Circulation parameters in the human uteroplacental region studied by a radioactive method

Maternal placental circulation is of great importance, especially in pathological pregnancies, but methods of functional assessment have not been effective. The method used is based on a follow-up of the dynamic behavior of 113mIntracer labeling the mothers's blood at the uteroplacental region. After localization of the placenta two exponential curves of the dynamic behavior of the tracer, one placental and the other myometrial, were obtained. The measurement was made in the third trimester of pregnancy in 30 women with pathological pregnancies and in 51 pregnant control subjects. The clinically sensitive criteria for distinguishing between pathological and control placentas were found to be the ration between the specific blood flow in the placenta and that in the myometrium (lambda p/lambda m) and the slope (alpha) of the straight line passing through the points of this ratio. The value of lambda p/lambda m for pathological pregnancies was 5.4 +/- 1.0 (SD) vs 1.7 +/- 0.6 in control pregnancies, and the value of alpha for pathological cases was 6.3 compared with 1.5 for control subjects. These tests may be useful in the diagnosis of pathological pregnancies with interference in uteroplacental circulation.