Intra- and inter-observer variation in the interpretation of histological features suggesting chromosomal abnormality in early abortion specimens.

Early spontaneous abortion is a common phenomenon, with more than 50% of early cases showing chromosomal abnormalities. We have undertaken a study to evaluate intra- and inter-observer reproducibility of histological diagnoses of features associated with chromosomal abnormalities, such as chorionic villus size, shape, vascularity, trophoblastic proliferation and trophoblastic pseudo-inclusions. The intra-observer variation for most histological features was small. However, the agreement beyond chance between two or more observers in judging histomorphological features of early abortion placentae only reached clinically relevant values for size and shape of the chorionic villi and for the number of trophoblastic pseudo-inclusions.