in the first trimester.

Results:

One hundred sixty-four (57.5%) of 285 patients were in the control group and 121 (42.5%) were in the progesterone group. Age, bodyweight, gravidity, and parity number of previous births and abortus, gestational week, crown-rump lengths, free β-human chorionic gonadotropin, pregnancy-associated plasma protein A, and NT values of the progesterone and control groups were recorded and we investigated whether there was a statistically significant difference between the two groups in terms of these parameters; maternal weight was found to be higher in the progesterone group than in the control group and the difference between the groups was statistically significant (p=0.019 and p=0.025). Whether the difference in NT was caused by the effect of maternal weight was investigated using the covariance analysis test and maternal weight was not found to be statistically significant in the model (p=0.284).

Conclusion:

Fetal NT was increased in the progesterone group compared with the untreated group in healthy pregnancies.

Systematic review and meta-analysis of the performance of second-trimester screening for prenatal detection of congenital heart defects

BACKGROUND

The prenatal detection rate of congenital heart defects (CHDs) is increasing, but reported rates vary.

OBJECTIVES

To determine the performance of the second-trimester anomaly scan to detect CHD.

SEARCH STRATEGY

PubMed and Embase were searched for relevant studies in any language from inception to February 3, 2017. The search terms included "prenatal diagnosis" or "pregnancy," "cardiovascular diseases" or "cardiac defects," "congenital," and "specificity," or "sensitivity," or "cohort study."

SELECTION CRITERIA

Cohort studies assessing the detection rate of CHD during population-based prenatal screening from 1995 were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Data were collected from identified studies; authors were approached for additional data when necessary. A review and meta-analysis were performed. When possible, separate analyses were undertaken for isolated CHD cases.

MAIN RESULTS

Meta-analysis of seven studies showed the pooled detection rate of CHD in unselected populations as 45.1% (95% confidence interval 33.5%-57.0%). However, the rate of detection of univentricular defects and heterotaxy was above 85%. Similar rates were found among cases of isolated CHD.

CONCLUSIONS

Prenatal detection showed a strong correlation with CHD severity. The detection of conotruncal anomalies needs to improve. A thoroughly organized screening program will be essential to achieve a higher detection rate.