First and Second-Trimester Screening, for Down's Syndrome: An Umbrella Review on Meta-Analyses.

BACKGROUND AND AIM: Despite the variety of screening tests, the number of babies born with Down's syndrome (DS) has not significantly decreased. The aim of this study was systematically review previously published meta-analysis studies to identify the most efficient screening tests for DS during only the first trimester (FT) and only in the second trimester (ST) of pregnancy.

METHODS

The data sources, including Scopus, Cochrane Library, and PubMed, were reviewed. The effectiveness of tests was investigated and compared by extracting their sensitivity and specificity values from meta-analyses. The heterogeneity of data was investigated by χ 2 and I 2 tests. In addition, publication bias was assessed through Egger's and Begg's tests.

RESULTS

This study investigated 14 eligible and high-quality meta-analyses. Meta-analysis of 13 studies revealed FT and ST as the best stage for conducting serum tests, with a sensitivity of 0.824 (CI: 0.790-0.857) and specificity of 0.956 (CI: 0.947-0.965). Likewise, FT and ST were found as the best stage for conducting ultrasound tests, with a sensitivity of 0.882 (CI: 0.850-0.914) and a specificity of 0.95 (CI: 0.944-0.956). In addition, ST was determined as the best stage for carrying out ultrasound (US) and serum screening (SS) tests, with a sensitivity of 0.93 and a specificity of 0.93, indicating the highest sensitivity and specificity of US + SS tests in the ST than FT and FT & ST stages.

CONCLUSION

The first and second trimesters (FT and ST) is the best stage for carrying out ultrasound and serum screening tests. ST was found to be the best stage for conducting US + SS in DS screening tests. US + SS tests achieved the best results for DS screening during the FT and ST of pregnancy.