Background: In perinatal settings, fluorescence in situ hybridization has the potential to provide specific chromosome evaluation when full karyotype analysis is not possible because there are no dividing cells.
Case: Based on clinical features, cases of fetal and neonatal demise were selected for evaluation with chromosome-specific probes. Sources of nondividing cells included deparaffinated tissue sections, disaggregated tissue biopsies, and archived, Giemsa-stained slides.
Conclusion: Diagnostic information was obtained by fluorescence in situ hybridization in three settings: 1) postmortem trisomy 21 identification from paraffin sections following unsuccessful tissue culture, 2) postmortem trisomy 18 confirmation in disaggregated cells from macerated fetal tissues, and 3) retrospective documentation of a cryptic deletion (22q-) in archived metaphase spreads. We encourage familiarity by obstetricians with fluorescence in situ hybridization for chromosomal assessment using archived fetal material.