Effect of mifepristone on dilatation of the pregnant and non-pregnant cervix

Uterine cervical stenosis: from classification to advances in management. Overcoming the obstacles to access the uterine cavity

BACKGROUND

To date hysteroscopy is the gold standard technique for the evaluation and management of intrauterine pathologies. The cervical canal represents the access route to the uterine cavity. The presence of cervical stenosis often makes entry into the uterine cavity difficult and occasionally impossible. Cervical stenosis has a multifactorial etiology. It is the result of adhesion processes that can lead to the narrowing or total obliteration of the cervical canal.

PURPOSE

In this review, we summarize the scientific evidence about cervical stenosis, aiming to identify the best strategy to overcome this challenging condition.

METHODS

The literature review followed the scale for the quality assessment of narrative review articles (SANRA). All articles describing the hysteroscopic management of cervical stenosis were considered eligible. Only original papers that reported data on the topic were included.

RESULTS

Various strategies have been proposed to address cervical stenosis, including surgical and non-surgical methods. Medical treatments such as the preprocedural use of cervical-ripening agents or osmotic dilators have been explored. Surgical options include the use of cervical dilators and hysteroscopic treatments.

CONCLUSIONS

Cervical stenosis can present challenges in achieving successful intrauterine procedures. Operative hysteroscopy has been shown to have the highest success rate, particularly in cases of severe cervical stenosis, and is currently considered the gold standard for managing this condition. Despite the availability of miniaturized instruments that have made the management of cervical stenosis more feasible, it remains a complex task, even for experienced hysteroscopists.

Comparison of outpatient with inpatient mifepristone usage for cervical ripening: A randomised controlled trial

Purpose

The efficacy and safety of using mifepristone for the preinduction/induction of labour (IOL) as the only method or in combination with others has been confirmed in observational and randomised trials. However, there are currently no studies comparing the efficacy and safety of using mifepristone for the preinduction of labour on an inpatient and outpatient basis.

Objective

To evaluate whether the outpatient use of mifepristone for cervical ripening before IOL at term is as efficient and safe as in inpatients.

Study design

This open-label, prospective, two-arm, non-inferiority randomised controlled trial (ISRCTN26164110) with a 1:1 allocation ratio was conducted in a single tertiary referral hospital. Overall, 322 pregnant women (gestational age: 39-41 weeks; Bishop score < 6, intact membranes, no contraindications for vaginal delivery, and no contraindications for IOL) were included and randomised:162 to the outpatient group and 160 to the inpatient group for cervical ripening with mifepristone. Analyses were performed based on the intention-to-treat principle.

Results

In 16 % and 17 % of the cases, labour began spontaneously within 24-36 h after taking mifepristone tablets. The additional use of prostaglandin E2 or a balloon for cervical ripening occurred equally often in the compared groups. Oxytocin was used more frequently to induce labour in the inpatient group (P = 0.035). There was no difference in the length of the interval from the onset of cervical ripening to the onset of labour between the groups (38.6 vs. 38.8 h, P = 0.900). The failed induction rate was 1.85 % vs. 0.63 % (P = 0.346).Regional analgesia (P = 0.011) and abnormal foetal heart rate patterns (P = 0.027) were more common in the inpatient group. In the outpatient mifepristone preinduction group, the average time interval from hospitalisation to discharge was 25 h shorter (P < 0.001). No statistically significant differences were observed between the groups in terms of the rates of adverse side effects or perinatal outcomes.

Conclusion

Outpatient cervical ripening with mifepristone reduced the hospital stay duration compared to inpatient ripening, with no difference in efficacy in terms of improvement in the Bishop score, frequency of additional induction method usage, interval from start of preinduction to onset of labour, and labour duration.No differences in the delivery methods, failure rates, or perinatal outcomes were observed. The frequency of adverse effects was low and not related to the setting of the preinduction site. Cervical ripening with mifepristone can be performed on an outpatient basis, because it is as effective and safe as inpatient ripening.

Clinical Utility of Mifepristone: Apprising the Expanding Horizons

Mifepristone is a progesterone and glucocorticoid receptor antagonist. Medical abortion with mifepristone and prostaglandin has revolutionized the abortion process extending abortion care to the doors of females. From as low as 2 mg/day to doses extending to 600 mg, from daily dosing to single dosage treatment, mifepristone has a wide perspective in the treatment of various pathologies. Cervical dilatation and myometrial contractility have made the utility of mifepristone feasible for second-trimester termination of pregnancy and induction of labor awaiting Food and Drug Administration approvals. Its anti-progesterone action on the menstrual cycle has a new dimension of use as a contraceptive, as well as use as a menstruation inductive agent. Its role in endometriosis, ectopic pregnancy, and adenomyosis requires more intensive research. Apoptotic action of mifepristone, interference of heterotypic cell adhesion to the basement membrane, cell migration, growth inhibition of various cancer cell lines, decreased epidermal growth factor expression, suppression of invasive and metastatic cancer potential, increase in tumor necrosis factor, downregulation of cyclin-dependent kinase 2, B-cell lymphoma 2, and Nuclear factor kappa B have opened its potential to be explored as anti-cancer treatment and its effects on leiomyoma. The drug needs to be studied more for the prospectus of its anti-glucocorticoid actions in a wider dimension beyond its acquiescence for the treatment of Cushing syndrome.

Outcomes of mifepristone usage for cervical ripening and induction of labour in full-term pregnancy. Randomized controlled trial

OBJECTIVE

The most commonly used approved indications for mifepristone in obstetrics include: termination of early pregnancy, cervical dilatation prior to abortion, labour induction in case of fetal death in utero. Fewer studies have been conducted on the effect of mifepristone on cervical ripening and induction of labour in term pregnancy with a live fetus. The aim of our study was to evaluate efficacy and safety of mifepristone use for cervical ripening and induction of labour versus expectant management in full-term pregnancy.

STUDY DESIGN

Randomized controlled trial. 149 women were randomized, 74 for cervical ripening and induction with mifepristone (200mg orally at the moment of enrollment and, if applicable, second dose after 24h), 75 - expectant management. Primary outcomes: gain in Bishop Score within 24 and 48-h of mifepristone; number of women going into spontaneous labor within 24, 48 and 72-h of mifepristone; rate of failed induction or expectant management.

SECONDARY OUTCOMES

enrollment-induction to delivery interval; mode of delivery; requirement of oxytocin augmentation, neonatal outcomes.

RESULTS

After 48h from enrollment mean gain in Bishop score was 2.58±1.33 in the induction group and 1.15±0.97 in the expectant group (<0.001). Failed management rate was 5.41% and 2.67%, respectively. Significantly more mifepristone treated women had labour within 24, 48 and 72h from enrollment (RR 15.20 CI 95% 2.06-112.18; RR 6.08 CI 95% 2.73-13.57; RR 2.14 CI 95% 1.04-4.42) (p<0.05). Enrollment-induction to delivery interval was significantly shorter in mifepristone group: 2.69±2.06 vs 3.77±1.86days (p<0.001). Premature rupture of membranes, meconium-stained amniotic fluid were more common in expectant management, but regional analgesia and cephalopelvic disproportion - in induction group. There were no differences in mode of delivery, requirement of oxytocin augmentation and main neonatal outcomes.

CONCLUSION

Mifepristone was efficient on inducing cervical ripening and labour in full-term pregnancy. There were no significant difference in main maternal and neonatal outcomes between mifepristone use and expectant management. There were no serious adverse side effects of mifepristone, but there were some features of the course of labor, like more painful uterine contractions and trend of higher rate of cephalopelvic disproportion, that might be directly related to the mifepristone action.

Efficacy of mifepristone for cervical priming for second-trimester surgical termination of pregnancy

OBJECTIVE

To determine whether mifepristone plus misoprostol was as effective as misoprostol with or without laminaria (depending on gestational age) for cervical preparation for second-trimester termination of pregnancy.

METHODS

A retrospective cohort study was carried out among women who underwent surgical termination between 14 and 19+6 weeks of pregnancy. Those who received preoperative mifepristone were compared with those who did not. The study group received mifepristone plus misoprostol before dilation and evacuation of the uterus between May 2008 and September 2011. The comparison (non-mifepristone) group received misoprostol with or without laminaria between January 2005 and April 2008.

RESULTS

There was no difference between the groups in terms of difficulty of cervical dilation, with an overall relative risk for moderate-difficult dilation in the mifepristone group of 0.91 (95% confidence interval, 0.49-1.68). There was no difference between the groups with regard to complications arising from the procedure.

CONCLUSION

Mifepristone is effective for cervical priming prior to second-trimester dilation and evacuation in both multiparous and primiparous women, without an increase in complication rates.

Practical advice for avoidance of pain associated with insertion of intrauterine contraceptives

Few studies in the scientific literature provide clear direction on the prevention or management of pain associated with intrauterine contraceptive (IUC) placement. Those that have been published have studied small numbers of women and fail to provide definitive conclusions. There are also no guidelines available detailing recognised standard approaches to this problem. The consensus recommendations in this review focus primarily on non-pharmacological and often non-evidence-based interventions. This review includes general considerations, practical recommendations for both routine and more difficult cases and guidance on the optimal choice of instruments. General considerations, including pre-insertion counselling, the setting for the procedure, the confidence and technique of the provider and the interplay between the provider and assistant, can influence women's level of anxiety and, in turn, influence their perception of pain and their overall experience. Further studies are required to refine the optimal strategy for managing pain associated with IUC insertion.

Management of pain associated with the insertion of intrauterine contraceptives

BACKGROUND

Most intrauterine contraception (IUC) placements do not require pain relief. However, small proportions of nulliparous (∼17%) and parous (∼11%) women experience substantial pain that needs to be proactively managed. This review critically evaluates the evidence for pain management strategies, formulates evidence-based recommendations and identifies data gaps and areas for further research.

METHODS

A PubMed literature search was undertaken. Relevant articles on management of pain associated with IUC insertion, published in English between 1980 and November 2012, were identified using the following search terms: ‘intrauterine contraception’, ‘insertion’ and ‘pain’. RCTs were included; further relevant articles were also identified and included as appropriate.

RESULTS

Seventeen studies were identified and included: 12 RCTs and one non-randomized study of pre-insertion oral analgesia, cervical priming and local anaesthesia; one systematic review and one RCT on post-insertion analgesia and two non-randomized studies on non-pharmacological interventions. There was no conclusive evidence that any prophylactic pharmacological intervention reduces pain associated with IUC insertion. However, most of the regimens studied were adopted from hysteroscopy or abortion and effectiveness in specific subsets of women has not been studied adequately. A systematic review found non-steroidal anti-inflammatory agents (NSAID) to be effective in reactively treating post-insertion pain, but no benefit was found with prophylactic use.

CONCLUSIONS

No prophylactic pharmacological intervention has been adequately evaluated to support routine use for pain reduction during or after IUC insertion. Women's anxiety about the procedure may contribute to higher levels of perceived pain, which highlights the importance of counselling, and creating a trustworthy, unhurried and professional atmosphere in which the experience of the provider also has a major role; a situation frequently referred to as ‘verbal anaesthesia’.

Cervical preparation for first trimester surgical abortion

BACKGROUND

Preparing the cervix prior to surgical abortion is intended to make the procedure both easier and safer. Options for cervical preparation include osmotic dilators and pharmacologic agents. Many formulations and regimens are available, and recommendations from professional organizations vary for the use of preparatory techniques in women of different ages, parity or gestational age of the pregnancy.

OBJECTIVES

To determine whether cervical preparation is necessary in the first trimester, and if so, which preparatory agent is preferred.

SEARCH STRATEGY

We searched Cochrane, Popline, Embase, Medline and Lilacs databases for randomised controlled trials investigating the use of cervical preparatory techniques prior to first trimester surgical abortion. In addition, we hand-searched key references and contacted authors to locate unpublished studies or studies not identified in the database searches.

SELECTION CRITERIA

Randomised controlled trials investigating any pharmacologic or mechanical method of cervical preparation, with the exception of nitric oxide donors (the subject of another Cochrane review), administered prior to first trimester surgical abortion were included. Outcome measures must have included the amount of cervical dilation achieved, the procedure duration or difficulty, side-effects, patient satisfaction or adverse events to be included in this review.

DATA COLLECTION AND ANALYSIS

Trials under consideration were evaluated by considering whether inclusion criteria were met as well as methodologic quality. Fifty-one studies were included, resulting in 24 different cervical preparation comparisons. Results are reported as odds ratios (OR) for dichotomous outcomes and weighted mean differences for continuous data.

MAIN RESULTS

When compared to placebo, misoprostol (400-600 microg given vaginally or sublingually), gemeprost, mifepristone (200 or 600 mg), prostaglandin E and F(2alpha) (2.5 mg administered intracervically) demonstrated larger cervical preparation effects. When misoprostol was compared to gemeprost, misoprostol was more effective in preparing the cervix and was associated with fewer gastrointestinal side-effects. For vaginal administration, administration 2 hours prior was less effective than administration 3 hours prior to the abortion. Compared to oral misoprostol administration, the vaginal route was associated with significantly greater initial cervical dilation and lower rates of side-effects; however, sublingual administration 2-3 hours prior to the procedure demonstrated cervical effects superior to vaginal administration.When misoprostol (600 microg oral or 800 microg vaginal) was compared to mifepristone (200 mg administered 24 hours prior to procedure), misoprostol had inferior cervical preparatory effects. Compared to day-prior laminaria tents, 200 or 400 microg vaginal misoprostol showed no differences in the need for further mechanical dilation or length of the procedure; similarly, the osmotic dilators Lamicel and Dilapan showed no differences in cervical ripening when compared to gemeprost, although gemeprost had cervical effects which were superior to laminaria tents. Older prostaglandin regimens (sulprostone, prostaglandin E(2) andF(2alpha)) were associated with high rates of gastrointestinal side-effects and unplanned pregnancy expulsions. Few studies reported women's satisfaction with cervical preparatory techniques.

AUTHORS' CONCLUSIONS

Modern methods of cervical ripening are generally safe, although efficacy and side-effects between methods vary. Reports of adverse events such as cervical laceration or uterine perforation are uncommon overall in this body of evidence and no published study has investigated whether cervical preparation impacts these rare outcomes. Cervical preparation decreases the length of the abortion procedure; this may become increasingly important with increasing gestational age, as mechanical dilation at later gestational ages takes longer and becomes more difficult. These data do not suggest a gestational age where the benefits of cervical dilation outweigh the side-effects, including pain, that women experience with cervical ripening procedures or the prolongation of the time interval before procedure completion. Mifepristone 200 mg, osmotic dilators and misoprostol, 400microg administered either vaginally or sublingually, are the most effective methods of cervical preparation.

Overcoming the challenging cervix: techniques to access the uterine cavity

OBJECTIVE

To identify cervical stenosis and review medical, surgical, and radiological modalities to access the uterine cavity.

MATERIALS AND METHODS

Computerized searches of Medline and PubMed from 1996 to 2005 were conducted using the key words "cervix," "cervical ripening," and "cervical stenosis." References from identified publications were manually searched and cross-referenced to identify additional relevant articles. We review relevant techniques on how to access the uterine cavity when cervical stenosis is encountered.

RESULTS

Many gynecologic procedures require uncomplicated access through the cervix to access the uterine cavity, including hysteroscopy, dilation and curettage, sonohysterogram, hysterosalpingogram, endometrial biopsy, and embryo transfer for in vitro fertilization. These procedures can be quite complicated when a cervix is obstructed. Management techniques described include the medical use of misoprostol and laminaria, intraoperative ultrasound guidance, and operative creation of a new passage. Additionally, techniques for bypassing the obstructed cervix and preventing cervical stenosis have been described.

CONCLUSIONS

Cervical stenosis can result in iatrogenic complications. Preoperative identification, cervical ripening agents, osmotic dilators, and the use of ultrasound guidance are useful in overcoming cervical stenosis. It is also key to identify those at risk for cervical stenosis and implement preventative techniques as needed.

Mifepristone does not induce cervical softening in non-pregnant women

BACKGROUND

Many techniques have been developed to soften the cervix to reduce complications following surgical dilatation. Progesterone inhibits myometrial contractility and its secretion during pregnancy ensures cervical competence. We used the progesterone antagonist mifepristone as a cervical ripening agent and evaluated its effect prior to office hysteroscopy.

METHODS

Fifty-eight healthy non-pregnant women aged 18-50 were studied in a randomized double-blind study. They received mifepristone (200 mg) or placebo 30 h prior to hysteroscopy. A Hegar test was performed prior to drug administration and again before hysteroscopy. A visual analogue pain scale was used to assess pain.

RESULTS

Medical history, physical examination and blood tests were similar in both groups, except for serum progesterone which was higher in the study group. Hegar measurement prior to drug ingestion was similar in both groups and after a mean time of 30.3 h increased in both groups. Neither the DeltaHegar measurement nor the pain scale was different in the two groups. There was also no effect of the high progesterone levels.

CONCLUSIONS

Unlike its dramatic effect in the pregnant uterus, mifepristone administered 30 h prior to hysteroscopy was not effective in ripening the cervix of non-pregnant women.

An antiprogesterone, onapristone, enhances the gene expression of promatrix metalloproteinase 3/prostromelysin-1 in the uterine cervix of pregnant rabbit

Using a progesterone receptor antagonist, onapristone/ZK 98.299, we examined the in-vivo effects of progesterone on the function of uterine cervix during pregnancy. Onapristone was intravenously administered to pregnant rabbits on day 20 post coitum. After 24 h, the antiprogesterone increased the wet weight of the uterine cervix and decreased the DNA concentration in the cervix. In-situ hybridization also indicated that antiprogesterone augmented the expression of matrix metalloproteinase (MMP)-3/stromelysin-1 mRNA in the uterine cervix. These changes are very similar to those observed and reported thus far in ripened and dilated uterine cervix. These results suggest that during pregnancy, progesterone closely participates in the maintenance of the function of uterine cervix by preventing the production of MMPs and thereby destruction of extracellular matrix, and thus add support to the theory that antiprogesterone has the potential to accelerate for the uterine cervical ripening and dilatation.

Mifepristone (RU486): a review

OBJECTIVE

To review the literature concerning the mechanism of action and pharmacodynamics of mifepristone (RU486), potential new uses of RU486, and its current use not only as an abortifacient but also as therapy for endometriosis, leiomyoma, breast cancer, and meningioma.

DATA IDENTIFICATION AND SELECTION

Studies that relate to RU486 were identified through a MEDLINE search.

CONCLUSION(S)

RU486 is an 11 beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. The receptor binding is not followed by transcription of P-dependent genes. Mifepristone effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. In addition, it has been used in the treatment of leiomyomata, endometriosis, advanced breast cancer, and meningioma. It is a powerful tool to study the molecular action of P and in the future may be used as an estrogen-free contraceptive.

Influence of an antiprogestin (onapristone) on in vivo and in vitro fertilization

The effects of a progesterone antagonist (onapristone) on heat synchronization, luteinizing hormone (LH) surge, ovulation, oocyte maturation and fertilization of superovulated ewes were studied. Its effects on in vitro bovine oocyte maturation and fertilization were also studied. Estrus synchronization and superovulation treatments were applied to 39 adult ewes using an intravaginal sponge with fluorgestone acetate for 9 days with injections of prostaglandin F2 alpha and pregnant mare's serum gonadotrophin given 24 h before sponge withdrawal. The animals were randomly assigned to four different groups; T1 receiving only the synchrony treatment (n = 11); T2 ewes received two injections of onapristone (1 mg kg-1, i.v.) 12 h apart from 3 h after sponge withdrawal (n = 10); T3 ewes received two injections of progesterone 12 h apart from sponge withdrawal (n = 10); and, T4 ewes received both onapristone and progesterone as described (n = 8). Ewes were mated by a fertile male during estrus. Progesterone and LH were measured during the superovulation period in plasma samples taken every 4 h. Uterine flushings for ova recovery were performed at 5 days (n = 25), 48 h (n = 5) and 24 h (n = 5). Non-fertilized oocytes collected at 24 and 48 h were checked for meiosis resumption. The effects of two doses of onapristone (D1 and D2) on in vitro bovine oocyte maturation (control = 100, D1 = 100 and D2 = 100) and fertilization (control = 107, D1 = 40 and D2 = 75) were also studied. The percentage of animals showing heat signs was significantly lower in group T3 (50% vs. 100%). The onset of oestrus (27.6, 24.8, 68.8 and 25.5 h, respectively for T1, T2, T3 and T4) and an LH surge (32.3, 28.8, 76.5 and 30.5 h, respectively for T1, T2, T3 and T4) after sponge withdrawal were significantly delayed in group T3. There were no significant differences in the intervals between estrus and LH surge among groups (4.61 +/- 0.75 h). The response and ovulation rates until 40 h after sponge withdrawal (group T3 excluded) were similar among groups, but the fertilization rates were significantly lower in groups T2 and T4 when compared with T1 (2% and 3% vs. 41%, respectively; P < 0.001) due to sperm arrest in the cervix. Ova recovery rate decreased significantly from 24-48 h to 5 days and was not affected by treatments (76.9% vs. 37.1% respectively). Onapristone did not affect the resumption of meiosis. Fertilization of bovine oocytes in vitro decreased significantly only in group D2 when compared to control (48% vs. 62.6%, respectively). In conclusion, onapristone treatment during the preovulatory period did not interfere with normal synchronization of estrus, ovulation and oocyte maturation but severely compromised fertilization by arresting spermatozoa in the cervix.

A series of 1000 consecutive out-patient diagnostic hysteroscopies

OBJECTIVE

To review the success of out-patient diagnostic hysteroscopy.

METHOD

Retrospective review of 1000 consecutive out-patient hysteroscopies.

RESULTS

Hysteroscopy was successfully performed in 96%. Cervical dilatation was required in 15.0% and local anaesthesia was administered in 31.4%; 77.3% of those requiring cervical dilatation received local anaesthesia. Intrauterine pathology was noted in 49.3%. The procedure failed in 40 (4%) patients for the following reasons: pain or anxiety in 23, cervical stenosis in 11, equipment failure in 4, and extreme uterine retroversion and inadvertent false cavity formation in one case each.

CONCLUSION

Out-patient diagnostic hysteroscopy is a safe, well tolerated and successful investigation procedure in the majority of patients and should be the procedure of choice for suspected intrauterine pathology.

Effects of mifepristone and progesterone on collagen synthesis in the human uterine cervix

Antiprogestins are used to induce first trimester abortion and to dilate the cervix before vacuum aspiration. Cervical dilatation is associated with profound changes in the connective tissue. In what respect antiprogestins interfere with this process has hitherto been sparsely investigated. The aim of present study was to examine the influence of the antiprogestin mifepristone on cervical collagen synthesis in nonpregnant, early and late pregnant women. The effects were compared with those of progesterone. The content of collagen in cervical tissue was determined by measuring hydroxyproline. Collagen synthesis was studied in vitro either by incubation of cervical tissue specimens from women, pretreated with mifepristone in vivo, in the presence of 14C-proline or by incubation of cervical tissue of not pretreated women in the presence of the isotope and mifepristone or progesterone. Pretreatment with mifepristone, but not progesterone, induced a significant increase in cervical dilatation. The cervical concentration of collagen was not altered after mifepristone administration. Pretreatment with mifepristone did not quantitatively influence the time course of radiolabeling in vitro or the pattern of radiolabeling in different protein components as revealed by electrophoresis. In vitro mifepristone, like progesterone, reduced the incorporation of 14C-proline. From the present data we conclude that mifepristone pretreatment in connection with first trimester abortion is not associated with any major changes, qualitatively or quantitatively, of collagen synthesis. However, we cannot exclude that mifepristone still may affect the de novo formation of collagen since mifepristone, administered in vitro, did reduce collagen synthesis.

Suppression of interleukin 8 production by progesterone in rabbit uterine cervix

Uterine cervical fibroblasts prepared from rabbits at 23 days of gestation were found to produce spontaneously the neutrophil chemotactic factor/interleukin 8 (IL-8). When the cells were treated with recombinant human interleukin 1 alpha and 1 beta (rhIL-1 alpha and -1 beta), both cytokines similarly enhanced the production of IL-8 in a dose-dependent manner. Recombinant tumour necrosis factor alpha also enhanced its production to a lesser extent, but interleukin 6 failed to modulate the production. Physiological concentrations of progesterone suppressed both the spontaneous and IL-1-mediated production of IL-8 in parallel with the decrease in the steady-state levels of its mRNA. These suppressive actions of progesterone were offset by co-treatment of cells with a progesterone antagonist, mifepristone (RU486). In conclusion, basal and IL-1-induced IL-8 production in rabbit uterine cervical fibroblasts is down-regulated by progesterone at the transcriptional level. These results obtained in vitro and our previous observations indicating that progesterone modulates the extra-cellular matrix breakdown via the suppression of production of matrix metalloproteinases and the augmentation of production matrix metalloproteinases and the augmentation of production of their specific inhibitors (TIMP-1) [Sato, Ito, Mori, Yamashita, Hayakawa and Nagase (1991) Biochem. J. 275, 645-650] may explain the mechanisms of the maintenance of pregnancy until parturition and the acceleration of uterine cervical ripening and dilatation at term.

Dose-response relationships of RU 486

Clinical experience has indicated that the effects of RU 486 can be divided into dose-dependent and dose-independent effects. Examples of the dose-dependent effects include the antiglucocorticoid effects of RU 486, whereas pregnancy termination or dilatation of the cervix can be considered dose-independent with the various regimens tested so far. Following oral intake in man, the serum levels of RU 486 are in the micromolar range, and the half-life is approximately 30 hours. The concentrations of RU 486 in myometrial tissue are approximately one-third of those measured in serum. However, due to saturation of alpha 1-acid glycoprotein (AAG), the serum binding protein for RU 486, the serum levels remain similar within the dose range of 100-800 mg of RU 486. The unbound RU 486 is metabolized by two-step demethylation or by hydroxylation. The demethylated and hydroxylated metabolites of RU 486 retain considerable affinities of 9-21% towards the human progesterone receptor, and 45-61% towards the human glucocorticoid receptor (RU 486 = 100%), suggesting a biological role for the metabolites. Rat serum lacks a specific binding protein for RU 486. Even though the levels of RU 486 in rat adipose tissue are 40 times as high as those seen in serum, the concentrations of RU 486 in rat brain are only 28% of the serum levels. This indicates that diffusion of RU 486 into the central nervous system is restricted by the blood-brain barrier. Hence, the dose-dependency of certain centrally mediated effects of RU 486 might be explained by the limited diffusion of RU 486 into hypothalamic/hypophyseal sites, which seem to be reached only after ingestion of high doses of RU 486. However, the peripheral effects of RU 486, such as termination of pregnancy, are mediated via steroid receptors in target tissues. This suggests that similar biological effects can be attained at considerably lower doses than the ones currently in use.

Prostaglandins and the cervix

The dramatic capabilities of prostaglandins to modify the condition of the uterine cervix have been exploited to the considerable benefit of patients who require therapeutic interventions for labour induction and termination of pregnancy. This will continue to be an important facet of clinical obstetric and gynaecologic practice, although further refinements and improvements in techniques seem certain to continue.

Randomised comparative study in 217 women of three disposable plastic IUCD thread retrievers

OBJECTIVE

To assess the relative efficacy of three disposable plastic instruments in the retrieval of 'missing' IUCD threads.

DESIGN

A prospective randomised comparative single centre study.

SETTING

Family Planning Clinic in London, UK.

SUBJECTS

217 of 350 IUCD users referred to the research team with 'missing' IUCD threads entered the study.

INTERVENTION

All women initially underwent exploration of the endocervical canal with Spencer Wells forceps. When this procedure did not retrieve the threads, the patients were entered into the study. A maximum of two randomly chosen plastic IUCD thread retrievers were then used in any one patient to explore the uterine cavity and capture the 'missing' threads. The order in which the two retrievers were employed was also determined at random. Four separate entries into the uterine cavity were permitted with each instrument, the endocervical canal being explored with Spencer Wells forceps after each retraction of the instrument to identify the possible descent of the threads.

MAIN OUTCOME MEASURES

Threads brought down beyond the external cervical os, or threads brought to within the endocervical canal and then grasped by Spencer Wells forceps.

RESULTS

In approximately 40% of all patients, the threads were retrieved with Spencer Wells forceps alone and a further 40% with the disposable plastic retrievers. About 5% had no retrievable threads, and only 2.5% of the referred patients required general anaesthesia for removal of their IUCD. The analysis of the comparative trial was confined to the 197 patients with retrievable threads which could not be brought below the external os with Spencer Wells forceps. The first plastic retriever used was successful in 50% of patients. The Retrievette (59%) and the Emmett (53%) performed better than the Mi-Mark Helix (37%) in this study. The difference was statistically significant (P = 0.03) and the 95% confidence interval for the difference of the Mi-Mark Helix from the other two retrievers was 4% to 33%. This retrieval rate for the Mi-Mark Helix was much worse than in previously reported studies, though one doctor did have a better success rate with this retriever. The success rates, using a second plastic retriever randomly chosen from the two not used in the first attempt, were almost identical to those observed with the first retrievers: 63%, 56% and 36%. The success rate did not appear to be influenced by the length of thread, day of cycle, device type or parity. The success of the second retriever tried did not seem to be influenced by the retriever that had failed previously.

CONCLUSIONS

Based on our experience, the initial exploration of the endocervical canal with Spencer Wells forceps is invaluable. If this simple manoeuvre fails to retrieve the 'missing' threads, either the Retrievette or the Emmett thread retrievers are useful tools in general practice or in the family planning clinic setting.

Should we use prostaglandins, tents or progesterone antagonists for cervical ripening before first trimester abortion?

Sixty-four women requesting first trimester termination of pregnancy were recruited into a comparative cohort study comparing the cervical ripening properties of a mechanical dilator (Lamicel; n = 17), prostaglandin, antiprogesterone and placebo control (n = 15), gemeprost; n = 17) and mifepristone; n = 15). Compared to the placebo group, all 3 active agents dilated the cervix (p < 0.02) and they significantly reduced the force required to dilate it to 8 mm Hegar (p < 0.001). Although Lamicel insertion resulted in the largest pre-operative cervical dilatation all agents are effective. Therefore the cervical priming agent of choice should be the most convenient to use and the one with least side-effects. The oral antiprogesterone, Mifepristone, is the easiest to administer and has less side effects.

Cervical softening with mifepristone (RU 486) after pretreatment with naproxen. A double-blind randomized study

Pretreatment with the progesterone antagonist mifepristone reduces the stiffness and facilitates mechanical dilatation of the uterine cervix. We studied the influence of the cyclo-oxygenase inhibitor naproxen on the softening effect of mifepristone on the cervix in thirty nulliparae. The patients were randomly allocated to receive 500 mg naproxen (group A) or placebo (group B) orally 60, 48, 36, 24 and 12 hours prior to vacuum aspiration. All patients received 100 mg mifepristone 48 and 36 hours before surgery. We found that the cervical softening effect of mifepristone was not antagonized by naproxen. The study indicates that the effect of mifepristone on the early pregnant cervix is not mediated through an increased production of prostaglandins.

Pretreatment of the primigravid uterine cervix with mifepristone 30 h prior to termination of pregnancy: a double blind study

OBJECTIVE

To determine the effect of the antiprogestogen mifepristone (RU 486) on cervical resistance before first trimester termination of pregnancy.

DESIGN

Prospective double blind randomized placebo controlled study.

SETTING

Department of gynaecology in a university teaching hospital, Sheffield.

SUBJECTS

80 Primigravid women greater than 18 years of age, undergoing termination of pregnancy at between 7 and 13 weeks gestation.

INTERVENTIONS

A single dose of 600 mg of mifepristone or placebo given orally 30 h before termination of pregnancy under general anaesthesia.

MAIN OUTCOME MEASURES

Cervical resistance to dilatation.

RESULTS

Pretreatment with mifepristone significantly reduced the amount of force required to dilate the cervix to 10 mm. In comparison with placebo, the mean sum of the peak forces obtained with dilators 4 to 10 mm was reduced from 84.3 N (SD 29.7) to 46.0 N (SD 26.7). Two women in the treated group had a cervical resistance of greater than 100 N compared with nine women in the placebo group (RR 0.18, 95% CI 0.04-0.89). The 8 mm dilator could be passed with less than 5 N force in 16 women (43%) in the treated group compared with none in the placebo group. Women in the active treatment group had more preoperative pelvic pain and vaginal bleeding but less postoperative pain.

CONCLUSION

Mifepristone significantly reduces cervical resistance in the first trimester of pregnancy and produces minimal side effects.