Objectives: To determine the histopathology of failed pregnancy in clinically symptomatic women with no more than one prior pregnancy loss in order to provide baseline data, and to determine whether the histology of the conceptus in spontaneous abortions could predict a normal or abnormal chromosome number.
Methods: A review of all spontaneous abortions from which karyotypes were obtained between 1984-1991 yielded 224 cases in which maternal history indicated no more than one prior spontaneous abortion, a reliable date of last menstrual period (LMP), and available villous (221) and/or decidual/implantation site (175) pathology. Molar pregnancies were excluded.
Results: Multivariate logistic regression analysis showed a significant relationship between chromosome number and gestational age at loss as calculated from the LMP. Considering this confounder, a villous circulation indicating fetal life to 11 or more weeks, chronic intervillositis and villous infarcts (each P < .01), and decidual vasculitis (P < .05) were more frequent in chromosomally normal conceptions. Substituting possible variables into the logistic regression equation yielded predictions ranging from 88% likelihood of chromosomal abnormality to 97% likelihood of normal chromosome number.
Conclusions: Histology can assist in assessing whether a spontaneous abortion is chromosomally normal or abnormal. There are many pathologic findings seen in spontaneous abortions regardless of karyotype; however, certain findings are more common in chromosomally normal abortions. These data provide a baseline for study of the histopathology of habitual abortion.