Rapid confirmation of previously detected prenatal mosaicism by fluorescence in situ hybridization in interphase uncultured amniocytes

Fluorescence in situ hybridization (FISH) of chromosome-specific probes to interphase uncultured amniocytes was performed in cases in which follow-up amniocenteses were done for confirmation of previously detected mosaicism. FISH results were informative in all seven cases included in the study, and confirmed by subsequent cytogenetic analysis. FISH analysis provides rapid results for referral physicians and in most cases reassurance for patients within 24 hours of the follow-up aminocentesis. Although FISH studies are not considered accurate in determining a primary diagnosis of mosaicism in uncultured cells, the analysis is accurate and clinically useful when the diagnosis is known and mosaicism involving a specific chromosome needs to be confirmed in follow-up testing.