Clinical results after the implementation of cell-free fetal DNA detection in maternal plasma

Indigenization of the median of markers for Down syndrome screening based on statistical analysis of medical big data

OBJECTIVE

To indigenize the median of Down syndrome (DS) screening markers for first and second trimester, and compare the impact of the indigenized and built-in median data on the efficiency of DS screening.

MATERIALS AND METHODS

Data derived from first and Second-trimester screening (FTS and STS) for DS, composed of selected pregnancies deemed to be normal, were examined in a retrospective study. Indigenization regression analysis was calculated by using five models to fit statistical the raw data. Multiple of median (MoM) values estimated by using indigenized medians were compared with those calculated by using built-in.

RESULTS

This study established a regression equation which is more suitable for the median of each screening marker in the local pregnant women. The changes of median MoM of screening markers were statistically significant after indigenization. For FTS, the detection rate was 100% when the false positive rate was 5%, and the cut-off value was 1/262. On the other hand, for STS, the detection rate of the model with indigenized parameters was 77.42%, which is 16.13% higher than that of built-in parameters.

CONCLUSION

For the individual specific risk of pregnancy, when the indigenized parameters was used to calculate, is more accurately and screening effectiveness has been improved. This is a great reference significance for the current prenatal screening whether indigenized data should be used.

Impact of cell-free fetal DNA on early invasive prenatal diagnosis at a Chinese reference maternal medicine center

Purpose: The aim of this study is to evaluate the impact of the utility of maternal cell-free DNA (cfDNA) on the number of chorionic villus sampling (CVS) at a mainland Chinese maternal hospital.Methods: This was a retrospective cohort study conducted in consecutive singleton pregnancies that underwent CVS between the 11th and 14th gestational weeks at a Chinese maternal hospital during a nine-year period. The indications, complications and prenatal diagnosis results were evaluated.Results: This study consisted of 5108 CVS procedures, including 2000 performed for fetal karyotyping, and 3108 performed for fetal single-gene genotyping. During the period with the introduction of cfDNA, the proportion of the number of CVS procedures for the indication of positive serum screening declined significantly, and abnormal ultrasound was the main indication for CVS performed for fetal karyotyping. Thalassemia was always the main indication for CVS, accounting for 50.5% of all CVS cases.Conclusions: cfDNA has changed the spectrum of CVS indications. CVS is now the invasive procedure performed for patients with a fetus having a very high risk of fetal genetic defects, including fetuses having major abnormal ultrasound or having a risk of single-gene disorder inherited from their parents.

A two-year experience of non-invasive prenatal testing (NIPT) at an urban tertiary medical center in South Korea

OBJECTIVE

To report our experience of implementing non-invasive prenatal testing (NIPT) in a tertiary urban academic medical center in South Korea.

MATERIALS AND METHODS

An observational retrospective study of singleton and twin pregnancies that underwent prenatal screening for fetal aneuploidy from July 2016 to April 2018 was conducted. Demographics of the study population electing NIPT versus those opting the integrated test were compared. We also assessed clinical significant factors influencing cfDNA fetal fraction in NIPT.

RESULTS

Among the 817 women who underwent serum screening tests during the study period, 490 women (60.0%) chose the integrated test while 327 women (40.0%) chose NIPT. Compared to the integrated test group, women in the NIPT group were older (mean age 34.7 ± 3.7 vs. 32.6 ± 3.4; p-value < 0.01), multiparous (47.1% vs. 39.8%; p-value = 0.046), and had higher rate of previous abortion history (28.4% vs. 21.6%; p-value = 0.033). A significant decrease in the number of invasive diagnostic tests was observed since the adoption of NIPT. The screen negative and positive rates of the integrated test group for fetal aneuploidy were 95.3% and 4.7%, respectively while those of the NIPT group were 95.9% and 1.2%, respectively. The rate of inadequate cfDNA fetal fraction was 3.0%. Low fetal fraction was associated with higher maternal age, body weight and BMI.

CONCLUSIONS

The implementation of NIPT has significantly affected the practice pattern of prenatal aneuploidy screening by replacing the integrated test and decreasing invasive diagnostic tests.

Impact of cell-free fetal DNA on invasive prenatal diagnostic tests in a real-world public setting

Objective To evaluate the impact of cell-free fetal DNA (cfDNA) test on the number of invasive tests carried out in a public hospital that does not include this test in its services. Methods This was a retrospective cohort study in singleton pregnancies with a high risk (>1:270) on the first-trimester screening for aneuploidies. The options of performing an invasive test or a cfDNA test were explained to all women, the latter being especially recommended to those with a 1:50-1:270 risk (Group 1). If the risk was >1:50 (Group 2), or nuchal translucency (NT) was >99th percentile or there were major malformations (Group 3), invasive test was recommended. Results A total of 755 of 14,398 (5.2%) cases had a high-risk first-trimester screening, of whom 46 cases were excluded due to incomplete follow-up. In the remaining 709 cases, the percentage of aneuploidies was 9.9% (70 cases) and 110 opted for a cfDNA test (15.5%). There were two true-positive results of cfDNA (one in Group 2 and another in Group 3). In Group 1, 67.4% [95% confidence interval (CI) 60.0%-72.1%, P < 0.01] fewer invasive procedures were performed in those who opted for a cfDNA test, without having false negatives. Conclusion Pregnant women with a 1:50-1:270 risk who opt for cfDNA save two out of three invasive tests, without affecting the aneuploidy detection rate.