Prevalence and distribution of chromosome abnormalities in a sample of first trimester internal abortions

Abstract

Cytogenetic analysis was performed directly on villus from 202 samples obtained at the evacuation of tbe uterine cavity in cases of retained abortion in the first trimester, identified as such by ultrasound enamination. A precise delineation of tbe karyotype was obtained in 94% of the cases, while the efficiency of karyotype analysis in samples of spontaneous abortion was not higher than 50%. An abnormal chromosome constitution was found in 145 fetuses (76.7%) of which 117, including mosaics, were aneuploid (70%), 16 polyploid (8.5%) and l2 had structural abnormalities (6.3%). The relative proportion of chromosome abnormalities in this material is higher than that found in spontaneous abortion for trisomies and double trisomies, but lower for 45,X and polyploidy. The method was found to be efficient in obtaining fetal karyotypes also in those cases in which the villous material was scarce (1 mg), and thus it seems appropriate for routine cytogenetic studies in the first trimester abortions.