This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.
Sweeping of the membranes, also commonly named stripping of the membranes, is a relatively simple technique usually performed without admission to hospital. During vaginal examination, the clinician's finger is introduced into the cervical os. Then, the inferior pole of the membranes is detached from the lower uterine segment by a circular movement of the examining finger. This intervention has the potential to initiate labour by increasing local production of prostaglandins and, thus, reduce pregnancy duration or pre-empt formal induction of labour with either oxytocin, prostaglandins or amniotomy.
To determine the effects of membrane sweeping for third trimester induction of labour.
The Cochrane Pregnancy and Childbirth Group trials register, the Cochrane Controlled Trials Register and bibliographies of relevant papers (last searched November 2000).
The criteria for inclusion included the following: (1) clinical trials comparing membrane sweeping used for third trimester labour induction with no vaginal examination or vaginal examination for cervical assessment only or with other methods listed above it on a predefined list of labour induction methods (i.e. administration of prostaglandins and oxytocin); (2) random allocation to the treatment or control group; (3) adequate or unclear allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.
Data collection and analysis
The data extraction was done centrally and incorporated into a series of reviews arranged by methods of induction of labour, following a standardised methodology. Two of the reviewers also assessed trial quality and extracted data. To avoid duplication of data in the reviews, the labour induction methods have been listed in a specific order, from one to 25. Each review includes comparisons between one of the methods with only those methods above it on the list. Therefore, sweeping of membranes was compared to no treatment, intravaginal prostaglandins and oxytocin. Results are reported as relative risk (RR) and their 95% confidence interval (CI) and number-needed-to-treat (NNT).
Nineteen trials were included, 17 comparing sweeping of membranes with no treatment, three comparing sweeping with prostaglandins and one comparing sweeping with oxytocin (two studies reported more than one comparison). Risk of caesarean section was similar between groups (RR 0.97, 95% CI 0.73 to 1.28). Sweeping of the membranes, performed as a general policy in women at term, was associated with reduced duration of pregnancy and reduced frequency of pregnancy continuing beyond 41 weeks (RR 0.62, 95% CI 0.49 to 0.79) and 42 weeks (RR 0.28, 95% CI 0.15 to 0.50). To avoid one formal induction of labour, sweeping of membranes must be performed in seven women (NNT = 7). There was no evidence of a difference in the risk of maternal or neonatal infection. Discomfort during vaginal examination and other adverse effects (bleeding, irregular contractions) were more frequently reported by women allocated to sweeping. Studies comparing sweeping with prostaglandin administration are of limited sample size and do not provide evidence of benefit.
Routine use of sweeping of membranes from 38 weeks of pregnancy onwards does not seem to produce clinically important benefits. When used as a means for induction of labour, the reduction in the use of more formal methods of induction needs to be balanced against women's discomfort and other adverse effects.