It is also associated with preterm birth and has been isolated from the amniotic fluid, placenta, and chorioamnionic
membranes of women delivering prematurely.
It has become apparent that HEV most often occurs in concert with other placental abnormalities including chronic villitis of unknown etiology, fetal-placental vessel thrombi, villous fibrosis, erythroblastosis, and meconium staining of the chorioamnionic membrane.
Noticeable and/or significant negative associations between case and control groups included acute inflammatory responses of the chorioamnionic membrane and umbilical cord and retroplacental hemorrhage and abruption.
Likewise, meconium staining of the chorioamnionic membrane and chorionic plate may be an indicator of fetal jeopardy, possibly associated with tissue hypoxia.
11-17] We evaluated 10 of these lesions and separated them for the purposes of this study into 2 categories: recent lesions (generally considered to occur within days of the time of labor and delivery), including acute chorioamnionitis, meconium-associated changes, recent chorionic vessel thrombi, changes consistent with abruptio placenta, and increased nucleated red blood cells (NRBC), and chronic lesions (generally believed to have their onset long before labor and delivery), including avascular villi, chronic villitis, perivillous fibrin, changes consistent with maternal vascular underperfusion, and diffuse chorioamnionic hemosiderosis.
Diffuse chorioamnionic hemosiderosis was defined by hemosiderin-laden macrophages in the amnion and chorion of membranes and chorionic plate, plus old blood clot.
These included 4 lesions that were not graded for severity (recent chorionic vessel thrombi, changes consistent with abruptio placenta, diffuse chorioamnionic hemosiderosis, and perivillous fibrin deposition); 4 lesions in which only the most severe variant was more common in cases (meconium-associated vascular necrosis, severe fetal chorioamnionitis, extensive avascular villi, and diffuse chronic villitis); and 1 lesion (increased NRBC) for which both levels of severity were significantly more common in cases, but the odds ratio was higher for the more severe form.
double dagger]) Chronic lesions (generally believed to occur long before labor): extensive avascular villi, diffuse chronic villitis, diffuse chorioamnionic hemosiderosis, and perivillous fibrin.
28,33] Briefly, abruptio placenta and chorioamnionic hemosiderosis (chronic abruption) reflect interruption of maternal perfusion.