title: [The importance of ultrasonography in the 1st and 2nd trimester of pregnancy in prenatal diagnosis of chromosome aberrations].
abstract: Indications for examination of the foetal karyotype on the basis of ultrasonic atypies or detection of specific US minor-markers is an important screening method for prenatal detection of chromosomal aneuploidies of the foetus. It is associated with possible detailed evaluation of certain factors by more perfect ultrasonographic equipment. In the group investigated by the authors this indication was of greatest importance for detection of chromosomal aneuploidies in-8.52%. Isada et al. [18] reports 16%; Donner et al. [11] found chromosomal aberrations in 9.5% abnormal sonograms. The highest sensitivity is obtained by assessment of the "nuchal translucency" (NT) which can be investigated during the first and second trimester of pregnancy. In the author's group it was recorded in 47% foetuses with Down's syndrome. Risk assessment of chromosomal trisomies based on the assessed NT during the first trimester was done by means of the Fetal Database programme. The assessment calls for special training. A reduced length of the femur is a significant marker of chromosomal aberrations if the disproportion with BPD between the 15th and 22nd week of gestation is 10 days or more. The importance of other ultrasonographic markers such as a reduced femur, hyperechogenity of the gut, pyelectasia etc. requires further studies. In the author's investigation the risk of chromosomal aberrations increases significantly only after detection of two or more of these atypical features. Chorionic and amniotic atypies in the first trimester and placental dysmorphias (partial moles) in the second trimester of gestation are frequently associated with chromosomal triploidy. The prenatal diagnosis of these abnormalities is possible by the vaginal and transabdominal route. It calls for considerable enlargement of the picture similarly as investigations of "NT".
authors.affiliation: Ustav lékarské genetiky a fetální medicíny FN, Olomouc.
authors.forename: P
authors.initials: P
authors.lastname: Polák
authors.forename: J
authors.initials: J
authors.lastname: Santavý
authors.forename: J
authors.initials: J
authors.lastname: Hyjánek
authors.forename: A
authors.initials: A
authors.lastname: Santavá
authors.forename: P
authors.initials: P
authors.lastname: Capková
mesh_terms: D002869:Chromosome Aberrations / Q000000981:diagnostic imaging*; D025063:Chromosome Disorders; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D016216:Ultrasonography, Prenatal
vernacular_title: Význam ultrazvuku v I. a II. trimestru gravidity pro prenatální diagnostiku chromosomálních aberací.