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.