Trisomy 18 and Trisomy 13 Prenatal Screening & Diagnosis
Prenatal diagnosis of a fetus with a trisomy condition generally results in a discussion with the obstetrician about termination or continuation of the pregnancy. Genetic counseling is recommended for those with a positive diagnosis. Perinatal palliative care is available in most areas for expectant mothers who choose to continue a pregnancy with a life-limiting diagnosis. Some mothers report being pressured to terminate when diagnosed or encouraged to provide only comfort care for the live born infant. Some parents decline prenatal testing for personal reasons.
Traditional prenatal screening includes follow-up confirmation by invasive tests (e.g. chorionic villus sampling (CVS) or amniocentesis). Invasive tests have a less than 1% risk for the fetus. An explanation of traditional prenatal screening can be found here.
The recent development and marketing of a non-invasive prenatal diagnostic test (NIPD) uses DNA testing with a single blood draw from the mother. See a discussion about this new technology by Dr John C. Carey: http://trisomy.org/professional-viewpoint/