Prostaglandin E and F2 alpha concentration in the cervical mucus and mechanism of cervical ripening.

OBJECTIVE: To study the mechanism of cervical ripening by determination of prostaglandin E (PGE) and F2 alpha (PGF2 alpha) concentrations in cervical mucus during the course of pregnancy. STUDY DESIGN: Cervical mucus was collected from 99 pregnant women attending the mother care unit of the department. Women with sexual intercourse within the last 24 hours before sampling and subjects with bacterial vaginosis were analysed separately. RESULTS: Eleven women had sexual intercourse within 24 hours before sampling. The concentration of PGE in their cervical mucus was high corresponding to 2000-4000 pg/mg w w lasting for a period of 10-12 hours postcoitally, whereas the levels of PGF 2 alpha only increased slightly. Bacterial vaginosis was accomplished by a slight but significant elevation of PGF2 alpha levels but only of a minor increment of the PGE values. The prostaglandin concentrations in the mucus from the remaining 68 women were for PGE 102.75 +/- 111.51 and for PGF2 alpha 97.54 +/- 82.48 pg/mg w w (mean +/- SD). Although the values were scattered the concentrations remained at approximately the same level throughout pregnancy and there was no tendency towards an increment during the last weeks of pregnancy when cervical maturation is apparent. CONCLUSION: Cervical softening seems not to be accomplished by a massive local release of prostaglandins but rather the result of a number of different mechanisms more or less influenced by minor alterations of prostaglandin synthesis and release. Involved in these mechanisms are probably neutrophil-derived collagenases.

Prostaglandin release from human cervical tissue in the first trimester of pregnancy after preoperative dilatation with hygroscopic tents.

Preoperative dilatation with hygroscopic tents before first trimester abortion by vacuum aspiration is widely accepted and reduces the risk of early and late complications. A softening effect and a reduced compliance to mechanical dilatation occurs in addition to pure mechanical dilatation of the cervix. If this softening is an effect of local prostaglandin release, however, is unknown. Prostaglandin (PG) release in vitro from cervical biopsies following dilatation in vivo by a synthetic hygroscopic tent (Dilapan) for periods of 4 h and 18 h was compared with that of biopsies from untreated women. No difference was observed between the release of PGE2, PGF2 alpha, or 6-keto-PGF1 alpha. No significant difference was found in the tissue water content between treated and untreated women (83.8% versus 83.2%). Prostaglandins were also extracted from an alternative cervical dilator, Lamicel (a polyvinyl sponge impregnated with magnesium sulfate), and compared with the corresponding values from women pretreated with the cyclooxygenase inhibitor indomethacin before application of the tent. Significantly higher concentrations of PGE2 and PGF2 alpha but not of 6-keto-PGF1 alpha were found in women who had not been indomethacin-treated compared with indomethacin-treated women. Slices of the cervix from non-pregnant women operated upon for benign conditions were divided into an outer stromal layer and an inner layer, including the mucosa, and the PG-release in vitro was measured. The inner layer of the cervix showed a significantly higher release of PGE2 and PGF2 alpha compared with the outer layer. Lamicel treatment before first trimester abortion results in a significant dilatation of the cervix and a reduced compliance to mechanical dilatation, and this study supports the hypothesis that this effect is mediated via a local PG-release from the cervix. It seems reasonable to believe that Dilapan treatment too has the capacity to induce PG-release from the cervix, but this could not be demonstrated in this study, probably because needle biopsies taken mainly from the outer cervical layers were analyzed.

Cervical mucus concentration of prostaglandins E2 and F2 alpha after pretreatment with mifepristone in the first trimester of pregnancy.

Cervical dilatation and softening after pretreatment with mifepristone are well documented. As this effect is similar to that observed after local application of prostaglandin E2 (PGE2) it is tempting to speculate that the effect of mifepristone is mediated via an increase of the endogenous secretion of prostaglandins from the cervical mucosa. Eighteen healthy women in the first trimester of pregnancy were treated with oral mifepristone (200 mg) 48 and 24 hours before legal abortion by vacuum aspiration and 18 women in the same age of gestation without any pretreatment served as controls. Cervical mucus was collected for measurement of prostaglandins by radioimmunoassay before administration of the drug and in connection with vacuum aspiration. The cervical dilatation at the time of surgery was significantly increased in women given mifepristone as compared with untreated women (7.6 versus 5.8 mm). The wet weight of collected cervical mucus was significantly increased in mifepristone treated women. The amount of PGE2 and prostaglandin F2 alpha per sample was unchanged in mifepristone-treated women, whereas the concentration was lower as an effect of dilution due to an increased yield in cervical secretion observed after mifepristone treatment. The present observation does not give any support to the hypothesis that mifepristone-induced cervical maturation is mediated via an increase in cervical prostaglandin production.

Detection of bacterial vaginosis in wet mount, Papanicolaou stained vaginal smears and in gram stained smears.

In a prospective study of 107 women, bacterial vaginosis was clinically diagnosed in 34 women. Compared with clinical diagnosis of bacterial vaginosis, detection of clue cells in Papanicolaou stained vaginal smears showed a sensitivity of 88.2%, a specificity of 98.6%, a positive predictive value of 96.8% and a negative predictive value of 94.7%. The corresponding values for detection of bacterial vaginosis in Gram stained smears compared with the clinical diagnosis were 100%, 97.3%, 94.4% and 100%, respectively. Compared with clue cells in wet smears, identification of clue cells in Papanicolaou stained vaginal smears showed a Kappa index of 0.87 and compared with Gram stain criteria a Kappa index of 0.94. The correlation between Gram stain and Papanicolaou stained vaginal smears showed a Kappa index of 0.89. In contrast to the results of earlier investigators our studies indicate that the demonstration of clue cells in Papanicolaou stained vaginal smears correlate reasonably well with the conventional clinical criteria. However, the Gram stain method may be more reliable than the Papanicolaou method.

Endotoxin and interleukin-1 alpha in the cervical mucus and vaginal fluid of pregnant women with bacterial vaginosis.

OBJECTIVE: The purpose of our study was to determine the concentrations of endotoxin and interleukin-1 alpha in the cervical mucus and vaginal fluid of pregnant women who either did or did not have bacterial vaginosis. STUDY DESIGN: Samples of cervical mucus and vaginal fluid were collected from women in early pregnancy who had signs of bacterial vaginosis and from healthy control subjects. The samples were analyzed for the concentrations of endotoxin and interleukin-1 alpha. In addition, wet mounts were examined for signs of inflammation indicated by increased numbers of leukocytes. RESULTS: Both endotoxin and interleukin-1 alpha occurred in much higher concentrations (p < 0.0001, p < 0.0002) in both the cervical mucus and the vaginal fluid of women with signs of bacterial vaginosis than they did in healthy control subjects. A correlation was found between the interleukin-1 alpha concentrations in the vaginal fluid and the number of leukocytes as judged by a semi-quantitative evaluation of wet mounts (p = 0.0365). The concentrations of endotoxin correlated with those of interleukin-1 alpha in both fluids (vaginal fluid, p < 0.01; cervical mucus, p < 0.01). CONCLUSION: Our study shows that concentrations of endotoxin and interleukin-1 alpha in cervical mucus and vaginal fluid of women in early pregnancy who have bacterial vaginosis are significantly higher than the corresponding levels in control subjects.

A longitudinal follow-up of bacterial vaginosis during pregnancy.

Bacterial vaginosis (BV) has been considered by many investigators to be a risk factor for preterm labor. We have followed vaginal pH and the persistence of clue cells in Papanicolaou stained smears in 119 pregnant women during the course of pregnancy. Of 19 patients with clue cells in their smears during the first trimester, 11 (58%) still had clue cells at the second visit during the third trimester. Of the 100 patients without clue cells during their first trimester, none exhibited clue cells during the third trimester. If the persistence of clue cells is truly a risk factor for adverse pregnancy outcome, screening in the first trimester would identify a risk group of 15%. This risk group diminishes to 9% at the time of the third trimester. Vaginal pH > 4.5 had a recovery sensitivity of 76% and specificity of 83%. If clue cells can be considered as the identifying standard for bacterial vaginosis, the sensitivity and specificity of pH is 89% and 94%, respectively. The establishment of the diagnosis of BV during pregnancy and, in some cases, the treatment of the condition may be important as routine procedures in the antenatal center.

Increased prostaglandin concentrations in the cervical mucus of pregnant women with bacterial vaginosis.

Microorganisms associated with bacterial vaginosis are commonly recovered from the amniotic fluid and chorion-amnion of patients who deliver prematurely. Bacteria closely related to those causing bacterial vaginosis may play a role in the initiation of uterine contractions, ripening of the cervix and weakening of the fetal membranes by stimulating prostaglandin synthesis. In the present investigation, cervical mucus was collected by brush from early pregnant women with and without bacterial vaginosis. The concentrations of PGE2, PGF2 alpha and 6-keto-PGF1 alpha were determined in the mucus samples by methyl oximation and then radioimmunoassay, utilizing antibodies raised against oximated prostaglandins. It was found that the concentration of PGE2 and PGF2 alpha was significantly higher in the mucus of women with bacterial vaginosis compared with healthy women. The concentration of 6-keto-PGF1 alpha was similar in both study groups. All patients had been instructed to abstain from sexual intercourse for 24 hours before sampling. However, it may be that women with high concentrations in their mucus may have had intercourse anyway. However, it is fairly well possible that the significant differences in the PGE2 and PGF2 alpha values are causally related to the higher rate of preterm labor in women with the commonplace infection of bacterial vaginosis.

Preoperative dilatation of the cervix at legal abortion with a synthetic, fast-swelling hygroscopic tent.

Preoperative dilatation of the cervix at first trimester legal abortion has been shown to facilitate the vacuum aspiration procedure and to reduce per- and postoperative complications as well as late sequelae. The present study represents a clinical trial in which a new synthetic hygroscopic tent, Dilapan, has been evaluated. Dilapan tents of different diameters with different durations of cervical exposure were tested on a case material of 450 nulliparous women. It was found that treatment with 4 mm tents during 3-4 h or 3 mm tents during 16-20 h produced a cervical dilatation that allowed an easy evacuation of the uterus with a minimum of complications. The advantage of this particular tent is its property of rapid swelling.

Induction of labor by intra-cervical PGE2 in viscous gel. Mechanism of action and clinical treatment routines.

Induction of labor in women with immature cervix was accomplished by four different treatment schedules. The case material included a total of 100 subjects, each treatment group having 25 cases: Group A: Intravenous oxytocin; Group B: Intracervical PGE2-gel followed by intravenous oxytocin; Group C: Intracervical PGE2-gel twice with a 12-hour interval; Group D: Intracervical placebo gel twice with 12-hour interval. Oxytocin did not influence the Bishop score (B.S.) unless in the presence of active labor contractions. In contrast, there was an increment in B.S. by 3.6 points on average within 12 hours following PGE2-gel as calculated from data of subjects without signs of contractions. These results support the concept of a local action of PGE2-gel. The increment in B.S. was larger in subjects with very immature cervices (B.S. less than or equal to 2) than in those with moderately immature scores (B.S. 4). A second PGE2-gel instillation did not increase the B.S. above the level achieved by the first application, indicating that pharmacological ripening of the cervix by a single dose of PGE2 results in an effect approaching maximum. The success rate was the same for oxytocin and PGE2-gel treated women during the first 24 hours, when approximately 40% of the women had given birth. The oxytocin group remained at that level of success rate, whereas the PGE2-gel-oxytocin and PGE2-gel X 2 series continued to improve their success rate up to 75%. An interesting finding in the study was that women given PGE2-gel twice did not need intravenous oxytocin stimulation except in a few cases.

Leukotrienes and myometrial activity of the term pregnant uterus.

Biopsies from different segments of the pregnant human uterus were superfused in organ chambers and contractile activity was registered. Leukotriene C4(LTC4) caused inhibition of spontaneous but not noradrenaline induced contractile activity in strips from the cervix. This effect occurred both in early pregnancy and at term. However, the lower and the upper uterine segment of the term pregnant uterus did not respond to LTC4. The results represent a documentation of the segmental differentiation in the uterine response to eicosanoids.

The role of prostaglandins for the coordination of myometrial forces during labour.

Systematic studies using a superfusion technique for recording myometrial contractility in vitro have been conducted in our department to explore whether prostaglandins (PG) have a differential action on the different segments of the pregnant uterus and also whether the qualitative and quantitative response undergoes a change during spontaneous labour. Myometrial specimens were excised from the fundal area and from the lower uterine segment at elective caesarean section in the 39th week of pregnancy before commencement of labour and at acute caesarean section during ongoing labour. Before labour PGF2 alpha was without or had a very weak effect on upper segment preparations but was stimulatory on lower segment specimens. PGE2 and PGI2 generally induced a biphasic dose-dependent response (stimulation followed by inhibition). During spontaneous labour PGF2 alpha and PGE2 always stimulated upper segment preparations while the contractile activity of specimens from the lower segment was inhibited by PGE2, PGF2 alpha was generally without effect. PGI2 had the same biphasic action before as during labour. With all reservations for the validity of in vitro experiments, the results favour the hypothesis that initiation of labour in the human involves a qualitative shift in the myometrial reactivity to prostaglandins. These alterations may involve suppression of expulsive forces and perhaps some tightening of the lower uterine segment during pregnancy. Following initiation of labour there is a marked increase in the excitatory action of both PGE2 and PGF2 alpha in the fundal area while the lower uterine segment reacts in a way that favours dilatation.

Oxytocin and cervical connective tissue.

The effect of oxytocin on collagen synthesis in the pregnant human cervix and lower uterine segment was studied in incubation experiments by measuring the incorporation of 3H-proline. Oxytocin had a concentration related inhibitory effect on the labelling with 3H-proline. Vasopressin in the corresponding concentrations had only a weak effect on the incorporation of 3H-proline. Addition of indomethacin did not influence the response to oxytocin indicating that the effect was probably not mediated by prostaglandins. These results suggest that oxytocin under in vitro experimental conditions influences cervical connective tissue metabolism which is in contrast to current clinical experience.

Catecholamines and contractility of the human myometrium at term: a possible role for prostaglandins.

The contractile response of small myometrial specimens from the term pregnant human uterus was investigated using a superfusion technique. Adrenaline, noradrenaline and dopamine all had a stimulatory effect on the contractility. It was also demonstrated that this stimulatory effect was alpha-adrenoceptor mediated. If the tissue was pretreated with the prostaglandin synthetase inhibitor indomethacin or the arachidonic acid analogue eicosa-5,8,11,14-tetraenoic acid the effect of catecholamines was significantly reduced. This suggests a specific role of prostaglandins in the mechanism of action of catecholamines on the human myometrium.

Inhibitory action of relaxin on human cervical smooth muscle.

The influence of purified porcine relaxin on contractility of human cervical smooth muscle was investigated in vitro. Strips of cervical tissue were obtained by needle biopsy from pregnant and nonpregnant women and were mounted in a superfused organ chamber for isometric measurement of contractile activity. Relaxin (0.005-25 micrograms/ml) inhibited the spontaneous contractions in cervical strips from 18% of nonpregnant, 68% of early pregnant, and in 100% of term pregnant women. These results indicate that relaxin has an inhibitory action on cervical smooth muscle and that this effect is more constantly detected as pregnancy proceeds.

Effects of oxytocin on cervical and uterine connective tissue.

The effect of oxytocin on collagen metabolism in the cervix and lower uterine segment of pregnant women was studied by measuring the incorporation of [3H]proline in vitro. Oxytocin had a concentration related inhibitory effect on the labelling with [3H]proline. Addition of indomethacin did not influence the response to oxytocin indicating that the effect was not directly mediated by prostaglandins. Oestradiol-17 beta potentiated the effect of oxytocin. Vasopressin decreased the incorporation of [3H]proline slightly but the action of this hormone was significantly less than that of oxytocin. The results suggest that oxytocin under in vitro experimental conditions influences cervical connective tissue metabolism which is in contrast to current clinical experiences.

Regulatory influence of relaxin on human cervical and uterine connective tissue.

Cervical tissue was obtained from women undergoing legal abortion in the 7th-15th week of gestation and tissue from the lower uterine segment was excised at elective Casearean section in the 38th-40th week. The specimens were incubated with [3H]proline in the presence of relaxin or prostaglandin E2 (PGE2). Relaxin had a concentration related inhibitory effect on the radiolabelling in the 7th-9th week but failed to influence the amino acid uptake in the 10th-15th week of pregnancy. PGE2 had the inverse effect, i.e. no influence in the former group but reduced incorporation of proline in the latter group of patients. Incubation of tissue from the lower uterine segment showed a similar response as that of the early pregnant cervix. It is concluded that relaxin has a significant influence on [3H]proline incorporation by cervical and uterine tissue under in vitro experimental conditions.