PLACENTAL LOCALIZATION - A COMPARISON BETWEEN ULTRASONIC COMPOUND B SCANNING AND RADIOISOTOPE SCANNING

Placental localization using 99mTc-HSA scintillation scanning has been compared with ultrasonic compound B scanning in 50 patients. Both methods gave accurate localization of the placenta, and there was agreement between them in 46 patients. Ultrasound scanning is superior to radioisotope scanning, as it visualizes the fetus, and by the use of the full bladder technique, it permits determination of the precise relation of the placenta to the internal os of the uterus, a method independent of surface landmarks. Although the dose of irradiation with 99mTc-HSA scanning is very small, there is no radiation or other hazard with ultrasound. However, the ultrasonogram requires more experience in interpretation than the radioisotope scan. It is suggested that ultrasound placentography is the method of choice in a large obstetric unit, while radioisotope scanning is more suitable for a small obstetric unit in a general hospital. © 1969.