A randomized prospective trial comparing single dose prostaglandin E2 vaginal gel with forewater amniotomy for induction of labour. Role of the cervix in the induction of labor.
A prospective randomized parallel-group study was carried out to compare the efficacy of a single dose vaginal prostaglandin E2 gel with forewater amniotomy for induction of labour at term in 260 parturients (110 primigravid and 150 parous women) with low risk pregnancy and favourable cervix. In the prostaglandin E2 (PGE2) managed group, the primigravidae were treated with 2 mg PGE2 gel and parous patients with 1 mg PGE2 gel. Forewater amniotomy was performed 4 h later, or sooner if women requested analgesia. In the amniotomy group, artificial forewater amniotomy was carried out and a repeat cervical assessment done 4 h later, or sooner if women requested analgesia. In both groups, intravenous oxytocin was established if there was evidence of disordered uterine activity, 6 h after the start of initial intervention. An assessment of consumers' views was carried out by using a standardized questionnaire completed 48 h after delivery. There was a significant reduction in the requirement for oxytocin augmentation in women treated with PGE2: primigravidae, odds ratio (OR), 0.27 and 95% confidence interval (CI), 0.12-0.61; multiparae, OR, 0.19 and 95% CI, 0.08-0.45. Fewer primigravidae managed with PGE2 gel required epidural analgesia (OR, 0.16; 95% CI, 0.06-1.00). Fewer parous women managed with PGE2 gel required parenteral opiates (OR, 0.44; 95% CI, 0.23-0.85) and more women required inhalation analgesia or no analgesia (OR, 2.22; 95% CI, 1.76-2.79). The intervention to delivery intervals were shortened in PGE2 groups independent of parity but the differences were not significant.(ABSTRACT TRUNCATED AT 250 WORDS) A study on induction of labor was carried out to test the hypothesis that changing the cervix will enhance the effectiveness of induction of labor. Fifty pregnant women near term with Bishop scores of 4 or less were divided into 5 study groups, in which a 12-hour preparation phase procedure was carried out to produce cervical or myometrial changes. All women had continuous measurement of uterine activity by an extraovular catheter. The patients were divided into 1) control subjects, and into groups treated with 2) laminaria, 3) Foley catheter, 4) amniotomy, and 5) oxytocin infusion. These preparation techniques were used for 12 hours, after which rupture of membranes was carried out in all cases. Although all procedures significantly changed the cervix, none but oxytocin affected the induction-to-delivery interval. The authors concluded that when a study design rigidly controls for cervical Bishop score, timing of rupture of membranes, and oxytocin infusion rates, the cervical preparation alone will not enhance inducibility.
Data are lacking about the value of amniotomy alone for induction of labour. While there are now other modern methods available for induction of labour (pharmacological agents), there remain clinical scenarios where amniotomy alone may be desirable and appropriate, and this method is worthy of further research. This research should include evaluation of the appropriate time interval from amniotomy to secondary intervention, women and caregivers' satisfaction and economic analysis.
[Note: the two citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]