Cribado combinado para la detección de trisomía 21 en el primer trimestre de la gestación. Impacto sobre la tasa de procedimientos invasivos de diagnóstico prenatal tras 5 años de implementación

Objective

To assess the effectiveness of first-trimester combined screening in the prenatal detection of Down syndrome after 5 years of use in our hospital and its impact in reducing invasive diagnostic tests.

Material and methods

The risk of fetal chromosomal anomalies was assessed in 10,669 pregnancies with first-trimester combined screening between May 2006 and December 2010. The cut-off to indicate an invasive diagnostic test was 1/270. The amniocenteses performed between 2005 and 2010 were also analyzed.

Results

The detection rate of screening for trisomy 21 was 90% and the false-positive rate was 3.56%. In pregnant women aged 35 years or more, the detection rate was 96.7%. In 2005 there were 496 amniocenteses. In 2010, 5 years after the introduction of screening, 148 amniocenteses were performed, representing a 70% reduction in invasive procedures.

Conclusions

The introduction of combined screening in our environment has proven effective for the detection of trisomy 21 and has substantially reduced the use of invasive prenatal diagnostic procedures. The use of advanced maternal age as an isolated criterion to indicate invasive techniques to study fetal karyotype should be questioned if high-quality universal screening is to be offered.