[Echographic markers of chromosome abnormalities]

Many recent studies have identified biometric parameters which can be used as screening factors in the diagnosis of chromosomic anomalies. This derives from the assertion that karyotype testing in over-35-year-old women alone only allows 20-30% of fetuses suffering from chromosomic anomalies to be diagnosed. The majority of these fetuses remain undiagnosed during the prenatal period given that a high percentage of younger women are excluded from screening. For a long time researchers have hoped to introduce the assay of clinical and instrumental parameters thus allowing anomalous fetuses to be diagnosed in under-35-year-old women. It is now possible to define a biochemical parameter in maternal sera which can identify women at risk and refer them for cytogenetic tests: AFP assay and still more recently the contemporary assay of AFP, estriol and beta-HCG allows greater diagnostic accuracy. However, even using this method only part of those fetuses with chromosomic alterations are identified. Since it is unlikely that screening could be performed without indications in the under 35-year-old age group, it is important to identify routine echographic parameters which can then serve as the indication for subsequent cytogenetic tests and a definitive diagnosis. In this way, by integrating ultrasonographic examination, using biometric and morphological tests, with a biochemical evaluation it will be possible to achieve a higher percentage of diagnosis. This paper examines the most common malformations including trisomy 13, trisomy 18 and trisomy 21 syndromes, Turner's syndrome and triploidy, together with the main echographic findings which accompany them.