Placental morphology and clinical correlations in pregnancies complicated by hypertension.

In order to quantify the frequency of placental tissue changes in pregnancies complicated by hypertension and the correlation with the severity of the disease we studied 15 term-placentas of healthy women and 33 placentas of patients with pregnancy hypertension using phase contrast microscopy. Applying microscopy (phase contrast) a total of 50 fields were inspected from 5 different, representative areas of each placenta. We counted the (absolute) number of fields with trophoblastic hyperplasia; trophoblast sprouts; with interstitial edema; with hemorrhagia and with fibrinoid degeneration and necrosis. Trophoblastic hyperplasia as well as interstitial edema were rare in term-placentas of healthy women. Typically in hypertensive pregnancies these findings together with trophoblast sprouts increased proportionally to severity. We conclude that these results indicate a retardation of maturation of placenta tissues in hypertensive pregnancy. Although hemorrhagia and fibrinoid degeneration were observed in all placentas they were more frequent in pregnancies complicated by hypertension. This might be a consequence of changed placental perfusion of the intervillous space. In immature placentas hemorrhagia and fibrinoid degeneration induce additional restriction of placental capacity which seems to be responsible for decreased fetal birth weight and arterial cord pH. When morphological alterations of placenta tissue, e.g. trophoblast sprouts, trophoblast hyperplasia, stroma edema, hemorrhagia and fibrinoid degenerations were quantified and correlated to blood pressure of the mother, we found a positive correlation. Increased numbers of trophoblastic sprouts and trophoblastic hyperplasia indicate a placental immaturity whereas edema, hemorrhagia and degenerations can be taken as the result of elevated blood pressure.