Vaginal prostaglandins and labour induction for patients previously delivered by caesarean section

The history of labour induction: How did we get here?

The mean duration of human pregnancy is 280 days but the range is wide, and "term" has been defined to range from 37 to 42 weeks. In the 18th and 19th centuries, labour induction was used mainly in cases of pelvic deformity, before the foetus grew too large to be delivered. Induction methods were unreliable until the 20th century, when pituitary extract, and then synthetic oxytocin and prostaglandins, became available. "Disproportion" was the leading indication for induction until the 1950s, when it became clear that prolonged pregnancy was associated with increased perinatal mortality. Pregnancy dating was improved by ultrasound, which also showed that foetal growth slows at term. Induction rates rose during the 1970s, causing public concern about obstetric intervention. In the 21st century, large-scale randomised trials showed that perinatal mortality is lowest at 39-40 weeks, and that induction at that time does not increase the rate of operative delivery.

Prevalence of uterine rupture among women with one prior low transverse cesarean and women with unscarred uterus undergoing labor induction with PGE2: A systematic review and meta-analysis

BACKGROUND

As uterine rupture may affect as many as 11/1000 women with 1 prior cesarean birth and 5/10.000 women with unscarred uterus undergoing labor induction, we intended to estimate the prevalence of such rare outcome when PGE2 is used for cervical ripening and labor induction.

METHODS

We searched MEDLINE, ClinicalTrials.gov and the Cochrane library up to September 1st 2020. Retrospective and prospective cohort studies, as well as randomized controlled trials (RCTs) on singleton viable pregnancies receiving PGE2 for cervical ripening and labor induction were reviewed. Prevalence of uterine rupture was meta-analyzed with Freeman-Tukey double arcsine transformation among women with 1 prior low transverse cesarean section and women with unscarred uterus.

RESULTS

We reviewed 956 full text articles to include 69 studies. The pooled prevalence rate of uterine rupture is estimated to range between 2 and 9 out of 1000 women with 1 prior low transverse cesarean (5/1000; 95%CI 2-9/1000, 122/9000). The prevalence of uterine rupture among women with unscarred uterus is extremely low, reaching at most 0.7/100.000 (<1/100.000.000; 95%CI <1/100.000.000-0.7/100.000, 8/17.684).

CONCLUSIONS

Uterine rupture is a rare event during cervical ripening and labor induction with PGE2.

No. 155-Guidelines for Vaginal Birth After Previous Caesarean Birth

OBJECTIVE

To provide evidence-based guidelines for the provision of a trial of labour (TOL) after Caesarean section.

OUTCOME

Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean (VBAC) and repeat Caesarean section.

EVIDENCE

MEDLINE database was searched for articles published from January 1, 1995, to February 28, 2004, using the key words "vaginal birth after Caesarean (Cesarean) section." The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam.

RECOMMENDATIONS

VALIDATION: These guidelines were approved by the Clinical Practice Obstetrics and Executive Committees of the Society of Obstetricians and Gynaecologists of Canada.

Is it worth inducing labour in women with a previous caesarean delivery?

The aim of this study was to determine the outcome of labour induction following a previous caesarean section. A total of 43 cases were identified; 23 out of those (53.5%) achieved vaginal delivery. The remaining 20 cases (46.5%) had a repeat caesarean. A total of 25 women had ≥ 1 previous vaginal deliveries and in the remaining 18, the previous caesarean was the only pregnancy carried before the current pregnancy. Out of the 23 women who successfully delivered vaginally, 16 cases (69.6%) had a history of ≥ 1 previous vaginal delivery, while no such history was reported in the remaining seven cases (30.4%). The indications for a repeat caesarean were failed induction of labour in five cases (25%); fetal distress in seven cases (35%); failure-to-progress in eight cases (40%). Only one case (2.3%) of uterine rupture was reported. In conclusion, labour induction following a previous caesarean section is an effective and safe intervention. Vaginal delivery can be anticipated in the majority of these women. This study emphasises the need for thorough counselling of these women regarding benefits and risks of induction of labour, and also highlights the necessity of shared patient-doctor decision-making.

Delivery after caesarean section: consultant obstetricians' professional advice and personal preferences

The objective of this study was to determine how obstetricians would wish to be managed in their own pregnancy and their advice to patients delivering after a caesarean section. A questionnaire was sent to 219 consultant obstetricians in two large UK medical deaneries investigating their personal preferences for delivery and management of spontaneous, augmented and induced labour after a caesarean section and how they advise their patients related to the indication for the previous caesarean section. Responses were analysed according to age and gender. The questionnaire yielded a 68% response rate. None would counsel against labour unless there were contraindications. The majority would recommend labour for all indications for the previous caesarean section, although personal preferences were lower (p<0.04): 56% would recommend labour to their patients after a failed instrumental delivery, but only 36% would personally choose that option (p<0.002). Female obstetricians would contemplate and recommend labour more readily than males. Labour augmentation and induction was more frequently recommended (66% and 57%, respectively) than opted for personally (57% and 52%). Reluctance for labour augmentation and induction was greatest among younger consultants. While the majority of consultants favour labour for themselves and recommend this for their patients, it was reassuring to note that patients are encouraged to make the final decision. Informed patient choice is paramount and it is therefore important that full information about risks and benefits is available.

The influence of maternal request on the elective caesarean section rate

At a time when there is much criticism of increasing caesarean section rates, as well as an increased emphasis on involving the patient in decisions regarding her care, we decided to assess the effect of maternal request on the elective caesarean section rate. The study was a prospective patient interview and case note review, set at a District General Hospital in Watford, Hertfordshire over a 1-year period. Eligible patients included all women undergoing elective caesarean section, with the main outcome measure being the number of elective caesarean sections performed without obstetric contraindication to vaginal delivery. Out of 3025 deliveries, 570 (18.8%) were delivered by caesarean section, 276 (9.1%) electively and 293 (9.7%) as an emergency procedure. Of the elective procedures (18.2% of the total number of operations), 38% were performed because of maternal request. We conclude that maternal request is a significant factor in the rise in caesarean section rate.

The experience with prostaglandin E2 vaginal tablets for induction of labour in grand and great grand multiparae. A two year review in Saudi Arabia

In an attempt to review our experience with prostaglandin E2 vaginal tablets in induction of labour in grandmultiparae (parity 5-9) and great grandmultiparae (parity > 9) a retrospective study was carried out at King Faisal Military Hospital in Saudi Arabia over a 2-year period. An evaluation of our protocol for induction of labour using prostaglandin in these groups of patients was also made. The patients included 271 grandmultiparae and 63 great grandmultiparae. There were no serious side effects in our series referable to the prostaglandin induction. There were no significant differences in the two groups regarding the mean total dose of prostaglandin used, mean length of second stage of labour, mean birth weight and admission to the neonatal intensive care unit (P > 0.05). However, the need for syntocinon augmentation was more in the great grandmultiparae (29% vs. 19%) but this was not significant statistically (P = 0.64). The caesarean section rate was higher in the great grandmultiparae (14% vs.10%) but not statistically significant (P = 0.19). None of the babies in the study group had an Apgar score less than 7 at 5 minutes. This study has shown that it may be safe to use prostaglandin E2 vaginal tablets for induction of labour in grandmultiparae and great grandmultiparae in our environment although the sample size may not be large enough to draw definite conclusions. Our protocol of stepwise increase in prostaglandin dose did not increase maternal or fetal morbidity but might actually have reduced the number of caesarean sections performed and therefore maternal mortality associated with caesarean section in the grandmultiparae. A multicentre prospective trial is eagerly awaited.

Uterine rupture after induction of labour in women with previous caesarean section

BACKGROUND

The issues related to safety of induction of labour in women with previous caesarean section remain controversial. The main adverse outcome fuelling this debate is a "small" risk of uterine rupture that is potentially devastating for both the mother and the fetus.

OBJECTIVE

To estimate the risk of uterine rupture or dehiscence in women who require induction of labour with previous caesarean sections.

DESIGN

Five year retrospective review of computerised hospital records and case note review of index cases.

SETTING

Large inner city teaching hospital.

POPULATION

Two hundred and five women who had their labour induced with history of one lower segment caesarean section.

METHODS

This study was conducted at Liverpool Women's Hospital, a tertiary referral centre, with approximately 6000 births per annum. We searched the hospital's computerised records of deliveries from June 1997 to June 2002 and reviewed all indications and outcomes of induction of labour in women with one previous caesarean section. Women with singleton pregnancy and cephalic presentation were then divided into three groups: those with one previous caesarean section and no previous vaginal deliveries, those whose last delivery was a caesarean section but had delivered vaginally before and those whose last delivery was by vaginal route, but had had one caesarean section in the past.

MAIN OUTCOME MEASURES

Uterine rupture or dehiscence, adverse neonatal outcome.

RESULTS

Two hundred and five women were included. There were four cases of uterine rupture and one dehiscence (2.4%, 95% CI 0.8-5.6%). Two babies were profoundly acidotic at birth, but all five neonates were healthy when discharged from hospital with no long term morbidity. All five cases occurred in the group of women with no previous vaginal deliveries. The intrauterine pressure catheter recordings had contributed to the diagnosis of uterine rupture/dehiscence in three out of five cases.

CONCLUSION

In women with previous caesarean section and no vaginal deliveries, induction of labour carries a relatively high risk of uterine rupture/dehiscence despite all precautions, including intrauterine pressure monitoring.

Guidelines for Vaginal Birth After Previous Caesarean Birth

OBJECTIVE

To provide evidence-based guidelines for the provision of a trial of labour (TOL) after Caesarean section.

OUTCOME

Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean (VBAC) and repeat Caesarean section.

EVIDENCE

MEDLINE database was searched for articles published from January 1, 1995, to February 28, 2004, using the key words "vaginal birth after Caesarean (Cesarean) section". The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam.

RECOMMENDATIONS

1. Provided there are no contraindications, a woman with 1 previous transverse low-segment Caesarean section should be offered a trial of labour (TOL) with appropriate discussion of perinatal risks and benefits. The process of informed consent with appropriate documentation should be an important part of the birth plan in a woman with a previous Caesarean section (II-2B). 2. The intention of a woman undergoing a TOL after Caesarean section should be clearly stated, and documentation of the previous uterine scar should be clearly marked on the prenatal record (II-2B). 3. For a safe labour after Caesarean section, a woman should deliver in a hospital where a timely Caesarean section is possible. The woman and her health care provider must be aware of the hospital resources and the availability of obstetric, anesthetic, pediatric, and operating-room staff (II-2A). 4. Each hospital should have a written policy in place regarding the notification and (or) consultation for the physicians responsible for a possible timely Caesarean section (III-B). 5. In the case of a TOL after Caesarean, an approximate time frame of 30 minutes should be considered adequate in the set-up of an urgent laparotomy (III-C). 6. Continuous electronic monitoring of women attempting a TOL after Caesarean section is recommended (II-2A). 7. Suspected uterine rupture requires urgent attention and expedited laparotomy to attempt to decrease maternal and perinatal morbidity and mortality (II-2A). 8. Oxytocin augmentation is not contraindicated in women undergoing a TOL after Caesarean section (11-2A). 9. Medical induction of labour with oxytocin may be associated with an increased risk of uterine rupture and should be used carefully after appropriate counselling (II-2B). 10. Medical induction of labour with prostaglandin E2 (dinoprostone) is associated with an increased risk of uterine rupture and should not be used except in rare circumstances and after appropriate counselling (II-2B). 11. Prostaglandin E1 (misoprostol) is associated with a high risk of uterine rupture and should not be used as part of a TOL after Caesarean section (II-2A). 12. A foley catheter may be safely used to ripen the cervix in a woman planning a TOL after Caesarean section (II-2A). 13. The available data suggest that a trial of labour in women with more than 1 previous Caesarean section is likely to be successful but is associated with a higher risk of uterine rupture (II-2B). 14. Multiple gestation is not a contraindication to TOL after Caesarean section (II-2B). 15. Diabetes mellitus is not a contraindication to TOL after Caesarean section (II-2B). 16. Suspected fetal macrosomia is not a contraindication to TOL after Caesarean section (II-2B). 17. Women delivering within 18 to 24 months of a Caesarean section should be counselled about an increased risk of uterine rupture in labour (II-2B). 18. Postdatism is not a contraindication to TOL after Caesarean section (II-2B). 19. Every effort should be made to obtain the previous Caesarean section operative report to determine the type of uterine incision used. In situations where the scar is unknown, information concerning the circumstances of the delivery is helpful in determining the likelihood of a low transverse incision. If the likelihood of a low transverse incision is high, a TOL after Caesarean section can be offered (II-2B).

VALIDATION

These guidelines were approved by the Clinical Practice Obstetrics and Executive Committees of the Society of Obstetricians and Gynaecologists of Canada.

Our Experience with Vaginal Prostaglandin-E2 for Induction of Labor in Qatar: Six Months Review

In order to review our experience with prostaglandin-E2 for the induction of labour and to evaluate its safety and outcomesa retrospective study was carried out at the Women's Hospital, Hamad Medical Corporation, over a six-month period. Three hundred and thirty four patients (7% of total deliveries) were induced by PGE2 (Dinoprostone), including 105 (30%) nulliparae and 229 (70%) multiparae. Patients with a history of one previous lower segment caesarean section were also included. Post date pregnancy and diabetes were the most common indications for induction.

There were significant differences in the two groups regarding the number of doses and the mean total dose of PGE2 used. The need for syntocinon augmentation was more in the nulliparae (41% vs 22%). Failed induction occurred only in nulliparae. The rate of caesarean section in induced labour remained significantly low compared with a spontaneous labour (11.6% vs 10.7%). The caesarean section rate was higher in the nulliparae (16.0% vs 9.6%) but this was not statistically significant. The caesarean section rate was higher when Bishop score 0-4 (76% vs 24%). Only two of the babies in the study group had an Apgar score less than 7 at 5 minutes. There was one caesarean hysterectomy because of postpartum hemorrhage associated with the PGE2 induction.

Conclusion: The calculated induction rate with PGE2 was 7% of total deliveries. Induction of labour with PGE2 in a grandmultiparae and previous caesarean section is relatively safe but further multicentre studies are needed to confirm our findings.

Indications for caesarean section in a consultant obstetric unit over three decades

In this paper, we aimed to identify changes in the indications for and timing of caesarean section over 20 years. This involved a prospective data collection by clinical record analysis throughout the 12-month periods for 1976, 1986 and 1996. The study was carried out in the maternity unit of a large district teaching hospital. We studied all women delivered by caesarean section. Main outcome measures were rates for different indications for caesarean section for the populations served during each of the 3 years. Analysis of 1819 caesarean sections showed an increasing rate, from 6.7% in 1976 to 14.2% in 1996. The proportion of planned antepartum deliveries remained constant at 54%, with previous caesarean section given as the main indication in 1976 (55%) and 1986 (49%) and maternal request in 1996 (23%). Caesarean section for intrapartum fetal distress doubled over the study period, with little evidence of improved neonatal or long-term outcome. Caesarean section for failed labour induction and failed first- and second-stage progress all increased and for failed assisted delivery increased threefold. Caesarean section with a singleton breech presentation increased from 30% to 88% and for twin pregnancies from 13% to 47%. The rate of caesarean section for women delivered previously by section remained unaltered at 56%. The proportion of pregnancies delivered by caesarean section increased for virtually all indications. Consumer expectation has encouraged a more ready use of section, with maternal choice being the most frequent indication in 1996.

Cesarean section on demand

The safety of cesarean section has improved dramatically over the past 50 years. During the past 20 years a greater awareness of and discussion about the symptomatic morbidity that can result for women following vaginal delivery has occurred and women's expectations for the outcome of pregnancy for them and their babies has increased. A culture of choice has been promoted in recent years, but contrary to the anticipated demand for less obstetric intervention by those promoting choice, there has been an increase in demand for delivery by cesarean section rather than the reverse. With the balance in favor of benefit for the baby from delivery by cesarean section, it is now difficult to sustain the argument favoring vaginal delivery rather than planned cesarean section, using maternal morbidity and mortality statistics. A critical evaluation of the costs indicates that there are probably few grounds for denying women their request for cesarean section for economic reasons. It seems likely, therefore, that in the near future those advising women on the options for delivery will need to ensure that the risks of vaginal delivery are explained as well as those for planned cesarean section.

Uterine rupture

Uterine rupture is an uncommon obstetric event. It is important because it continues to be associated with maternal mortality, especially in developing countries, and with major maternal morbidity, particularly peripartum hysterectomy. It is also associated with a high incidence of perinatal mortality and morbidity worldwide. This chapter examines the incidence, aetiology, clinical presentation, complications and prevention of uterine rupture. The key factor in the cause of rupture is whether or not the uterus is scarred. Rupture of an unscarred uterus is rare, usually traumatic, and its incidence decreases with improvement in obstetric practice. Rupture of the scarred uterus is more common, and usually occurs after a trial of labour in a patient with a previous Caesarean section. This chapter also explores how the incidence and complications of uterine rupture may be minimized, and yet the incidence of vaginal birth after Caesarean section (VBAC) optimized, in clinical practice.

Risk factors for uterine rupture during a trial of labor after cesarean

The rate of vaginal birth among women with a previous cesarean increased from 18.9% in 1989 to 28.3% in 1996. By 1998, the rate had decreased to 26.3% and preliminary data from 1999 suggest that the rate for that year would be even lower (23.4%). It is not known whether that decrease represents a trend related to increasing concern by providers and women about the risk of uterine rupture. Whereas the overall risk of rupture is 1%, our review demonstrates that there is considerable variation of that risk. More than one previous scar, induction of labor, a short interdelivery interval, or a history of postpartum fever during a previous cesarean may increase the risk of a uterine rupture during a trial of labor. However, there does not appear to be an increase in risk associated with low-vertical scars, and a previous vaginal delivery may be somewhat protective. Further delineation of the factors that increase the risk of uterine rupture will permit better prediction of individualized risk and identification of women for whom attempting a vaginal delivery after cesarean represents a safe option.

Uterine rupture during induced or augmented labor in gravid women with one prior cesarean delivery

OBJECTIVE

Our purpose was to examine the risk of uterine rupture during induction or augmentation of labor in gravid women with 1 prior cesarean delivery.

STUDY DESIGN

The medical records of all gravid women with history of cesarean delivery who attempted a trial of labor during a 12-year period at a single center were reviewed. The current analysis was limited to women at term with 1 prior cesarean delivery and no other deliveries. The rate of uterine rupture in gravid women within that group undergoing induction was compared with that in spontaneously laboring women. The association of oxytocin induction, oxytocin augmentation, and use of prostaglandin E(2) gel with uterine rupture was determined. Logistic regression analysis was used to examine these associations, with control for confounding factors.

RESULTS

Of 2774 women in the analysis, 2214 had spontaneous onset of labor and 560 women had labor induced with oxytocin or prostaglandin E(2) gel. The overall rate of rupture among all patients with induction of labor was 2.3%, in comparison with 0.7% among women with spontaneous labor (P =.001). Among 1072 patients receiving oxytocin augmentation, the rate of uterine rupture was 1.0%, in comparison with 0.4% in nonaugmented, spontaneously laboring patients (P =.1). In a logistic regression model with control for birth weight, use of epidural, duration of labor, maternal age, year of delivery, and years since last birth, induction with oxytocin was associated with a 4.6-fold increased risk of uterine rupture compared with no oxytocin use (95% confidence interval, 1.5-14.1). In that model, augmentation with oxytocin was associated with an odds ratio of 2.3 (95% confidence interval, 0.8-7.0), and use of prostaglandin E(2) gel was associated with an odds ratio of 3.2 (95% confidence interval, 0.9-10.9). These differences were not statistically significant.

CONCLUSION

Induction of labor with oxytocin is associated with an increased rate of uterine rupture in gravid women with 1 prior uterine scar in comparison with the rate in spontaneously laboring women. Although the rate of uterine rupture was not statistically increased during oxytocin augmentation, use of oxytocin in such cases should proceed with caution.

Uterine rupture associated with the use of misoprostol in the gravid patient with a previous cesarean section

OBJECTIVE

Our purpose is to report our experience with uterine rupture in patients undergoing a trial of labor after previous cesarean delivery in which labor was induced with misoprostol. The literature on the use of misoprostol in the setting of previous cesarean section is reviewed.

STUDY DESIGN

This report was based on case reports, a computerized search of medical records, and literature review.

RESULTS

Uterine rupture occurred in 5 of 89 patients with previous cesarean delivery who had labor induced with misoprostol. The uterine rupture rate for patients attempting vaginal birth after cesarean section was significantly higher in those who received misoprostol, 5.6%, than in those who did not, 0.2% (1/423, P =.0001). Review of the literature reveals insufficient data to support the use of misoprostol in the patient with a previous cesarean delivery.

CONCLUSION

Misoprostol may increase the risk of uterine rupture in the patient with a scarred uterus. Carefully controlled studies of the risks and benefits of misoprostol are necessary before its widespread use in this setting.

Cervical ripening

Induction of labor is indicated when the benefits to either the mother or the fetus outweigh the benefits of continuing the pregnancy. The state of the cervix is clearly related to the success of labor induction and the duration of labor. In cases of unfavorable cervices, physicians usually use a ripening agent before inducing labor. Unfortunately, as reviewed in this article, the ideal ripening agent is not found yet. No method of cervical ripening has shown a consistent and significant reduction in CS rate. In fact, women with the most unfavorable cervices (Bishop score, < or = 2) still face high rates of induction failure and CS.

Vaginal delivery after Caesarean section: factors influencing success rates

In a retrospective review of 333 pregnancies in women who had 1 previous Caesarean section, 244 (73.3%) underwent a trial of scar, and 89 (26.7%) had an elective Caesarean section. In the trial of scar group 197 (80.7%) had a vaginal delivery and 47 (19.3%) required an emergency Caesarean section. The success of the trial was favourably influenced by a nonrecurring indication for the original Caesarean section, a previous vaginal delivery, and a smaller baby. Maternal morbidity was greater in the groups requiring a Caesarean section, whether elective or emergency. Those patients delivered vaginally spent significantly less time in hospital. In 2 of the 244 patients (0.8%) who underwent a trial of scar the previous lower segment scar was found at Caesarean section to have dehisced or ruptured.

Cervical ripening in women with previous cesarean deliveries

OBJECTIVE

To evaluate the safety and efficacy of preinduction cervical ripening in women with previous cesarean deliveries undergoing induction of labor.

METHODS

Retrospective study of women with previous low transverse cesarean deliveries who underwent ripening of an unfavorable cervix prior to induction of labor (n = 89). Multiparas without previous cesarean deliveries undergoing ripening and induction of labor during the same time period were used for comparison (n = 61). Ripening was performed with prostaglandin E2 (PGE2) gel, or an osmotic dilator, or both. Induction of labor with oxytocin followed the American College of Obstetricians and Gynecologists' guidelines. Outcome data were analyzed using the unpaired Student's t-test or chi 2-test as appropriate. Significance was established at P < 0.05.

RESULTS

The mean gestational age was 39.6 +/- 2.6 and 38.2 +/- 2.9 weeks for the study and comparison groups, respectively. There were no differences between the groups in Bishop score, duration of the first stage of labor, maximum dose of oxytocin, indications for cesarean delivery, puerperal morbidity, birthweight, Apgar scores or NICU admissions. Sixty-four percent (57 of 89) of study women delivered vaginally compared with 82% (50 of 61) of women in the comparison group (P < 0.03). The data were analyzed separately for those women undergoing cervical ripening with PGE2 gel only. No differences were observed between the groups in any of the categories mentioned above.

CONCLUSION

Cervical ripening appears to be safe and effective in women with previous low transverse cesarean deliveries undergoing induction of labor with an unfavorable cervix.

Mifepristone for labour induction after previous caesarean section

OBJECTIVE

To evaluate the efficacy and tolerance of mifepristone in women undergoing induction of labour at term after previous caesarean section.

DESIGN

A prospective double blind placebo controlled trial.

SUBJECTS

Thirty-two women at term (after 37.5 weeks' amenorrhea) who had had a previous caesarean delivery with a low transverse uterine incision. All women had a clear clinical indication for induction of labour with unfavourable cervical conditions (Bishop's score < 4). They were randomised to receive either 200 mg of mifepristone or placebo on days one and two of a four-day observation period.

RESULTS

Thirteen women entered spontaneous labour: 11 were treated with mifepristone and two were in the control group (P < 0.01). Thirteen women, still with an unfavourable cervix on day four needed cervical ripening with vaginal tablets of prostaglandins. Of these, four had received mifepristone and nine the placebo. Mean oxytocin requirements were lower in the mifepristone group (P < 0.01) and the mean time interval between day one and start of labour was also significantly shorter in this group. Mode of delivery and neonatal outcome were similar in both groups.

CONCLUSIONS

Induction of labour is facilitated in term women with prior caesarean section by the use of mifepristone. This induction agent appears safe and useful with no adverse events on the fetus or mother.

Post caesarean section delivery

Recent clinical attention has focused upon the rising rate of caesarean sections being performed and whether patients with a previous caesarean section should be allowed a vaginal delivery. In this paper, the worldwide trend of caesarean section and the role of trial of scar following single and multiple caesarean surgery is reviewed. The role of oxytocin and regional epidural analgesia is evaluated as well as perinatal and maternal mortality. On the basis of the available data, there is no justification for the current clinical practice of almost 99% prevalence of elective repeat caesarean section in some hospitals in the North America. Oxytocin and epidural analgesia, when carefully monitored, are safe and reasonable in these patients. Watchful waiting has always been an essential virtue in obstetric management and should not be replaced by hopeful expectancy. This aspect of the art of obstetrics would appear to require rejuvenation if we are to stem the rising tide of caesarean sections.

Intrauterine pressures in labours induced by amniotomy and oxytocin or vaginal prostaglandin gel compared with spontaneous labour

Uterine activity during the first stage of labour was measured by an intrauterine transducer in 22 women induced with intravaginal PGE2 gel, in 37 induced by amniotomy and intravenous oxytocin, and in nine women in spontaneous labour. The nulliparous women in the PGE2 gel group had a significantly longer pre-established phase of labour and a significantly shorter established phase than nulliparae induced by amniotomy and oxytocin. The mean levels of total uterine activity (kPas) during labour and the uterine activity integrals (kPas/15 min) were significantly lower in nulliparae induced with PGE2 gel than in those induced by amniotomy and oxytocin. These findings suggest that PGE2 gel has a positive, beneficial effect on cervical compliance during the pre-established phase, resulting in less myometrial effort during established labour. These effects were less evident in parous women, probably because of an innate lower cervical resistance due to their previous labours. Uterine activity patterns during the 4 h leading to full cervical dilatation in nulliparae were similar in labours induced with PGE2 gel and spontaneous labours, whereas labours induced by amniotomy and oxytocin exhibited a significantly different pattern. Expulsion of the fetus during normal labour is a function of both uterine contractions and a decrease in the cervical resistance and the data suggest that induction by PGE2 gel more closely mimics spontaneous labour, whereas the predominant effect of oxytocin is to stimulate myometrial activity.

Vaginal delivery in first pregnancy following a primary caesarean section

A retrospective study was performed on 131 women who had trial of scar in their first pregnancies following a primary caesarean section. The vaginal delivery rate was 81.7% and this rate was not significantly influenced by the indication for the previous caesarean section. It is advocated that patients for trial of scar should be selected on individual merits rather than on the nature of the indication for previous caesarean section.

Trial of labour following prior section; a 5 year prospective study (1982-1987)

Between 1982 and 1987, 506 women previously delivered by Caesarean section were subjected to a trial of labour. Vaginal delivery was achieved in 78.6% with only 1 true rupture of the scar (0.2%). There were no intrapartum or neonatal deaths. Moreover, 7 of the 8 antepartum stillbirths were due to asphyxia, and, as the perinatal mortality rate for the study group was higher than for the overall population, the need for antenatal surveillance in previously sectioned patients is emphasized. Induction of labour was performed in 127 patients with 74.1% achieving vaginal delivery. Oxytocin was administered to 162 patients for either induction or augmentation of labour and 80.3% had a vaginal delivery, with 1 true rupture and 4 bloodless dehiscences. It is concluded that trial of labour following prior section is associated with little risk of true rupture, and with no added risk to the fetus. Our policy and management has helped maintain over the past 5 years an overall moderate Caesarean section rate (10-11%) with a low perinatal mortality rate.

Caesarean section and trial of scar

A retrospective study over a 16-year interval at the Mercy Maternity Hospital was made to analyse the contribution made by repeat Caesarean to the overall Caesarean section rate. The practice of trial of scar was examined with reference to the selection of patients, the conduct of labour, and the risks incurred by the mother and infant. The literature has been reviewed. The overall Caesarean section rate was 13.1% with 39.1% being repeat Caesarean sections. The primary rate has increased from 6.6% to 9.3% while the incidence of repeat Caesarean has increased from 2.7% to 6.8%. Of the 4,892 patients with one or more previous Caesarean sections, 1,577 (32.0%) were allowed a trial of scar, 1,197 (75.9%) of whom achieved a vaginal delivery. Thirteen patients sustained a ruptured uterus (0.82%) and 2 of the infants died (perinatal mortality 0.13% due to this complication alone).

Prostaglandin E2 in induction of labour: a pharmacokinetic study of dose and treatment protocols

The absorption of administered prostaglandin E2 (PGE2) into the term uterus was analysed, by measurement of intrauterine PGE2 and PGF 2 alpha, in 137 women. Amniotic fluid was sampled after elective Caesarean section, or at rupture of the membranes, and fetal membranes were collected after delivery of the placenta. Within 2 h of administration of a PGE2 pessary (500 micrograms), a significant elevation in amniotic fluid PGE2 was detected. Exogenous PGE2 stimulated the production of intrauterine PGE2 and PGF2 alpha, causing an elevated PGE2 concentration in amniotic fluid, and increased PGF2 alpha in fetal membranes. These studies indicate that the administration of as little as 500 micrograms of PGE2 pessary, resulted in elevated intrauterine PGE2. Exogenous PGE2 (2.5 mg) administration resulted in increased concentrations of PGF2 alpha in the fetal membranes. Considerable local release of PGs was observed at the site of membrane rupture, and this influenced the method of amniotic fluid sampling used in this study.

Can the number of cesarean sections be reduced without risk? An analysis of rates and indications in a university clinic

This study concerns women followed from the first trimester of pregnancy, in a university clinic in Paris in 1977, 1979 and 1981. The cesarean section rate was separately analysed for primiparas, and multiparas with and without previous cesarean section. The overall rate of cesarean section was 11.4% in 1977, 17.2% in 1979 and 21.1% in 1981. The 9.6% increase observed between 1977 and 1981 is mainly attributable to an increase in primary cesarean section, particularly among primiparas, between 1977 and 1979. This does not seem to have arisen from sample variations. There is a change in obstetrical attitude and more cesarean sections are performed in cases of hypertension, breech presentation or intrauterine growth retardation. The greater number of previously sectioned women explains the increase in the rate between 1979 and 1981. The main fact among primiparas is the 18.8% increase in diagnosis of dynamic dystocia between 1979 and 1981. Three key areas allow us to envisage a reduction in cesarean section rate: obstetrical attitude towards previous cesarean section, breech presentation, and management of labor, whose perturbations lead to diagnosis of dynamic dystocia.