[Current indications for invasive prenatal diagnosis. New proposals based on the experience of Institute Nacional de Perinatología].

BACKGROUND: Invasive prenatal diagnosis (IPD) allows identification of fetal diseases, mainly aneuploidy. With the addition of first-trimester prenatal screening and structural ultrasound, IPD indications have changed.

OBJECTIVE: To describe the current indications for IPD in pregnant patients at INPer.

METHODS: Descriptive and retrospective study. We reviewed medical records of patients in which IPD was performed during a period of 2.5 years.

RESULTS: A total of 339 studies were performed: 81% by amniocentesis (AC), 13% by chorionic villus sampling (CVS) and 6% by cordocentesis or somatocentesis. The most common indications for AC were: advanced maternal age (AMA) (43%), fetuses with multiple defects by ultrasonido (23%) and presence of soft markers for aneuploidies (9%). For CVS were: cystic hygroma (24%). Increased nuchal translucency (NT) (24%), and AMA (18%). When the indication was only AMA, 1.5% of fetus presented aneuploidy. In women under 38 years and normal ultrasoud, chromosomal abnormalities were not detected. The increased NT in women <35 years had a 21% detection and in patients > 35 years it increased to 33%.

CONCLUSIONS: We observed that the group who had normal translucencia nucal and AMA presented a low risk of chromosomal abnormalities. In the presence of an increased NT, 33% of fetuses were affected, so that measuring TN is considered the best non invasive PD tool. The average age with cytogenetic abnormalities was above 38 years, so we suggest to offer IPD in women above 38 years-old.