Impact of First-Trimester Aneuploidy Screening in a High-Risk Population

Abstract

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 ≥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 χ² 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.

Indications for Fetal Invasive Procedures at the End of an Era

“…This will hamper a further increase in overall uptake of combined first trimester screening [13]. These above-mentioned regulations may also be responsible for the high proportion of invasive procedures (27 %) performed in our cohort due to advanced maternal age > 35 years (▶ Table 2) compared to 14 -15 % in the literature [8,14]. According to a Dutch study [9], 70 % of all women > 35 years will still be referred for invasive prenatal diagnosis.…”