Histopathological Alterations in Fetal Membranes of Women With Endometriosis

Abstract

Previously, we reported endometriotic-like decidual lesions in contact with the fetal membranes (FMs) in 11 pregnant women with severe endometriosis. In this report, an extensive histomorphological analysis was performed on the FMs of 19 pregnant women with deep infiltrating endometriosis (DIE) at term pregnancy and who delivered by cesarean delivery before labor. On gross examination, all samples showed increased thickness, de novo microvessel formation, and small-size excrescences distributed along the membrane circumference. Histological examination of FM fragments sampled from the placenta edges or from the cesarean incision line showed fibrinoid necrosis and connective tissue accumulation in the amnion, chorion, and decidual layers in most of the 19 women with DIE. Papillary tufting and epithelial cell multilayering at the surface of the amnion layer were found in 3 of the 19 women with DIE. In 14 of the 19 women with DIE, the trophoblastic layer was disrupted by dense extracellular material, degenerative villi, and inflammatory infiltrates. Cystic gland-like structures were found in the decidual layer in all the 19 women with DIE, which were surrounded by irradiating small vessels and scattered inflammatory cells. The relationship between these peculiar histological changes and the endometriotic status of the pregnant women is still unclear. Sustained examination of FMs in women with DIE is needed to fully evaluate the defaults in these tissue structures and to establish whether these defaults have clinical impact on the pregnancy course.