Evaluation of different policies for the management of labour. Effect of early amniotomy on the risk of dystocia in nulliparous women. The Canadian Early Amniotomy Study Group. A trial of amniotomy in a Palestinian hospital. A randomised controlled trial of early versus delayed use of amniotomy and oxytocin infusion in nulliparous labour. Randomised trial comparing a policy of early with selective amniotomy in uncomplicated labour at term. A randomized controlled trial of early amniotomy. A controlled trial of a program for the active management of labor. Randomized trial of amniotomy in labour versus the intention to leave membranes intact until the second stage. Early versus late amniotomy for labor induction: a randomized trial.
Various policies of management of prolonged labour have been proposed to prevent its two main consequences--caesarean section and fetal distress. Two randomised controlled trials were organised; the first to assess the value of amniotomy with oxytocin compared to a more conservative approach. The second trial compared the effect of continuous professional support during labour with the intermittent presence of a member of staff. These were multicentre studies in several countries of Europe. Preliminary results of early amniotomy suggested no difference in the rate of operative delivery. Continuous professional support was associated with a significant reduction in operative deliveries. Early amniotomy has been advocated as a means of preventing dystocia, but its efficacy has not been studied prospectively. The purpose of this multicenter study was to determine whether routine early amniotomy reduces the risk of dystocia for nulliparous women in spontaneous labor.
                We studied 925 nulliparous women in labor, who were stratified according to the degree of cervical dilatation (< 3 cm vs. > or = 3 cm) and randomly assigned to either early rupture of the membranes (amniotomy group) or conservative management of labor (conservative-management group). Dystocia was defined as a period of at least four hours after dilatation of the cervix to 3 cm had been reached during which the mean rate of cervical dilatation was less than 0.5 cm per hour.
                Dystocia was significantly less frequent in the amniotomy group than in the conservative-management group (34 percent vs. 45 percent; relative risk, 0.8; 95 percent confidence interval, 0.6 to 0.9). The median length of time from randomization to full dilatation was 136 minutes shorter in the amniotomy group, and there was a trend toward less frequent use of oxytocin among the women assigned to amniotomy (36 percent vs. 41 percent; relative risk, 0.9; 95 percent confidence interval, 0.8 to 1.0). In a stratified analysis, the frequency of dystocia associated with amniotomy was reduced only among women with > or = 3 cm initial dilatation. The cesarean-section rate was similar in the two groups (amniotomy, 12 percent; conservative management, 11 percent). There were no statistically significant differences in outcome between the infants delivered by the women in the two groups; the measures of an adverse outcome included admission to a neonatal intensive care unit, five-minute Apgar score below 7, and arterial cord-blood pH below 7.2.
                Early amniotomy is an effective method of shortening the duration of labor and reducing the frequency of dystocia among nulliparous women in labor, but it does not lower the rate of cesarean section. This randomised controlled trial of routine amniotomy was carried out in a developing country setting to investigate the effect of this common procedure on the duration of labour, intra-partum interventions and selected newborn and maternal outcomes. In a Jerusalem teaching hospital, 533 multiparous and 157 nulliparous low-risk women were randomised to either amniotomy or intent to conserve membranes. For multiparae, the median duration from randomisation to full dilatation was 95 and 160 min, respectively in the intervention and control arms (p < 0.001); for nulliparae it was 210 and 270 min, respectively (p < 0.001). In both groups, oxytocin was used less in the intervention arms (p < 0.001), and no difference in mode of delivery and immediate outcomes was detected. However, given the risks of this intervention and these study findings indicating an overall short duration of childbirth, amniotomy should be limited to cases of abnormal progress of labour. To compare routine amniotomy and early intravenous oxytocin (active management of labour) with a more selective use of amniotomy and oxytocin in women in true labour who received comparable continuous supportive midwifery care.
                Randomised controlled trial of nulliparous clinic patients in spontaneous labour at term.
                Labour and delivery ward of a university teaching hospital.
                Three hundred and six parturients: 152 received active management of labour; 154 were more selectively managed.
                1. Active management: early amniotomy, early use of oxytocin. 2. Selective intervention management: no routine amniotomy and more selective use of oxytocin.
                Use of oxytocin and amniotomy. Labour duration, mode of delivery.
                Maternal characteristics were comparable in both groups. Amniotomy was more often performed (91% versus 57%, P <0.01) and oxytocin more often used (53% versus 27%, P < 0.01) in the active management group. The first stage of labour, however, was only shortened by half an hour in the active management group (254 min versus 283 min, P = 0.087). Caesarean section rate (3.9% versus 2.6%), spontaneous vaginal delivery rate (78% versus 79%) and neonatal outcome were not significantly different between groups.
                Within a set-up of strict labour diagnosis and supportive midwifery care, routine amniotomy and early use of oxytocin offered no advantage over a more selective use of amniotomy and oxytocin in terms of mode of delivery and labour duration. To compare two management policies: rupture of the fetal membranes when women are in normal labour or leave them intact as long as feasible.
                The labour ward of a city university hospital.
                Automated randomised clinical trial.
                1540 women in uncomplicated term labour. Data on labour duration, blood loss, oxytocin use and fetal condition were collected from 1132 women. Some data from nulliparous women has been presented earlier by the UK Amniotomy Group.
                Duration of labour, Apgar score, fetal morbidity and maternal morbidity including perineal injury, mode of delivery, epidural rates and the total number of vaginal examinations in the first stage of labour after amniotomy.
                Amniotomy at the next vaginal examination or amniotomy only if indicated. The median cervical dilatation at membrane rupture was 2 cm greater in the first group.
                A policy of routine amniotomy in labour had no measurable advantage over selective amniotomy for parous women (difference = 4 min) but shortened labour in nulliparous women by 1 h (Mann-Whitney U test: P < 0.05). There was a suggestion of a higher caesarean section rate (OR 1.9; 95% CI 0.9-3.5), and there were more vaginal examinations after membrane rupture in the group allocated routine amniotomy. There were no measurable differences in oxytocin use, fetal condition at birth, retained placenta rates, blood loss, pain or analgesia requirements.
                Routine amniotomy may shorten the first labour but not subsequent ones. There is a suggestion that routine surgical interference may be harmful by increasing the risk of caesarean section, and this agrees with data from other trials (common odds ratio 1.2; 95% CI 0.92-1.6). OBJECTIVE-To determine if a policy of early amniotomy resulted in a reduction in mean labour duration when compared to a policy of conservation of the membranes. DESIGN-A single-centre randomized controlled trial. SETTING-A tertiary care teaching hospital in Alberta, Canada. SUBJECTS-Ninety-seven term nulliparae in spontaneous labour, baby in cephalic presentation. INTERVENTION-Early amniotomy versus intent to keep membranes intact. MAIN OUTCOME MEASURES-Interval from randomization to delivery, rate of abnormalities of fetal heart rate tracings, cord artery blood pH, Apgar scores. RESULTS-The mean interval from randomization to delivery was 390.9 (SE 29.1) min in the amniotomy group and 442.9 (SE 34.1) min in the control group (P = 0.251). There were no differences between groups in the occurrence of fetal heart rate tracing abnormalities, nor was there a difference in the proportion of babies with abnormal Apgar scores, or abnormal cord pH (less than 7.20). CONCLUSION-The results of the study fail to support the long held belief that early amniotomy is an effective method for reducing labour duration. Over the past two decades, the rate of cesarean section in the United States has risen from 5 percent to 25 percent of deliveries, primarily because of the increased frequency of dystocia (arrest of labor). One strategy that has been proposed for increasing the rate of vaginal delivery is a program of active management of labor that encourages early amniotomy, early diagnosis of slow progress in labor, and the use of higher than usual doses of oxytocin; the efficacy and safety of this approach are uncertain, however.
                We conducted a randomized trial in which nulliparous women in spontaneous labor at term were randomly assigned to either active management of labor or traditional management. With active management, amniotomy was performed within one hour of the diagnosis of labor, and when the rate of cervical dilation was less than 1 cm per hour, oxytocin was infused at an initial rate of 6 mU per minute. The dose was increased by 6 mU per minute every 15 minutes (to a maximum of 36 mU per minute) until there were seven contractions every 15 minutes.
                For the women assigned to active management (n = 351), the cesarean-section rate was 10.5 percent, as compared with 14.1 percent for those assigned to traditional management (n = 354, P = 0.18). The 26 percent reduction in the cesarean-section rate was due primarily to a decrease in dystocia. After we controlled for potential confounding variables, the reduction in the rate of delivery by cesarean section was statistically significant (odds ratio for women given active as compared with traditional management, 0.57; 95 percent confidence interval, 0.36 to 0.95). With active management, the average length of labor was shortened by 1.66 hours, principally because of earlier amniotomy and earlier use of oxytocin. There was no increase in maternal or neonatal morbidity, and there were significantly fewer infectious complications in the mothers.
                The program we studied for the active management of labor reduces the incidence of dystocia and increases the rate of vaginal delivery without increasing maternal or neonatal morbidity. To compare by randomized prospective clinical trial the outcome of labours which are managed with the intention to leave the membranes intact, compared with the practice of elective artificial rupture of the membranes (ARM) in early established labour.
                Prospective randomized controlled trial of low risk women admitted in spontaneous labour, with intact membranes.
                The labour ward of St. James's University Hospital, Leeds, UK.
                362 women in spontaneous labour with intact membranes and no evidence of fetal distress, between 37 and 42 weeks gestation. During the course of the trial it was found that some randomization cards could not be accounted for and a system of daily checks was instituted. The results were analysed for all recorded women (n = 362) and after institution of the more rigorous system (n = 120).
                The duration of each phase of labour, epidural rate, prevalence of an abnormal cardiotocograph (CTG) (assessed blind), method of delivery and neonatal outcome.
                178 of the 183 women (97%) in the ARM group had their membranes ruptured in early labour, and 83 (46%) of the 179 women allocated to non-intervention had ARM performed at some stage. A significant decrease in the duration of labour (mean 8.3, SD 4.1 h vs mean 9.7, SD 4.8 h, n = 156; P = 0.05) was found amongst primigravidae allocated to ARM when compared with non intervention. The duration of the second stage of labour was unaffected. In the ARM group the epidural rate was higher and labour was more often complicated by CTG abnormalities. There were no differences in the method of delivery, fetal condition at birth (cord blood lactate, Apgar score) or postpartum pyrexia between the ARM and non-intervention groups. The same trends were observed when analysis was confined to women entered into the trial after the system of rigour was instituted.
                Routine ARM results in labour that is slightly shorter than if the membranes are allowed to rupture spontaneously but more epidurals are used suggesting that labour is more painful. There are fewer fetal heart rate abnormalities if the membranes are left intact but amniotomy has no effect on fetal condition at birth. Our purpose was to determine the impact of early and late amniotomy on labor induction with continuous oxytocin infusion at term.
                A total of 209 women admitted for labor induction were randomized to early or late amniotomy. The early amniotomy group (n = 106) had membranes ruptured as soon as it was deemed safe and feasible. The late amniotomy group (n = 103) had membrane rupture performed at > or = 5 cm dilatation. The first 103 women received a continuous oxytocin infusion with incremental adjustments at 60-minute intervals as required. The next 106 women had adjustments every 30 minutes as required. Statistical analysis was confined to concurrent groups.
                Early amniotomy was associated with shorter labor (13.3 vs 17.8 hours, p = 0.001), chorioamnionitis (22.6% vs 6.8%, p = 0.002), and significant fetal umbilical cord compression (12.3% vs 2.9%, p = 0.017). The benefit regarding shortening of labor was limited to women having oxytocin increments every 30 minutes as required (13.3 vs 17.8 hours, p = 0.001). Alternatively, the increase in chorioamnionitis was confined to the 60-minute group (39% vs 11%, p < 0.001), which also demonstrated a trend toward increased moderate and severe variable decelerations (19.6% vs 6.4%, p = 0.08).
                When a protocol of 60-minute increments in oxytocin infusion rate is desired, amniotomy should be performed late in labor to reduce chorioamnionitis and significant umbilical cord compression. Alternatively, if early amniotomy is necessary, oxytocin should be adjusted every 30 minutes as tolerated.
On the basis of the findings of this review, we cannot recommend that amniotomy should be introduced routinely as part of standard labour management and care. We recommend that the evidence presented in this review should be made available to women offered an amniotomy and may be useful as a foundation for discussion and any resulting decisions made between women and their caregivers.