[Does the site of the placenta in the area of the caudal section of the uterus change during pregnancy? An echographic observation of the course of pregnancy (author's transl)].

Via examinations by ultrasonic sectional view during the course of pregnancy, the growth of the placenta was followed in 52 pregnant women. When a pathologic location of the placenta could be excluded during the first examination in the second trimester (26 cases), secondary development of a pathologic insertion was not observed. In 26 cases in which a pathological location of the placenta could be established before the 20th gestation week, a cranial shift in the caudal placenta border of up to 8 cm could be established in 19 cases. A pathological location of the placenta diagnosed in the second trimester can disappear. The shape of the uterus and the alterations in the spacial relationship between placenta and internal os uteri were caused by the development and stretching of the lower segment of the uterus. The vaginal hemorrhages in the second trimester caused by a low placental insertion (13 cases) stopped (with the exception of 2 cases) at the latest after the 6th month of pregnancy. The definitive establishment of a placenta pravia before the 5th-6th month of pregnancy is virtually impossible sonographically.