No abstract

Objective: A new method in prenatal diagnostics allows to demonstrate certain numeric chromosomal aneuploidies in amniotic cells within 24 h in contrast to conventional methods which take 1–3 weeks. Materials: The experience with this rapid fluorescence in situ hybridization (FISH) method is compared to standard karyotyping and its clinical relevance is described in a large clinical pilot study. FISH on uncultured amniocytes has been performed from 12 weeks of gestation to the third trimester using commercially available chromosome-specific DNA probes for chromosomes 13, 18, 21, X and Y. Results: FISH was performed successfully in 3,150 prenatal cases. All trisomies 13, 18 and 21 and all cases with gonosomal aberrations were detected by FISH analysis. Neither false-positive nor false-negative results were obtained using FISH. For all analyzable disorders the FISH results were in complete agreement with standard cytogenetics. Conclusions: In our experience, FISH is a valuable and reliable method for rapid diagnosis of numeric chromosomal aneuploidies.

Trisomy 13 is very rare in live-born children. Only a small number of these children survive the first year and very few cases are reported to live longer. Survival time depends partly on the cytogenetic findings--full trisomy 13 or trisomy 13 mosaicism--and partly on the existence of serious somatic malformations. We report on a 11-year-old girl with full trisomy 13. In this case, missing cerebral and cardiovascular malformations probably allowed the long survival.

In Germany, Austria and Switzerland the results of screening for chromosomal defects by measurement of fetal nuchal translucency thickness, in centers with appropriately qualified sonographers and using The Fetal Medicine Foundation's software, are similar to those reported in the UK using the same methodology.

To evaluate the risk of abortion after genetic amniocentesis in twin pregnancies, a retrospective study of 15 centers was performed. The spontaneous abortion rate up to 20 completed weeks of gestation was 2.3%; the abortion rate up to 28 completed weeks, as defined by WHO, was 3.7%. The abortion rate could not be correlated either with the number of needle insertions or with the type of marker dye used. There was also no correlation between the abortion rate and the gestational age at which amniocentesis was performed. A significant association was shown between congenital intestinal obstructions and the application of methylene blue intra-amniotically as a marker dye. Considering the increased natural loss rate in multiple gestations, amniocentesis in twin pregnancies seems to be a safe and reliable technique.