ABNORMAL EMBRYOGENESIS IN THE ETIOLOGY OF ECTOPIC PREGNANCY

Flow cytometric measurements of DNA using paraffin-embedded retrospect ive material were performed on 42 samples of ectopic conceptuses to se e whether there were any aberrations from normal DNA. It was found tha t DNA aneuploidy was associated with tubal implantation in 14 (33%) ca ses. The range of DNA indices of the DNA aneuploid peaks was from 1.14 to 2.17. Near-diploid karyotype changes were seen in 8 (19%) cases. S ix cases were found to be tetraploid. In 18 abortions with known cytog enetic status, all 3 cytogenetically normal cases showed DNA diploidy in flow cytometry. It was also found that 3 out of 10 cases of trisomy 21 were DNA aneuploid. Flow cytometric DNA reflects only chromosomal changes where a significant number of cells have either lost or acquir ed several chromosomes. DNA aneuploidy of ectopic pregnancies suggests a grave chromosomal aberration in one third of the cases. Abnormal em bryogenesis may contribute significantly to the occurrence of ectopic implantation.