Rapid prenatal diagnostics in the interphase nucleus: procedure and cut-off rates.

Results of a rapid prenatal aneuploidy screening in uncultured amniocytes using FISH are available within 24 hr. However, care has to be taken of possible pitfalls in connection with the commercially available probe sets and in the interpretation of results in general. Here we present our cut-off rates for and the way in which we handle the Aneu Vysion kit (ABBOTT/Vysis), based on the experience of 1200 studied cases. In summary, the method is reliable, and the risk for misdiagnosis is low ( approximately 0.4%). Nonetheless, the test should be used exclusively as a preamble to full chromosome analysis by microscopy.