Using FISH to increase the yield and accuracy of karyotypes from spontaneous abortion specimens.

Objective: Cytogenetic analysis of spontaneous abortions is frequently complicated by culture failure and maternal cell contamination (MCC). The objective of the study is to demonstrate that multiplex fluorescence in situ hybridization (FISH) can increase the yield and accuracy of karyotypes from spontaneous abortion specimens.

Method: A multiplex interphase FISH probe set was used to analyze two sample sets. (1) Uncultured tissues from 153 abortions samples with a normal 46,XX karyotype and (2) a series of 171 samples that either failed to grow or were contaminated. MCC studies were performed on 70 cultures where both karyotype and FISH indicated a normal female karyotype.

Results: FISH showed 31% (53/171) of the specimens karyotyped as 46,XX were either male or abnormal; 23% (40/118) of these specimens were found to have an abnormal chromosome complement. In specimens with culture failure, FISH showed an abnormal complement in 44.4% (68/153). MCC studies showed 41.49% (29/70) cultures of maternal origin, 45.7% (32/70) fetal, 11.4% (8/70) a maternal/fetal mixture and 1 diploid mole.

Conclusion: Results demonstrate the utility of a simple FISH panel in increasing the detection rate of abnormal karyotypes. They also reveal the high frequency of overgrowth of maternal cells in cultured specimens from villi after embryonic loss.