Placentationsstörungen

Re-view and view on maturation disorders in the placenta

Until delivery, the placenta plays an important mediator role between mother and fetus. This unit is affected by peristatic conditions, such as acute or chronic maternal diseases, malnutrition, drugs, and others. But also genetic factors and fetal malformations due to embryonic developmental disorders may contribute to macroscopically visible changes and functional disorders of the placenta. In a constantly ongoing progress of maturation, the placenta records and saves changes due to fetal distress partly as maturation disorders. Understanding of maturation disorders might, therefore, be an important contribution to a better understanding of influences on villous differentiation and might improve follow up and fetal outcome to reduce recurrence risk. However, an internationally unified classification system of maturation disorders does not exist. In this review, terminology, trials, and classifications of villous maturation disorders are summed up and compared, to pinpoint the need of agreement on an international unified and reproducible classification of maturation disorders.

Morphology of placental villi after premature delivery and its clinical relevance

Based on a new concept of maturation of the placental villous tree and its disorders (synchronous and asynchronous immaturity, asynchronous maturity, hypermaturity, and terminal villi deficiency) we studied the possible effect of the placental villous tree on the premature onset of labour. In mature normal neonates irregular and asynchronous villous patterns were found in 50% of cases. In prematurely delivered neonates, only 33% of the corresponding placentas show synchronous immature villous patterns. Uterine bleeding in the first trimester was associated with a 42% of incidence of premature maturation of the villous tree. These findings strengthen the idea that hormonal imbalance in early pregnancy influenced villous development. In "prematurity without recognizable cause" there was a higher percentage of villous maldevelopment (33%) than that previously described in the literature. In severe pre-eclampsia combined with premature onset of labour, 60% of our cases showed hypermaturity of the villous trees. Synchronous immaturity was reduced to 15%. We conclude, that even a rather rough definition of the histological features of placental villi is sufficient to produce numerous correlations between clinical events preceding premature delivery and placental structure. So the influence of placenta on the premature onset of labour needs more attention.

A study of placental villi in extrauterine gestation: a guide to the frequency of blighted ova

Material from 329 tubal pregnancies has been examined histologically. In addition, the villous content of glucosaminoglycans was studied. Depending on the degree of the morphological changes three groups can be differentiated: "abortion in association with normal placental findings", "suspicion of blighted ova", and "blighted ova". In the first group (35 cases, 10.64 per cent) there were distinct differences in the morphological picture in contrast to the normal abortion of intrauterine origin; that is, differing size of chorionic villi, the presence of isolated molar villi and proliferative changes in the epithelium. A normal morphological villous pattern was extremely rare. The second group (146 cases, 44.41 per cent) showed all the morphological signs of transition to blighted ova. Most villi were well-vascularized but there were more molar villi, and proliferative and degenerative changes were seen in the epithelium. Group three (132 cases, 40.19 per cent) showed the full picture of a blighted ova. The morphological pattern of the extrauterine blighted ova was similar to that seen in the blighted ova of intrauterine origin, the only difference being that the vascularization of the villi was more pronounced in blighted ova of tubal pregnancies. Glucosaminoglycans were non-uniformly distributed over the villous stroma in the case of blighted ova, and they were present in greater concentration than in the case of abortions with normal placental findings: this is a useful method for differentiating abortions from blighted ova. It is apparent from the results of this investigation that the proportion of blighted ova is substantially greater in extrauterine than in intrauterine pregnancies. This suggests that unfavourable conditions of nidation within the tube have a decisive influence upon the genesis of blighted ova. Furthermore, the unfavourable environment appears adversely to influence trophoblastic development.