Here, the first evaluation is presented of the
first-trimester combined test screening carried out in the Netherlands among
pregnant women to determine the chance of the baby being born with Down's
syndrome. The screening, commissioned by the Health Care Inspectorate of
the Dutch Ministry of Health, Welfare and Sport, took place in a
multi-centre routine clinical setting between July 2002 and May 2004. In
this period blood samples were taken in 44 centres in the Netherlands and
sent to the RIVM laboratory to perform assays for maternal serum
concentrations of fB-hCG and PAPP-A. Fetal nuchal translucency was measured
in the participating centres at a gestational age (GA) of 10-14 weeks.
Almost 7800 blood serum tests were performed. There was an impressive
increase in the number of women applying for the test (from 341 per 6 months
in the second half of 2002 to 11,046 per 6 months in the second half of
2005). The distribution of GA was biphasic, with a median GA of 10.3 and
12.1 weeks. Results of pregnancies for which a combined biochemical and
nuchal translucency risk was calculated, were included in the
epidemiological analysis. Here, the detection rate using the combined
ultrasound and serum screening at a cut-off level of 1 in 250 was 71% (15 of
the 21 Down's syndrome cases detected) with a screen positive rate of 4.7
%. The median maternal age of the analysed group (including 4033 singleton
pregnancies) was 36.5 years. The outcome of the pregnancy was reported to
the RIVM for 82% of all the applications of the first-trimester combination
test screening in the July 2002 to May 2004 period. Results also show that
the first-trimester combined test is suitable as a prenatal screening test
in a multicentre routine clinical setting in the Netherlands. Strict
performance evaluation should identify weaknesses in the organisation that
impair the performance of the test. Here, especially the performance of the
NT was identified as a candidate for improvement.
