How Effective Is First-Trimester Screening for Trisomy 21 Based on Ultrasound Only?

Abstract

Objective: To evaluate the most common first-trimester ultrasound features of fetuses with trisomy 21 (T21) and to examine the screening performance for Down syndrome (DS) using only ultrasound-based protocols. To investigate whether maternal age (MA) has an impact on the efficacy of the ultrasound-based screening methods. Methods: In a prospective study, 6,265 patients were examined. Two ultrasound-based risk calculation protocols were applied: ‘NT' (based on nuchal translucency) and ‘NT+' (based on NT and secondary markers). Results: A total of 5,696 patients were enrolled for analysis; 84 subjects with T21 were identified. Combinations of abnormal ultrasound markers were observed in only 1.2% of euploid fetuses compared to 71.5% of fetuses with T21. Among 17.9% of DS cases with cardiac anomaly, 14.3% comprised atrioventricular septal defects. For a false-positive rate of 3%, the detection rates of T21 were 73.8 and 91.7% for the ‘NT' and ‘NT+' protocols, respectively. The efficacy of both methods was affected by MA. Conclusions: Most of the fetuses with DS demonstrate a combination of ultrasound markers of aneuploidy in the first trimester. The ‘NT+' protocol is efficient and provides comparable performance as a combined screening test. It is a valuable method, especially when the access to biochemical analysis is restricted.

The Value of Detailed First-Trimester Ultrasound Anomaly Scan for the Detection of Chromosomal Abnormalities

“…Whereas a higher incidence of cardiac defects compared to euploid fetuses is well documented in fetuses with trisomy 21 [17,18], less data is available regarding additional structural abnormalities detected during the first trimester. Wiechec et al reported an incidence of 4.8 % for extracardiac structural abnormalities and an incidence of 17.9 % for cardiac anomalies in fetuses affected with trisomy 21 [19]. Among fetuses with trisomy 21, we identified only one case (1.3 %) with an extracardiac defect (abdominal wall and gastrointestinal tract), 33.3 % had a cardiac defect.…”

First trimester combined screening for fetal aneuploidies enhanced with additional ultrasound markers: an 8-year prospective study

“…Thus, at a 5% FPR, Abele et al [13] reached a DR for T21 of 97.5%, while Wiechec et al [11,12] achieved a DR of 94-95%. Finally, our T21 detection rate was much higher than that of the triple test, which has been found to be around 70%, and higher than that of the quadruple test, which has an overall detection rate of approximately 80% [21,22].…”

“…Few studies have examined the screening performance when all additional markers are assessed together. Using an ultrasound only based protocol, with NT and all additional markers, for a FPR of 5%, the detection rate for T21 reached 94-97.5% [11][12][13]. When all of these markers were added to a traditional combined test, the detection rate substantially increased to up to 100%, for a FPR of 2.4% [14] or 3.4% [15].…”

Observational study comparing the performance of first‐trimester screening protocols for detecting trisomy 21 in a North Indian population

“…Screening using a cut‐off value of nuchal translucency above the 95th percentile for a given CRL was also examined; this improved the detection rate to 62.5%, with a false‐positive rate of 4.0%. A recent study in Poland reported a detection rate of 73% with a false‐positive rate of 3% by applying a similar method (combined with maternal age). This approach is superior to using a fixed nuchal translucency cut‐off value.…”

“…Studies have reported that the addition of ultrasonography markers to nuchal translucency increases detection rates for aneuploidies . A recent study has even reported a 100% trisomy‐21 detection rate using combined screening (maternal age, β‐hCG, PAPP‐A, nuchal translucency, nasal bone, ductus venosus, and tricuspid regurgitation).…”