First trimester abortions induced by a single extraovular injection of prostaglandin F2α

Comparison Between Prostaglandin E2 and Oxytocin Actions on Pregnant Mouse Myometrium

“…This was called 'Progesterone block' and could maintain pregnancy. Progesterone might modify the actions of PGE2 and oxytocin on the myometrium, since the sensitivity of the myometrium is closely related to the progress of gestation (CSAPO et al, 1972(CSAPO et al, , 1973. However it has also been reported in the human myometrium by SPEROFF et al(1972) that a significant decrease in oestriol levels preceded the decrease in oestradiol during PG infusion and no significant change in progesterone concentration in the blood is seen prior to abortion.…”

INTRAMUSCULAR 15(S)15 METHYL PGF2α FOR MENSTRUAL REGULATION

“…The mechanism by which prostaglandins bring about menses induction is not clear. Csapo (2) proposed the "Impact" theory of prostaglandins for induction of abortion. Fleischer et al (7) developed a model for early pregnancy interruption and supported Csapo's hypothesis.…”

“…The methods used at present for termination of early pregnancy i.e., within two to three weeks of missed period are surgical, mostly vacuum aspiration and occasionally dilatation and curettage. The possibility of using prostaglandins to develop a non-surgical method has been considered since 1971, when natural prostaglandins PGF2a and PGE2 were used by vaginal route (1) or intrauterine route (2). With the introduction of potent PGF2a and PGE 2 analogues, high efficacy with better predictable responses and less side effects could be achieved.…”

Morphological changes in the placenta and decidua after induction of abortion by extra‐amniotic prostaglandin

“…This topic has been the subject of several recent detailed reviews (Karim & Hillier 1975, Karim & Amy 1975, Thiery & Amy 1975) and in essence there are two schools of thought, one maintaining that the abortifacient action is due solely to a direct stimulatory effect on the myometrium and the other suggesting that the basic action of prostaglandins is to inhibit placental synthesis of progesterone either directly, by acting on the placenta itself, or indirectly, by restricting the utero-placental blood flow as a result of either vasoconstriction of the maternal vessels or protracted myometrial contraction. The progenitor of what might be termed the 'progesterone hypothesis' has been Csapo who, together with his colleagues, has argued that prostaglandins alone can only stimulate the myometrium to a tetanic contraction and that cyclic contractions are not initiated until, or unless, the progesterone block mechanism, which inhibits cyclic myometrial activity, is overcome , Csapo, Ruttner & Wiest 1972, Csapo, Kivikoski, Pulkkinen & Wiest 1972. This dispute as to the importance of progesterone still continues and has not been resolved by studies of plasma progesterone levels in prostaglandin-induced abortion, some of which have demonstrated that the progesterone level falls before abortion occurs and others concluding that progesterone values are maintained until the placenta has separated.…”