The efficacy and acceptability of the ″prostaglandin impact″ in inducing complete abortion during the second week after the missed menstrual period

Twenty-two pregnant patients were exposed, 12±1 days after their missed menstrual period, to a single intrauterine dose of 5mg PG F2_α, to provoke a PG ″Impact″ (PGI) and through it legal abortion. The PGI, delivered through the cervix during 10 minutes, induced 83±9mm Hg contracture in 20±3 minutes. Cyclic IUP reached 102±10mm Hg only in 116±14 minutes, it was then sustained for about 2 hours and subsequently declined.During the evolution of IUP uterine bleeding appeared, progesterone (P) and estradiol 17_β (E₂) started to decrease and continued decreasing. At 24 hours after PGI, P-withdrawal was 44% (P<0.05), bleeding continued and cervical dilatation approximated 1cm. Subsequently uterine bleeding (containing tissue fragments) continued and out of 22 women 20 aborted completely. After 3–5 days bleeding declined, the pregnancy tests became negative and normal menstrual periods one month after PGI provided the desired end points of the study. Complete abortions, simulating the symptoms of delayed menstrual periods, had a high Abortion Score of 95 and in the sedated patients the side effects were infrequent, mild and acceptable. This clinical outcome encourages extensive field trials.None of the patients aborted during the short lived period of exogenous PG stimulation. However, the continued steroid withdrawals indicated that PGI damaged the endocrine function of the ovum and the luteotrophic support of the corpus luteum. Therefore, if it was PG which completed abortion eventually, it had to be the endogenous compound, having become effective in physiological concentrations, due to the threshold-lowering action of P-withdrawal.     

Suppression of uterine activity and abortion by inhibition of prostaglandin synthesis

The premise has been examined that the evolution of uterine activity, provoked by progesterone(P)-deficiency and consequent prostaglandin(PG)-dominance, can be suppressed in patients by inhibiting PG-synthesis. In 20 midtrimester pregnant women P-deficiency, evolution of intrauterine pressure (IUP), oxytocin response (OR) and abortion had been induced by the hypertonic saline technique and the changes in P and E2 levels and in IUP and OR measured sequentially. According to a "double blind" protocol, 10 volunteers received placebo, while another 10 were treated during 14 hours with 1050 mg naproxen, an inhibitor of PG-synthesis. Significant decrease in plasma progesterone (P 0.001) and estradiol 17Beta (P 0.02) preceding clinical progress in abortion demonstrated that hypertonic saline suppressed the endocrine function of the fetoplacental unit in both groups of patients. In spite of a 40% reduction in the P-levels of the experimental group (at a time when the controls aborted) the evolution of IUP, OR and abortion in the naproxen treated had been delayed by about 30 hours. This significant delay in all the measured parameters (P 0.001) is evidence that inhibition of PG-synthesis prevents the endogenous activation of the uterus in patients, as it does in animal "models".     

The termination of first trimester pregnancy by extraovular “Prostaglandin-impact”

In 30 sedated volunteers first trimester pregnancy had been successfully terminated with Csapo's method of “Prostaglandin-Impact” (1). The patients were 24.1±0.4 years of age, 9.2±0.4 weeks pregnant, para 0.4±0.1. They all received an extraovular dose of 10 mg PG F2α, under intravenous sedation (100 mg pethidium hydrochloride, 50 mg DPP hydrochloride and 0.5 mg atropinum sulfate). Those 15 (out of 30) patients, whose clinical progress was slow received at 8 hours after the first PG Impact (PGI) a 2nd dose of 5 mg PG F2α, increasing the total average dose to 12.5± 0.5 mg.PGI invariably provoked a rapid and high level uterine contracture. At 4 hours after PGI plasma progesterone (P) already decreased by 20% and cyclic intrauterine pressure was in distinct evolution. At 8 hours after PGI, 15 of the 30 patients showed advanced clinical progress and 33% decrease in P levels. These women aborted in 10.2±1.1 hours, when their P levels decreased by 45% (P < 0.001). Abortion was complete in 13 and incomplete in 2 of the patients. The remaining 15 women, whose clinical progress was indistinct at 8 hours after PGI and whose P levels only decreased by 25% received a 2nd dose of 5 mg PG F2α. These women aborted after 18.5±1.5 hours, 9 completely and 6 incompletely, when their P levels decreased (as in the previous group) by 45% (P < 0.001).All the 30 patients aborted after a short IAT of 14.3±1.2 hours. Abortion was complete in 22 women, while 8 retained various amounts of placental tissue. The “Abortion Score” was high, 94.7±1.6. Only 13 patients had side effects, shortly after PGI, manifesting in vomiting and nausea, which were transient and mild. There were no complications during the study and followup. These findings confirm earlier results (1). When supplemented by extensive field trials, the technique of extraovular PGI might be broadly considered for the non-surgical termination of 1st trimester pregnancy.     

The abortifacient action of the extraovular “Prostaglandin impact” during the first half of human pregnancy

In 30 volunteers, 7 to 22 weeks pregnant, legal abortion had been induced successfully with the extraovular “Prostaglandin Impact” (PGI) (1). The patients were 24.8±1.1 years old (Means ± S.E.), para 1.6±0.3. At the 14.8±0.7 weeks of pregnancy and under sedation an initial dose of 10.0±0.0 mg PG F2α had been delivered transcervically into their extraovular (E.O.) space. This dose had been increased if accidental rupture of their fetal membranes resulted in intraamniotic (I.A.) treatment. The initial PGI of 16.0±2.0 mg was supplemented by additional PG doses, up to 27.0±2.9 mg, if clinical progress was slow. The patients responded to the initial PGI with sustained uterine contracture; rapid and continued progesterone (P) withdrawal, from 59.9±3.0 ng/ml to 30.7±2.1 ng/ml (49%); and with the progress of time high level cyclic intrauterine pressure (IUP). The 26% P-withdrawal, measured 3 hours after PGI was already significant (P < 0.001). Abortion was complete in 25 and incomplete in 4 patients, while 1 gravida had been curetted at 2 cm cervical dilatation. The instillation-abortion time (IAT) was short, only 13.0±1.1 hours. No side effects were observed in 17 patients, while 8 gravidas vomited (usually once) and 5 had transient increase in blood pressure. Extensive laboratory tests revealed no significant deviations from normality, during and after PG treatment. Blood transfusion was given to 2 patients (partly detached placentae and hemorrhage), antibiotics resolved 2 cases of endometritis and curettage removed (2 weeks after abortion) a small placental residue.The fetal membranes were accidentally ruptured in 11 patients and in these women the slow contracture response of the uterus signaled I.A. (rather than E.O.) PGI. The initial PG dose was increased, therefore, from 10.0±0.0 mg to 25.9±3.9 mg (P < 0.001) and the total dose from 20.0±2.0 to 42.3±4.8 mg (P < 0.001), to compensate for the lesser efficacious I.A. administration. In spite of this massive increase in the initial and total doses of PG, the rate and degree of P-withdrawal, the IAT, the incidence of side effects and the “Abortion Score” (AbS) of these 11 patients were similar to those of the 19 gravidas who received E.O. PGI. This finding, the good clinical outcome of the earlier (1) and the present study suggests that the transcervical E.O. PGI (regardless of accidental I.A. treatment) is a recommendable procedure for the non-surgical termination of pregnancy during the 1st half of gestation.     

孕激素及人绒毛促性腺激素与药物流产后异常子宫出血的关系

目的:分析孕激素和人绒毛膜促性腺激素(h CG)与药物流产后异常子宫出血的关系。方法:选择2017年1月至2017年12月我院妇产科收治的药物终止妊娠的妇女150例,患者口服米非司酮配伍米索前列醇药物终止早期妊娠。将药物流产后子宫出血时间≤14 d作为对照组(n=75),14d作为异常组(n=75)。比较两组患者在药物流产后10 d、14 d、18 d、22 d血清中孕激素和h CG含量,分析两组患者孕激素和h CG含量相关性。结果:两组患者在年龄、月经周期、孕次、受孕天数、体重等方面比较无统计学差异(P0.05)。异常组在药物流产后10 d、14 d、18 d、22 d血清孕激素和h CG含量均高于对照组(P0.05)。两组患者在药物流产后10 d、14 d、18 d、22 d孕激素含量呈先降低再升高的趋势(P0.05)。对照组患者在药物流产后10 d、14 d、18 d、22 d血清hCG含量逐渐降低(P0.05);异常组在药物流产后10 d、14 d血清h CG含量比较无统计学差异(P0.05),在药物流产后18 d、22 d血清hCG含量低于药物流产后10 d、14 d,且药物流产后22 d低于药物流产后18 d(P0.05)。对全部样本的全部时点数据合并进行Pearson相关检验分析,孕激素和h CG含量呈正相关关系(P0.05)。结论:药物流产后异常子宫出血妇女血清的孕激素、hCG含量较高,两者呈正相关关系。药物流产后10 d、14 d监测血清HCG值无明显下降提示有异常子宫出血的可能,联合监测孕激素、hCG含量有利于药物流产后异常子宫出血的预测和治疗。     

Pregnancy-specific protein B and progesterone in monitoring viability of the embryo in early pregnancy in the cow after experimental infection with Actinomyces pyogenes

Actinomyces pyogenes can cause embryonic death and abortion during the early stages of pregnancy in cows. Bovine pregnancy-specific protein B (PSPB) is produced in response to a viable embryo and as such it could be a potential marker for embryronic survival. The plasma concentration of PSPB was monitored in cows following an intrauterine infection with A. pyogenes and during the subsequent abortion and recovery from infection. Plasma progesterone concentrations were also monitored, and the results were compared withthose for animals in which abortion had been induced by prostaglandin F2alpha treatment. In abortions induced both by infection and by cloprostenol, the plasma concentration of PSPB fell steadily from the day of treatment, with a half-life of 7 days. In the cloprostenol-induced abortions, progesterone levels fell dramatically to <0.5ng/ml within 24 hours of treatment, while following inoculation with A. pyogenes , progesterone concentration remained elevated for 20 to 40 days and fell to <0.5ng/ml after evacuation of pus from the uterus. Sequential monitoring of PSPB, which identifies embryonic death when a continuing fall in plasma concentration is demonstrated, is a better indicator of embryonic death following bacterial infection with A. pyogenes than plasma progesterone concentration, which falls only when infection is resolved.     

Prostaglandins and post-abortion luteolysis in early pregnancy.

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF2alpha(15-me-PGF2alpha) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400mug 15-me-PGF2alpha extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly duriing the same period. Under the experimental conditions of this study neither 15-me-PGF2alpha nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Induction of labour with prostaglandin E2 gel in cases of intrauterine fetal death.

In established intrauterine fetal death, 20 patients were treated with prostaglandin E2 gel administered extraamniotically. The results were compared with those of another group of 20 patients who had received combined treatment. In this group, one or more of the following agents had been administered :- i.v. oxytocin, 20% NaCl solution or Premarin instilled intraamniotically, introduction of a balloon catheter or Rivanol administered extraamniotically. Average induction-abortion interval for the PG group was about 12 hours while for the second group it was about 30 hours. The side effects observed were slight in both groups. The results show that administration of PG-gel can be used with advantage in fetal demise because of the relatively short induction-abortion intervals obtained, the insignificant side effects and the low dose of PG required.     

Induction of labour with prostaglandin E2 gel in cases of intrauterine fetal death

In established intrauterine fetal death, 20 patients were treated with prostaglandin E₂ gel administered extraamniotically. The results were compared with those of another group of 20 patients who had received combined treatment. In this group, one or more of the following agents had been administered: - i.v. oxytocin, 20% NaCl solution or Premarin instilled intraamniotically, introduction of a balloon catheter or Rivanol administered extraamniotically. Average induction-abortion interval for the PG group was about 12 hours while for the second group it was about 30 hours. The side effects observed were slight in both groups. The results show that administration of PG-gel can be used with advantage in fetal demise because of the relatively short induction-abortion intervals obtained, the insignificant side effects and the low dose of PG required.     

Massive initial prostaglandin impact in postconceptional therapy

The abortifacient effect of an initial PGF2alpha impact was examined in 10 obstetrically normal first trimester pregnant patients. Sedated patients were given extraamniotically an average initial dose of 8.1 + or - 0.8 mg PGF2alpha during a 10 minute instillation. Side effects occurred occasionally but were minimal. Uterine contracture developed rapidly reaching an average pressure of 83.2 + or - 11.3mm Hg in about 20 minutes and then slightly declined in time. Superimposed on the contracture response were gradually increasing cyclic changes in intrauterine pressure which reached a magnitude of 129.8 + or - 12.2mm Hg by 10 hours after initial treatment. Initial therapy was augmented in some cases by an average of 4mg PGF2alpha; only 4 patients required oxytocin supportive therapy. The patients aborted in an average of 10.9 + or - 2.0 hours. 7 aborted completely, 2 left behind small placental residues, and 1 retained the placenta during a period of 11.5 hours. An (AbS) abortion score of 92 was obtained in the study which is the highest in 6 consecutive studies using various methods of PGF2alpha administration. Plasma estradiol-17beta and progesterone levels decreased continuously during the instillation abortion time in the complete aborters, while the incomplete aborters showed lesser changes. It is concluded that massive intrauterine PGF2alpha injection is a more efficacious and acceptable form of postconceptional therapy than protracted treatment. Such therapy appears to convert the refractory uterus into a spontaneously active and pharmacologiclly reactive organ by inducing vasoconstriction, myometrial stretch, and fetoplacental insufficiency.     

Progesterone withdrawal induced by ICI 81008 in pregnant rats

Of a total of 343 pregnant rats treated with the prostaglandin F2 analogue ICI 81008, 137 aborted, while 83 had reduced and 123 intact litter. These biological variations depended primarily on the gestational timing of treatment and on the dose and route of administration of this synthetic PG. In comparison with the 107 controls, all experimental rats which aborted had a drastic reduction in plasma progesterone levels which was highly significant (P<0.001) until day 18. In contrast, those animals which escaped suboptimal ICI 81008 treatment with a partly resorbed litter, only had a moderate reduction in progesterone which was statistically significant (P<0.01) until day 16 when the levels of this steroid normally begin to decrease. Ineffective treatment did not affect progesterone levels and intact pregnancy. In contrast to progesterone, there was no correlation between plasma estradiol-17β levels and the consequences of ICI 81008 treatment.

ICI 81008 was most effective between the 6th and 12th days of gestation, when plasma progesterone in the normal controls showed a nadir. Effective treatment reduced plasma progesterone within 6 hours. Evidently the pharmacologically provoked endocrine imbalance precedes the cessation of characteristic gestational weight gain, uterine bleeding and abortion which only manifest 24 to 48 hours after treatment.     

Prostaglandins and post-abortion luteolysis in early pregnancy

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF₂ (15-me-PGF₂) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400g 15-me-PGF₂ extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly during the same period. Under the experimental conditions of this study, neither 15-me-PGF₂ nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Treatment with a single vaginal suppository containing 15-methyl PGF2 alpha methyl ester at expected time of menstruation.

Termination of early pregnancy, by vaginal administration of prostaglandin analogues, one to three weeks after the first missed menstrual period, has advantages and disadvantages in comparison with vacuum aspiration. Some of these may be reduced if the patient is treated earlier. In the present study the effect and safety of one vaginal administration of 2.5 to 3 mg 15-methyl-PGF2 alpha methyl ester around the expected time of menstruation was evaluated in 16 women exposed to the risk of pregnancy. The overall number of treatment cycles was 35 and pregnancy was confirmed by plasma beta-HCG in eight. The treatment resulted in bleeding in all the pregnant cycles while in the nonpregnant ones it only provoked spotting and bleeding did not begin until the expected time of menstruation. Treatment with 2.5 mg 15-methyl-PGF2 alpha methyl ester resulted in complete abortion in one of three women. If the dose was increased to 3 mg all five treated women aborted. In nonpregnant patients no changes in the levels of estradiol-17 beta or progesterone at any time during the 24-hour observation period were found. Serum cortisol and prolactin but not TSH levels started to increase two hours after the start of treatment and reached a maximum after five hours. The increase coincided with the onset of uterine pain. Ovulatory cycles as judged from basal body temperature occurred in the first menstrual cycle following treatment in all nonpregnant patients. Although possible to use as a "once a month treatment" it seems preferable since the dose is the same, to postpone treatment until menstruation is delayed for a week or more.     

Treatment with a single vaginal suppository containing 15-methyl PGF2α methyl ester at expected time of menstruation

Termination of early pregnancy, by vaginal administration of prostaglandin analogues, one to three weeks after the first missed menstrual period, has advantages and disadvantages in comparison with vacuum aspiration. Some of these may be reduced if the patient is treated earlier. In the present study the effect and safety of one vaginal administration of 2.5 to 3 mg 15-methyl-PGF_2α methyl ester around the expected time of menstruation was evaluated in 16 women exposed to the risk of pregnancy.The overall number of treatment cycles was 35 and pregnancy was confirmed by plasma β-HCG in eight. The treatment resulted in bleeding in all the pregnant cycles while in the nonpregnant ones it only provoked spotting and bleeding did not begin until the expected time of menstruation. Treatment with 2.5 mg 15-methyl-PGF_2α methyl ester resulted in complete abortion in one of three women. If the dose was increased to 3 mg all five treated women aborted. In nonpregnant patients no changes in the levels of estradiol-17β or progesterone at any time during the 24-hour observation period were found. Serum cortisol and prolactin but not TSH levels started to increase two hours after the start of treatment and reached a maximum after five hours. The increase coincided with the onset of uterine pain.Ovulatory cycles as judged from basal body temperature occurred in the first menstrual cycle following treatment in all nonpregnant patients. Although possible to use as a “once a month treatment” it seems preferable since the dose is the same, to postpone treatment until menstruation is delayed for a week or more.     

Prostaglandin-induced luteolysis in pregnant and pseudopregnant rabbits and the resultant effects on the myometrial activity.

The effect of prostaglandin (PG)-induced luteolysis on the myometrial activity in 20--21-day-pregnant and 11--12-day-pseudopregnant rabbits was studied by intrauterine pressure (IUP) recording during PG infusions. The same dose of PG (10 micrograms/h during 8h) was also given to 7 non-pregnant (untreated) does that were used as controls. Peripheral plasma concentration of progesterone and oestradiol-17 beta were measured at 2-h intervals during the infusion. Plasma progesterone level decreased significantly within 2 h or the start of infusion in pregnant and pseudopregnant does and continued to decrease; at the end of 8 h, the concentrations were 31 and 41%, respectively, of the pre-infusion levels. The amplitude of uterine contractions increased significantly after 4 h in pseudopregnant does, increased slightly but insignificantly in the pregnant does and showed no significant change in the non-pregnant does during PG infusion. The amplitudes developed in the pregnant and pseudopregnant does were significantly different. The direct effect of progesterone (1--3 micrograms/h during 4 h) was also studied in 7 non-pregnant rabbits. After 2 h the amplitude of contractions had decreased markedly and the pattern of activity had become irregular. The results support the concept of a myometrial inhibitory factor other than progesterone in rabbit pregnancy and suggest that this factor(s) originates in conceptus.     

Effect of prostaglandin F2 alpha on the secretion of human prolactin

This study examines the role of PGF2a (prostaglandin F2alpha) in increasing the secretion rate of human prolactin. 11 women (mean gestational period, 18 weeks) seeking pregnancy termination were divided into 4 groups: 1) Group 1 consisted of 6 women who received 30 mg initially of PGF2a injected intramuscularly and an additional 15 mg after 24 hours if abortion had not occured; mean induction to termination period was 38 hours; 2) Group 2 comprised of 3 women who received PGF2a (500-1500 ug) via the transcervical route at 1 to 2 hourly interval; average number of injections was 20; mean induction to termination period, 24 hours; 3) Group 3 had 2 women receiving hypertonic saline by intraamniotic injection; mean induction to termination period was 51 hours; 4) Group 4 had 4 women who served as controls; mean observation period, 20 hours. Venous blood samples were heparinized in tubes at intervals of 2 to 3 hours. A homologous radioimmunoassay using highly purified human prolactin (for iodination and standards) plus rabbit antihuman prolactin measured serum prolactin. Spikes of serum prolactin up to 550 ng/ml were observed at irregular intervals in 5 women in Group 1; the spikes were less frequent and of smaller amplitude in Groups 3 and 4. The increase in serum prolactin was dramatic and more sustained in Group 2 patients and peaked towards the end of the prostaglandin infusion. Serum prolactin of Group 2 patients were significantly higher than those of Groups 3 and 4 (p0.01). 5 of 9 women whose pregnancies were terminated by PGF2a lactated. However, there was no significant difference between the mean serum prolactin levels in women who lactated (136 ng/ml) and those who did not (120 ng/ml). Although PGF2a is not a lactogenic hormone, this study shows that PGF2a stimulates the secretion of human prolactin during second trimester pregnancy. The fact that the transcervical route caused a significant increase in serum prolactin and the intraamniotic route did not is attributed to the increased systemic absorption of PGF2a following transcervical administration. No correlation was seen between the presence or absence of lactation and the serum prolactin level following pregnancy termination with PGF2a.     

Prostaglandins and post-abortion luteolysis in early pregnancy

This study was undertaken to determine if post-abortion luteolysis in early pregnancy could be accelerated by the administration of 15(S)15-methyl-PGF_2α (15-me-PGF_2α) or delayed following pretreatment with indomethacin. Thirty-nine women were divided into four groups: 7 women were given 400μg 15-me-PGF_2α extra-amniotically one hour prior to vacuum aspiration; 14 were pretreated with oral indomethacin (50 mg X4) over 24 hours; 7 were given indomethacin (50mg X 6) over 36 hours and 11 served as controls. Plasma progesterone and estradiol were measured at fixed intervals before and after abortion. There was a rapid drop in the plasma progesterone within the first hour after abortion followed by an exponential decline over the next 23 hours. The plasma estradiol fell rapidly during the same period. Under the experimental conditions of this study, neither 15-me-PGF_2α nor indomethacin exerted a significant effect on the decline in luteal function. These results are interpreted as suggesting that factors other than prostaglandins have a more significant role in post-abortion luteolysis.     

Prostaglandin E2 induced abortion with vaginal suppositories in a contraceptive diaphragm

PGE2 (prostaglandin E2), 20 mgm vaginal suppositories were administered to 2 groups of women seeking termination of pregnancy. 1 group had the suppository inserted inside a contraceptive diaphragm. Statistical comparisons were carried out for instillation to abortion time, side effects, and intrauterine pressure parameters. The usage of the diaphragm significantly reduced side effects, and resulted in an instillation to abortion time of 12.8 + or - 2.3 hours with no failures. The quantitative analysis of the uterine pressure recordings revealed activity significantly different than that seen with intraamniotic or extraovular PGF2alpha. The development of uterine activity simulates that of normal labor in that elevation of resting pressure does not occur and maximum active pressure evolves slowly.     

Prostaglandin E2 induced abortion with vaginal suppositories in a contraceptive diaphragm

Prostaglandin E₂, 20 mgm vaginal suppositories were administered to two groups of women seeking termination of pregnancy. One group had the suppository inserted inside a contraceptive diaphragm. Statistical comparisons were carried out for instillation to abortion time, side effects, and intra-uterine pressure parameters. The usage of the diaphragm significantly reduced side effects, and resulted in an instillation to abortion time of 12.8 ± 2.3 hours with no failures. The quantitative analysis of the uterine pressure recordings revealed activity significantly different than that seen with intra-amniotic or extra-ovular PG F_2α. The development of uterine activity simulates that of normal labor in that elevation of resting pressure does not occur and maximum active pressure evolves slowly.     

Early pregnancy-abortion model using sulprostone

Sulprostone has been demonstrated to be effective as a parenteral abortifacient, but not as a vaginal suppository. A vaginal preparation was given to 19 women to determine its mechanism of action, and to confirm the principle of uterine conversion as a biological model for the induction of an early abortion.The drug was administered to women with confirmed pregnancies and amenorrhea and not exceeding 49 days. A 95% success rate was obtained with an incidence of drug related side effects of 20% as opposed to the general 80–90% figure of PGE₂ and F₂a. The hormone profile obtained revealed a parallel fall in hCG and estradiol, and progesterone.This study confirms the value of uterine conversion, a concept that describes the change in uterine reactivity following PG administration and determines the phase when uterine activity is no longer dependent on exogenous oxytocic medication.