[Sonographic detection of fetal epiphyseal centers--an additional parameter for determining delivery date].

A new ultrasonic method based on X-ray concepts for depicting prenatally developed centers in the tarsal bones, calcaneus and talus, as well as and especially in the epiphysis centers of the fetal knee joint is described. Investigations of average collectives show that the center in the calcaneus becomes visible during the 24th week of pregnancy, on the average, whereas the center in the talus becomes visible during the 26th week after begin of amenorrhea. The growth charts of both these tarsal centers demonstrate almost linear growth until parturition, the very slight increase per week, however, limits the possibilities for their use in determining the period of gestation. The epiphysis center in the distal femur becomes visible by ultrasonic methods during the 32nd week of pregnancy, on the average, the center in the proximal tibia appears later, during the 37th week after amenorrhea begins. Both epiphysis centers show an almost linear increase in size from the time they first appear; the center in the femur, however, has a growth chart that shows levelling off after the 38th week of pregnancy. The differences between X-ray and ultrasonic representation, which become evident upon comparing growth charts as well as in a separate and direct comparison are shown to be due, through the results of a parallel histological study, to an increase in density of the cartilage matrix prior to ossification. Of the fetal factors which were investigated only the weight and length of the child show a slight, and for practical purposes negligable influence on the size of the epiphysis centers, whereby only the results showing that the femur centers tend to be larger when the child is heavier and longer appear significant. Neither sex nor maternal factors influence the size of the visible epiphysis centers in any way. A slight modification in the case of diabetics and pregnancy induced hypertension patients seems to most likely be due to the macrosomal and retarded children occurring in these groups. None of the factors investigated effect a significant difference in the ultrasonic development or time of appearance of the epiphysis centers. In view of the fact that growth charts show levelling off and of the wider biological scattering range of all parameters currently used to determine the duration of gestation during the last trimenon, making use of this new ultrasonic method with its double advantage - the first appearance of the centers during the last quarter of pregnancy as well as the following near-linear increase in size - seems to suggest itself.(ABSTRACT TRUNCATED AT 400 WORDS)