Objective: To investigate the invason of trophoblasts in the placenta bed and the change of spiral arteries and microvessels in pre-eclampsia and normal pregnancy.
Methods: Twenty cases of normal pregnancies, mild pre-eclampsia and severe pre-eclampsia were chosen as Group A, Group B, and Group C. HE staining and immunohistochemistry staining (SP method) were used to observe the depth and the density of trophoblasts invading the placenta bed and the change of spiral arteries and microvessels.
Results: The significant difference in the degree of invasion was in the superficial myometrial segment. Group C was the most superficial in the 3 groups (P<0.01). The density of trophoblasts which invaded the placenta bed in the lower half of the basal decidual segment and the myometrial segment showed us Group C was the lowest (P<0.01). There was statistical difference among the 3 groups (P<0.01). The average lumen area of the spiral arteries in the decidual segment and the superficial myometrial segment of the placenta bed was the smallest in Group C among the 3 groups(P<0.01) and there was statistical difference among the 3 groups (P<0.01). The spiral arteries were the thickest in Group C with statistical difference among the 3 groups (P<0.01). The physiological and pathological change of the spiral arteries was mainly in the superficial myometrial segment. The incidence rate of physiological changes in the spiral arteries was the lowest in Group C with statistical difference among the 3 groups (P<0.01). The incidence rate of pathological changes was the highest in Group C (P<0.01) and the normal group was the highest. There was significant difference among the 3 groups(P<0.01). There was positive correlation between the physiological change of the spiral arteries and the invaing degree of the trophoblasts (P<0.05), there was negative correlation between the pathological change of the spiral arteries and the invasion depth as well as the invasion density of the trophoblasts(P<0.05). There was negative correlation between the physiological change and the pathogenetic condition of pre-eclampsia(P<0.05)while there was positive correlation between the pathological change and the pathogenetic condition degree of pre-eclampsia(P<0.05). There was negative correlation between the invasion depth as well as density in uteruso superficial myometrial segment by trophoblast and the pathogenetic condition degree of pre-eclampsia(P<0.05). There was invasion trophoblast in 62.50% lumen wall of spiral arteries in uterus superficial myometrial segment of the placental bed in normal pregnancy while 27.5% was seen in severe pre-eclampsia. Microvascular density in the decidual segment and the superficial myometrial segment of the placenta bed in Group C was the lowest among the 3 groups with statistical difference (P<0.01).
Conclusion: The invasion depth of the trophoblasts in pre-eclampsia was more superficial than normal pregnancy.The changes of the invasion of the trophoblasts and the pathological changes of the spiral arteries in the placenta bed mainly existed in the superficial myometrial segment which was closely related to the severity of the illness. That microvascular density in the placental bed of pre-eclampsia started to decrease from the basal decidual segment shows that the microvessel development in the placenta bed is impaired in pre-eclampsia.