First Trimester Down’s Syndrome Screening Shows High Detection Rate for Trisomy 21, but Poor Performance in Structural Abnormalities – Regional Outcome Results

Abstract

Objective: To evaluate whether first trimester screening markers are altered in pregnancies affected both by other chromosomal defects than trisomy 21 and structural anomalies and whether it is possible to detect these pregnancies by combined ultrasound and biochemical screening test. Methods: Altogether 4,776 singleton pregnancies underwent first trimester screening. Of them, 3,101 women were screened using a combination of maternal serum free hCG, pregnancy-associated plasma protein A and nuchal translucency and 1,361 women with first trimester biochemistry without ultrasound. Nuchal translucency screening was performed between the 11th and 13+6th gestational weeks, and biochemistry 1–2 weeks earlier. Results: Using a fixed cut-off rate of 1:250 for Down’s syndrome, the detection rate of trisomies 21, 18 and 13 were 92, 67 and 0%, respectively. All open defects, 85% of cardiac defects and other minor defects were not detected in first trimester screening. Majority of these structural abnormalities occurred in women under 35 years of age. Conclusion: First trimester Down’s syndrome screening is effective in trisomy screening, but its performance in structural abnormalities is low, when used as a part of routine clinical practice. We conclude that it is too early to drop second trimester screening ultrasound entirely from antenatal care programs if a high detection rate is to be achieved also in structural defects.

Nuchal translucency and major congenital heart defects in fetuses with normal karyotype: a meta‐analysis

“…Among those, 32 were excluded from further analysis, and five more were excluded because they expressed NT cut‐offs as absolute values. Therefore, 20 studies were used for data synthesis (Tables S1 and S2; Figure S). The assessment of quality and risk of bias of the included studies is presented in Table S3.…”

“…Thirteen studies (180 619 fetuses; 441 with major CHDs) provided data for NT > 99 th centile. The pooled sensitivity and specificity of NT > 99 th centile was 19.5 (95% CI, 15.9–23.5) and 99.1% (95% CI, 99.1–99.2), respectively (Figure ).…”

Pentasomy 49,XXXXY Diagnosed in utero: Case Report and Systematic Review of Antenatal Findings

“…In their study, Rissanen et al [20] tried to evaluate whether first-trimester screening markers are altered in pregnancies affected by other chromosomal defects than trisomy 21 and structural anomalies. The authors concluded that a first-trimester screening test is effective in trisomies screening but has a poor performance in detecting structural anomalies.…”

‘Normal’ nuchal translucency: a justification to refrain from detailed scan? Analysis of 6858 cases with special reference to ethical aspects

“…Up to now, numerous articles address the detection ability of ultrasonography for major anatomical and chromosomal abnormalities of fetuses with ‘increased’ NT. Several articles include the evaluation of fetuses with ‘increased’ and ‘normal’ NT . However, the scientific workup of prevalence and detection rate of major anomalies in fetuses with ‘normal’ NT seems to be limited …”

“…Several articles include the evaluation of fetuses with 'increased' and 'normal' NT. [24][25][26][27][28] However, the scientific workup of prevalence and detection rate of major anomalies in fetuses with 'normal' NT seems to be limited. 28 The main aim of this study is to disclose the frequency of major anomalies in fetuses with 'normal' NT.…”