Ever since Papanicolaou (1923, 1933) first reported the application of vaginal smears in determining the changes in pregnancy, cytological studies on the vaginal smears in the field of obstetrics gained its importance in the application for early diagnosis of pregnancy, for various disturbances and fidings during pregnancy, for the prognosis, for the determination of fetal sex, and for the determination of the delivery time. In this field of study there are numerous works, but reports of the successive follow-up studies on the same subject are scarce and for in between. In view of individual differences in the cytological picture of vaginal smears and various changes under varied conditions it is impossible to carry on accurate observations satisfactorily unless continuous observations be carried on the same subject. Therefore, the author undertook a series of continuous observations as regards changes in vaginal smears in the course of pregnancy from the endocrinological standpoint and studied the diagnostic value of the vaginal smears on the determination of the delivery time and various disturbances, and conducted screening tests for the purpose of detecting uterine cancers as well.
The subjects of the present research were 1, 275 patients visiting our obstetrics clinic during the period from July 1, 1957 to the end of December 1958. Vaginal smears were taken from everyone of them, and after staining these smears with Papanicolaou E. A. 36 stain observations were carried on. As for the endocrinological observations the author stupied the percentage of various cells, variations in the cornification index and acidophilic index, charactristics of various cells, and components other than those of the epithelium. The representation of the determined values are classified into I to V grades according to Papanicolaou's method.
The Experimental Results 1. In the continuous observations carried on the changes in the vaginal smears of 40 normally pregnant women for the period from the early stage of pregnancy to the stage just before delivery distinct differences can be recognized according to the degree of cleanliness. Namely, in 21 cases whose cleanliness has been maintained at a high degree throughout the period a considerable number of intermediate cells can be observed, and these increase gradually with the advance of pregnancy; but decrease just before delivery. The cornification index is, however, low and keeps on decreasing gradually but it tends to rise before delivery. In the seven cases whose cleanliness has been poor throughout the period the percentage of intermediate cells is low, showing not much variations. The cornification index shows a high percentage with marked fluctuations, and gradually decreasing with the advance of pregnancy, it shows a slight increasing tendency just before delivery. In 12 cases whose cleanliness varied during the period the vaginal smear picture presents a tendency to change the number of various cells above mentioned in proportion to the changes in the clenaliness. 2. Because there is a tendency to present variations in the number of cells, an increase in leucocyte count and mucus content, the dissemination of cells and a decrease in the stainability of cells during the period before delivery as a forementioned, from these changes in cytological picture it is possible to determine the time of delivery to a certain extent. On the observations in 275 cases the rate of reliability in such a determination amounted to 68 per cent, but it was difficult in those with a low degree of cleanliness. 3. In 15 cases of miscarriage the cornification index and acidophilic index were low, with increase in the leucocyte count and mucus content, but similar findings were revealed even in normal pregnancy with a low level of cleanliness, making it difficult to diagnose accurately.