Prenatal screening for chromosomal abnormalities and neural tube defects: How should this be done?
DOI:
https://doi.org/10.32385/rpmgf.v25i3.10628Keywords:
Prenatal Screening, Down Syndrome, Trisomy 18, Neural Tube DefectsAbstract
Objectives: Prenatal screening (PS) offers the advantage of determining, non invasively, the risk of trisomy 21, 18 and neural tube defects (NTD).There are still some doubts about its proper use.The objective of this review is to answer to the following: should PS be offered to all pregnant women Whats the best screening method Data Sources: Medline, Tripdatabase, Cochrane, National Guideline Clearinghouse, CMAinfobase, NeLH guidelines finder, UpToDate, IndexRMP. Review methods: Systematic review of articles published from 01-01-1999 to 25-08-2008) in English, Portuguese and Spanish, using the keywords «prenatal diagnosis» and «Down syndrome»,and «rastreio pré-natal» for the Portuguese site IndexRMP. The selection included 2 guidelines, 1 EBM guideline, 2 EBM reviews, 3 systematic reviews and 9 prospective studies.The results were classified with evidence levels according to the American Family Physician taxonomy. Participants:Women with spontaneous unifetal pregnancies Results: PS should be offered to all pregnant women presenting before 20 weeks of gestation, regardless of maternal age, after informed consent. Prenatal diagnosis should also be offered after proper information. Maternal age should not be used as a cutoff to offer PS or prenatal diagnosis. [C] Before 14 weeks of gestation the most effective and safe method is the full integrated test; if nuchal translucency measurement is not available, the serum integrated test is the next best choice. For women who want an early result there are two choices: the sequential screening (stepwise or contingent) or the first trimester combined test (in this case NTD screening should be offered in the 2nd trimester - alpha-fetoprotein measurement or ultrasound). Independent sequential screening is not recommended. [C] Conclusions: According to the scientific evidence and ethic issues surrounding PS, doctors should help couples decide autonomously providing objective information and choosing the most effective and safe methods adapted to each specific case.Downloads
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