FETAL THROMBOTIC VASCULOPATHY - THE CLINICAL-SIGNIFICANCE OF EXTENSIVE AVASCULAR-VILLI

Thrombosis of large fetal vessels in the placenta leads to regions of downstream avascular villi (AV). Avascular villi have been associated with adverse outcomes in anecdotal reports, but no controlled study of their significance has been done. We prospectively gathered cases of extensive AV (n=29) occurring over a 2-year period at the Institute of Pathology at Case Western Reserve University and compared obstetric h istory, coexistent placental pathology, and neonatal outcome to gestat ional age-matched controls in a case control study. The diagnosis of e xtensive AV required one or more of the following characteristics: 2.5 % or more of total villous parenchyma affected, fod in multiple sectio ns, or a single lesion measuring 0.25 cm(2) or larger. Women with AV p lacentas had increased rates of intrauterine growth retardation (IUGR) , acute and chronic monitoring abnormalities, oligohydramnios, and mat ernal coagulation disorders. Placentas with AV were more likely to hav e coexistent chronic villitis, membrane hemosiderin, meconium in all t hree membrane layers, and villous chorangiosis. Finally, among the sub group of neonates older than 34 weeks gestation without congenital mal formations or coexistent placental pathology (n=18), we identified sig nificant abnormalities, including major thrombotic events (n=5), neona tal death (n=2), umbilical artery pH less than 7.10 (n=4), platelet co unt less than 150,000 (n=4), increased nucleated red blood cell (NRBC) counts (n=7), and transient hyploglycemia (n=4). Placental features c orrelating with clinical abnormalities included percentage of greater than 30% AV, recent platelet and fibrin aggregates, and multifocal dis ease involving more than one histological section. HUM PATHOL 26:80-85 . Copyright (C) 1995 by W.B. Saunders Company