Impact of first-trimester aneuploidy screening in a high-risk population.

OBJECTIVE: To determine the impact on maternal decision-making of offering first-trimester screening to women at increased risk for fetal aneuploidy. METHODS: A retrospective chart review of all patients > or = 35 years of age at delivery who registered to deliver at Massachusetts General Hospital before (2000-2002; n = 1,604) and after (2003-2005; n = 1,915) the introduction of first-trimester screening. Demographics, the choice of screening test and/or invasive procedure (chorionic villus sampling or amniocentesis), and the detection rate of fetal aneuploidy were compared between the two groups by chi(2) test. Aneuploid newborns without an antenatal diagnosis were reviewed in detail. RESULTS: The fraction of women who accepted prenatal screening and/or an invasive procedure increased from 1,122/1,604 (70%) to 1,751/1,915 (91%, p < 0.01) after the introduction of first-trimester screening. Fewer invasive procedures were done in the second time period, due to a decrease from 40 to 14% in the fraction of women going straight to an invasive procedure without screening (p < 0.01). Similar numbers of aneuploid fetuses were detected prenatally in the two time periods: 21/22 (95%) in the first time period and 22/25 (88%) in the second (p = 0.36). All 4 cases not prenatally diagnosed involved the patient's decision to decline screening or ignore positive screening results. CONCLUSION: The introduction of first-trimester screening in a high-risk population was associated with an increase in the acceptance of prenatal screening and a reduction in the invasive procedure rate without a concomitant decrease in the detection of fetal aneuploidy.

Low or absent unconjugated estriol in pregnancy: an indicator for steroid sulfatase deficiency detectable by fluorescence in situ hybridization and biochemical analysis.

It has been previously reported that a low or absent maternal serum unconjugated estriol (uE3) level is associated with placental steroid sulfatase (STS) deficiency. Here we report a correlation between patients who present with a very low or absent maternal serum uE3 and a deletion of the STS gene as assessed by fluorescence in situ hybridization (FISH). We studied nine prenatal cases that presented to the clinical laboratory with an abnormal triple screen, specifically low or absent maternal serum uE3 and a 46,XY karyotype. FISH analysis showed complete deletion of a probe containing the STS gene in six cases and one case had a partial deletion (reduced but not absent signal). The remaining two cases were not deleted for the STS probe. All mothers tested whose fetus showed a deletion were shown to be STS deletion carriers using FISH. Biochemical analysis was performed on 7/9 prenatal specimens. All fetuses deleted for the STS probe were also found to be deficient for STS by biochemical analysis of cultured amniotic fluid (5/5). Of the two fetuses not deleted for the STS probe, one was deficient for STS activity, while the other had a normal result. The abnormal result of enzyme deficiency by biochemical analysis in a non-deletion case likely represents a mutation in the STS gene, not detectable by this FISH assay. Postnatal FISH confirmation of the STS deletion was performed in 1/7 cases. Clinical follow-up was available for 4/9 cases following birth.