Noninvasive first-trimester screening for fetal aneuploidy

What can be inferred if the fetal increased nuchal translucency thickness changes?

Objectives: To study the perinatal outcomes in the women who's the different changes of an increased fetal nuchal translucency thickness.Methods: Since 2013-2016, the pregnant women whose initial measurement of fetal nuchal translucency (NT) ≥ 3.5 mm would be invited to scan the NT again after a week. Between the two measurements over 1 mm, defined as "change". According to different results between two measurements, they were divided into three groups: unchanged group, thinned group and thicken group. To follow-up and compare the perinatal outcomes among the three groups.Results: One hundred seventy-five cases met our criteria and were retrieved in the study. There are 90 cases of the unchanged group, 60 cases of the thinned group and 25 cases of thicken group. Among three groups, the chromosomal abnormalities rate is 11.11, 21.67, and 60.0% respectively, the structure abnormalities rate is 10.0, 8.51, and 20.0%, the normal delivery rate is 76.67, 70.0, and 28.0%. There all have the significantly differences in statistics except the structure abnormalities rate.Conclusion: The chromosomal abnormalities rate and adverse perinatal outcome rate were worse if NT continues to thicken. However, the perinatal outcome of the NT thinned group is no better than the NT unchanged case.

Echogenic intracardiac focus in 2nd-trimester fetuses with trisomy 21: usefulness as a US marker

PURPOSE

To determine whether there is a relationship between the presence of an echogenic intracardiac focus in 2nd-trimester fetuses and trisomy 21 (Down syndrome).

MATERIALS AND METHODS

A complete genetic ultrasonographic (US) scan was obtained in 3,303 consecutive fetuses with an estimated gestational age of 14.0-24.0 weeks (mean +/- SD, 17.1 weeks +/- 1.75). US was performed in a prospective fashion without any knowledge of karyotype and included assessment of any potential echogenic intracardiac focus (ie, calcified papillary muscle). Karyotypes were obtained in all fetuses. Maternal ages ranged from 13.0 to 47.4 years (mean, 35.1 years +/- 5.1). The prevalence of Down syndrome in this population was 1.6% (53 of 3,303 fetuses).

RESULTS

An echogenic intracardiac focus was seen in 147 of the 3,192 karyotypically normal fetuses (4.6%) and 16 of the 53 fetuses with trisomy 21 (30%). The positive predictive value (PPV) of an echogenic intracardiac focus in this high-risk population was 9.8%; sensitivity, 30%; specificity, 95%; likelihood ratio, 6.6; and relative risk (RR), 8.2 (P <.001). For a sonographically isolated echogenic intracardiac focus, the PPV was 3.7%; sensitivity, 19%; specificity, 95%; likelihood ratio, 4.2; and RR, 4.8 (P =.002).

CONCLUSION

A sonographically isolated echogenic intracardiac focus (no other anomalies or markers noted on a complete genetic sonogram) was associated in our high-risk population with a 4.8-fold (95% CI: 1.8, 12.5) increase in RR for trisomy 21 (P =.002).

The "genetic sonogram": comparison of the index scoring system with the age-adjusted US risk assessment

PURPOSE

To compare two ultrasonographic (US) methods for prenatal detection of fetal Down syndrome.

MATERIALS AND METHODS

Genetic amniocentesis was successfully performed in 3,303 consecutive women with high-risk pregnancies (mean gestational age, 17.1 weeks). All patients underwent a complete "genetic US" examination prospectively. Risk was assessed by using (a) various modifications of the index scoring system (ISS) and (b) the age-adjusted US risk assessment (AAURA).

RESULTS

The prevalence of Down syndrome in this population was 1.6% (53 of 3,303). By using a threshold of at least 2 points to detect trisomy 21, the best ISS had a sensitivity of 45.3%, false-positive rate of 4.9%, likelihood ratio of 9.3, and positive predictive value in the high-risk population in this study of 13.3%. Lowering the threshold to 1 point increased the sensitivity to 60.4% but increased the false-positive rate to 15.8%. Adding points for age increased the sensitivity to 67.9% but increased the false-positive rate to 24.3%. Results of using AAURA to detect trisomy 21 were nearly identical, with a sensitivity of 43.4% and false-positive rate of 4.9% at a 1 in 36 risk threshold and a sensitivity of 69.8% and false-positive rate of 26.1% at a 1 in 200 threshold. Trisomies 18 and 13 were detected with sensitivities of 80.0% and 100.0%, respectively, with either system.

CONCLUSION

The modified ISS and AAURA are equivalent in screening for Down syndrome, with detection of approximately half of all trisomy 21 fetuses at a 5% false-positive rate.