A morphometric approach to the relation of karyotype, gestational age and histological features in early spontaneous abortions.

Previous studies revealed that chorionic villus size and proliferation of trophoblast were of little value as predictors of chromosomal abnormality. Since these findings might be due to the known intra- and inter-observer variation in histological assessments of early placentae, objective measurement of features might be more valuable to predict abnormal karyotype. Also, gestational age might influence structural development of villi in different karyotypes in a variable way, obscuring a possible relationship between features and karyotype. We, therefore, quantified villus size composed of stromal and trophoblastic tissues in 82 placentae using the point counting method and related the results to karyotype and gestational age. At the group level there appeared to be no difference in the median mean cross-sectional villus-, stromal and trophoblastic area, trophoblast/stroma ratio and trophoblastic thickness between chromosomally normal and abnormal placentae. Of the abnormal placentae only triploid placentae showed areas larger than normal and other abnormal placentae. In respect of gestational age villous profile area increased with age in triploid placentae, but decreased in trisomic abortions. At the individual case level parameter values outside the 'normal' range appeared to be rather insensitive, but highly specific for the prediction of karyotypic aberrations, again mainly triploidy.