P052: Can a selective use of amniocentesis replace the routine for advanced maternal age?

To evaluate the amniocentesis may be offered on a selective rather than routine basis in women with advanced maternal age, based upon the results of non-invasive screening test. A series of 296 spontaneous single pregnant women aged 35–40 underwent combined screening test (nuchal translucency -NT- and maternal serum free-beta-hCG, Papp-A), cut-off < 1/250 at term of pregnancy; the women decided to perform amniocentesis upon the results of the test after genetic counseling. The test was positive in 48 women (16.4%), which elected to have an amniocentesis; contrary the all 248 women (83.6%) with negative test refused. All aneuploid fetuses were detected: 6 Down's syndrome (maternal age 37–40), 1 trasl. 13/14 and 1 Turner both with hygroma and maternal age 35; 1 46xx/46XX − 13 serum positive with maternal age 36; 10 cases (3.4%) had an abnormal NT with risk > 1/250 reduced by serum markers. Of the 248 women with low risk, none had a baby with a chromosomal abnormality (95% confidence interval: 0–1.4%). Amniocentesis may be offered to an advanced maternal age population (35 and over 35) selected by the results of the combined test of screening; it is possible reduce the number of amniocentesis by over 80%, while no cases of Down's syndrome (and other chromosomal abnormality) would be missed.