No abstract

Fifty-three pairs of twins were obtained during examination of 1,939 spontaneously aborted complete embryos and fetuses. Therefore, the rate of twinning in pregnancies which spontaneously aborted was about 1 in 35. The spontaneous twin abortions consisted of 25 sets of twin embryos, 26 sets of twin fetuses, and two sets in which one was an embryo and one was a fetus. It was possible to determine the zygosity in 37 pairs. The ratio of monozygotic to dizygotic was 17.5:1. About 88% of the twin embryos and 21% of the twin fetuses were abnormal. These abnormality rates were similar to those observed in the overall study of the abortuses. The data on spontaneously aborted twins were compared with data on liveborn twins. The results suggest that twinning, particularly MZ twinning, occurs more frequently than has been thought, based on newborn data, and that embryonic and fetal mortality is much higher in twins than in singletons.

A systematic gross and microscopic study of the placenta was done on human spontaneous abortions, correlating placental morphology and karyotype of the conceptus. Consistent abnormalities were seen in the four major forms of human heteroploidy, so that a fairly accurate ""karyotypic diagnosis'' could be made from careful gross and microscopic examination of the aborted material. Depressed growth activity and dysmorphogenesis characterized these placentas, reflecting placental participation in the disturbed phenotypic expression of heteroploidy.

Using high-resolution real-time ultrasound in the first trimester of pregnancy, we have been able to demonstrate, in addition to the fetus, the yolk sac and the amniotic membrane. Pitfalls to avoid in first-trimester pregnancies include (a) mistaking the yolk sac for a second separate fetus, (b) including the yolk sac in the crown-rump length, and (c) misinterpreting the amniotic membrane for a septum between two separate gestational sacs.

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Ectopic pregnancy in the fallopian tube occurs in about 1 in 50 human pregnancies. Maternal factors in the etiology of this condition have been well documented. There is less information available on the development of the embryo or fetus. To document this information morphological and cytogenetic data were obtained from 76 embryos and fetuses obtained from pregnancies occurring in the fallopian tube. Analysis of the data showed that tubal implantation was associated with a high proportion of severely disorganized embryos. There was also a high incidence of maternal tubal disease. The importance of these factors and the etiology of ectopic pregnancy is discussed.

henty-two fetuses with bilateral hygromata, lymphedema, and other associated anomalies are described. ' h o fetuses had a 45,X karyotype, five were sex chromatin-negative. The association of specific external and internal anomalies is suggestive of the phenotype of Turner syndrome and a 45,X karyotype .

Molar diseases of the placenta is associated with cystic change in the villi. The cysts may be from 5-20+ mm in diameter. This disease has been described in association with triploid and diploid cell lines and with and without an accompanying embryo or fetus. It may be followed by malignant change and invasive chorio-carcinoma. In order to investigate the association between cell ploidy, embryonic development and subsequent malignancy, a detailed study of 30 conceptuses with molar disease was made, with the accompanying maternal history and follow-up. The cell ploidy was determined by measurement of nuclei by a cytoscan light microscope connected to a computer program as has been previously described. Diploid cell lines were not found with embryonic or fetal development. Triploid cell lines were always associated with an embryo or fetus. Triploidy is not associated with hyperplastic changes in the trophoblast. These results are presented and discussed.