Vasculosyncytial membrane in relation to syncytial knots complicates the placenta in preeclampsia: a histomorphometrical study

Abstract

The vasculosyncytial membrane (VSM), primary site of fetomaternal exchange is formed when syncytiotrophoblast surrounds the terminal villi and make a close contact with capillaries. Some syncytiotrophoblast forms thin single layer of villous and some syncytial nuclei become piled up to form the syncytial knots (SKs). Undoubtedly there is a clear-cut inverse relation between villous VSM and fetal hypoxia. In preeclampsia (PE) the hypoxia injury disrupts the syncytial architecture which in turn initiates other complications of PE. Present study was designed to observe the morphological and histomorphometric features of 84 placentas from control and PE (42 each) collected from Department of Obstetrics and Gynecology. Neonatal weight and placental weight were reduced in PE than the controls but the feto-placental index did not differ. The SK density and VSM thickness was found to be increased and was statistically significant in PE cases. In relation to SKs, the VSM thickness was twofold increased than the controls and was statistically significant. The SKs in the present study were classified as type-1, 2a, 2b, and 3. Type 1 was found to be 62% in control and 47% in PE, type 2a and 2b were 38% in control and 37% in PE, and type 3 was in 8% of PE cases. All the parameters of present study reveal the adverse effects of PE influencing on both morphological and microscopical features of the placenta resulting in fetal hypoxia.

Histology of Placenta in Intrauterine Growth Restricted Pregnancy

“…According to Burton et al (2009) 7 generation of reactive oxygen species under oxidative stress could be the major reason of abnormal vascular remodeling and production of increased syncytial knots. Sankar KD, Bhanu PS, Kiran S et al (2012) 8 in their study reported similar findings with the oxidative stress injury disrupting syncytiotrophoblast arrangement and resulting in increased vasculosyncytial membrane thickness and syncytial knot density.…”

High placental index and poor pregnancy outcomes: a retrospective study of 18 386 pregnancies

“…About pre-eclampsia, one study observed a relative enlargement of the placenta when compared with fetal size [7]. However, a high placental index was not found significantly associated with pre-eclampsia in twin pregnancies [9], and it was neither found significantly associated with pregnancies complicated by pre-eclampsia in a small case control study [8]. This is the first study which clearly demonstrates a significant association between PRHDs and high placental index.…”

“…In pregnancies affected by preeclampsia a relative enlargement of the placenta when compared with fetal size has been seen [7]. However, placental index has been studied in twin pregnancies complicated by pre-eclampsia without finding significant results [8,9]. Furthermore, placental index has been suggested to be useful in studying impaired fetal growth [10].…”

Morphological changes of placental syncytium and their implications for the pathogenesis of preeclampsia

“…Later studies found that the syncytium in preeclamptic placentas was thin and discontinuous with bulbous edges and vacuoles in trophoblasts [16]. Sankar et al reported that the vasculosyncytial membrane thickness, as well as the density and diameter of syncytial knots are significantly increased in preeclamptic placentas [56]. These findings were statistically significant, with a twofold increase in the vasculosyncytial membrane thickness in preeclamptic placentas when compared to normal controls.…”

“…These findings were statistically significant, with a twofold increase in the vasculosyncytial membrane thickness in preeclamptic placentas when compared to normal controls. These structural changes may result in placental functional alterations, contributing to the hypoxic conditions found in preeclampsia [56]. Sodhi et al examined 20 placentas from various grades of preeclampsia and eclampsia patients and 20 placentas from normal pregnancies [57].…”