The placentas of patients with severe acute respiratory syndrome: a pathophysiological evaluation

Ng, W. F.; Wong, S. F.; Lam, A.; Mak, Y. F.; Yao, H.; Lee, K. C.; Chow, K. M.; Yu, W. C.; Ho, L. C.

Summary Aims The pathology of the placentas delivered from pregnant women who had severe acute respiratory syndrome (SARS) in Hong Kong was studied. Methods The pathology of the placentas was retrospectively studied in detail and compared with control sets. The clinical data of the women and neonates were also reviewed. Results A total of seven placentas were studied. The placentas from two women convalescent from SARS in the first trimester were normal. In three placentas delivered in the acute stage of SARS, there were increases in intervillous or subchorionic fibrin which might be related to disturbances in maternal placental blood flow due to the hypoxic respiratory disease. Extensive fetal thrombotic vasculopathy (FTV) with sharply demarcated zones of avascular fibrotic villi was noted in the placentas of two patients convalescent from SARS in the third trimester. Both pregnancies had intrauterine growth retardation, oligohydramnios and newborns small for gestation. The aetiology of the FTV might be related to thrombotic tendency due to SARS or placental hypoxia. Conclusions This report highlights placental pathology that was probably the result of pathophysiological alteration of the maternal fetal unit during SARS. Further studies are required to delineate the relationship between severe maternal respiratory disease, placental pathology and pregnancy outcome.