[Ultrastructural examination of the placenta in pregnancy complicated by diabetes mellitus].

Background: Causes of fetal hypoxia in diabetic pregnancy are still unknown. Investigation of placental vascular network seems of great importance in this research area. Abnormalities in the structure of capillaries in the vasculo-epithelial membranes and role of perivascular space may be an essential factor in explanation for fetal hypoxia in diabetic pregnant women. The aim of the study was to evaluate the relationship between the vascular surface of the terminal villi to its total surface, evaluation of the endothelial structure, perivascular space and basal membrane of the trophoblast as well as analysis of the studied parameters in relation to the classes of diabetes and metabolic control.
Material and Methods: The study was performed on 32 placentas from women with PGDM and GDM. There were 8 pregnant women in class G1 and G2, 15 in class B, C, D, 9 in class R/F and 8 in control group. The mean diurnal glycemia in the analysed groups ranged between 90 + 22 mg/dl and 100 + 55 mg/dl (in control group 80 + 12 mg/dl). HbA1c concentrations were between 6.7 + 0.9% and 7.6 + 1.0% (in control group 6.0 + 0.5%). Placentas were examined using light microscopy and electron microscopy Opton-Zeiss EM-900.
Results: Decrease in the vascular surface of terminal villi was found in PGDM with fetal hypotrophy. In this cases we observed separation of basal membranes in basal capillaries and distention and proliferation of endothelial cells, disarrangements of perivascular space,. In placentas of women with hyperglycemia and fetal macrosomia there was a significant thickening of basal membranes of the trophoblast, and structural abnormalities in perivascular space with proliferation of collagen in terminal villi. Intensity of these changes was related to the degree of hyperglycemia and affected fetal and neonatal wellbeing. Examination of the placentas in women with PGDM with normal sugar levels before and during pregnancy revealed no or very limited pathological changes on light and electron microscopy. No significant relationships were shown between vascular surface in terminal villi and selected biochemical parameters and neonatal condition in diabetic pregnant women with fetal eutrophy
Conclusions: Pathologic changes in the placentas of diabetic women (significant thickening of basal membranes of trophoblast separation of basal membranes in basal capillaries, distention and proliferation of endothelial cells, disarrangements of perivascular space and decrease of vascular surface of terminal villi are significant factors contributing to fetal anoxia in pregnancy complicated by diabetes mellitus.