The kinetics of extraamniotically injected prostaglandins to induce midtrimester abortion.

In an attempt to improve the extraamniotic administration of prostaglandins in effecting abortion, the movement of injected prostaglandins in a high or low viscosity medium has been observed by radiological studies and radioimmunoassy of PGE and PGFalpha in amniotic fluid and maternal plasma in association with intrauterine tocographic responses. Results obtained suggest that the immediate response by the uterus is a reflection of the speed of absorption of prostaglandins from the chorio-decidual space and that this influences the outcome in inducing abortion within 24 hours. By giving the prostaglandins in a viscous medium a slower release of prostaglandins was produced in most cases, which probably accounts for the greater efficacy obtained using single injections of prostaglandins in this vehicle compared with normal saline.