Ultrasonic placentography

A series of 400 consecutive ultrasonic placentographies is presented, representing the total of patients scanned since the installation of a Diasonograph† in a busy district general hospital. It is often difficult to be absolutely certain that the diagnosis made by sonar is correct. In this series an assessment of accuracy has been denned as follows: The diagnosis is deemed to be correct when either proved at Caesarean section or manual removal of the placenta, or when the outcome of the pregnancy was in accordance with the ultrasonic diagnosis. In all but three cases the placenta was localized by its characteristic appearance on the screen. When the placenta was situated in the upper segment of the uterus, the incidence on the anterior and posterior walls was approximately equal, but when situated in the lower segment, posterior praeviae placentae outnumbered anterior. Predominantly lateral and fundal insertions are uncommon. In the whole series, the total number of cases where the diagnosis was proved wrong either by operative findings or by the outcome of labour being at total variance with the ultrasonic report, was 14 (3·5 per cent). There were a further eight cases (2·4 per cent) in which the diagnosis was possibly wrong but the clinical outcome was in accordance with the diagnosis which was made. It is concluded that ultrasonic placentography is a safe, simple and reliable method of placental localization.