Decrease of utero-placental blood flow during prostaglandin F2alpha induced abortion.

Pregnancy had been terminated in 6 normal midtrimester pregnant patients by the extraovular injection of 10 mg prostaglandin F2alpha (PGF2alpha). In these 6 Experimental and 3 Control patients utero-placental blood flow had been measured, by changes in the density of radioactive Indium, distributed over the uterine area, as a function of time. In comparison with Controls utero-placental blood flow decreased in the Experimental patients already at 5 minutes after PG-treatment, long before advanced cyclic IUP evolved. This finding substantiates the conclusion (1-3), based on experiments in animal "models', that decrease in utero-placental blood flow is an early step in the mechanism of PG action.