The practice of “stretching and sweeping” women’s membranes is probably older than most of the interventions currently offered to pregnant women, and its use is controversial in a number of ways. Firstly, it is one of those practices on which midwives have wildly differing opinions; some are convinced that it is a marvellously effective way of preventing the need for medical induction of labour for post-dates, while others feel it is ineffective at best, and, at worst, an invasion of a woman’s bodies at what is generally considered to be an intensely vulnerable time.
Alongside these diverging midwifery views, the findings of research into this area have been appraised and debated for the last decade or so, with further variations in the conclusions that different people have drawn. As the earliest evidence-based summaries were developed, both Kierse (1994) and Enkin et al (1995) concluded that there was not enough evidence to assess the effectiveness of the stretch and sweep, which led to frustration on the part of some clinicians (e.g. Griffiths 1995), because they felt that other research in this area had been ignored, and a potentially valuable intervention was thus being overlooked.
Since then, more studies have been conducted and incorporated into metaanalyses and reviews of the evidence, and the 2005 Cochrane review (Boulvain et al 2005) reported that, if you sweep every woman’s membranes at term, this will lead to an overall reduction in the length of pregnancy and to less women still being pregnant past 41 weeks. However, calculation of the number needed to treat (NNT) suggests that eight women need to undergo stretching and sweeping in order to prevent one woman’s pregnancy becoming “post-dates”. The authors of this Cochrane review are among those who caution that the potential benefits need to be balanced against women’s discomfort, and point out that routine sweeping of the membranes at 38 weeks is not associated with clinically important benefits.
Yet, soon after the publication of this update, a number of Trusts had moved towards a policy of routinely ‘offering’ a stretch and sweep. In some areas, there is no differentiation between the approaches taken with primigravid and multiparous women, little acknowledgement of the potential side effects of membrane sweeping – which include discomfort, bleeding and irregular contractions and an apparent unawareness that early membrane sweeping is not effective, as shared with me by one midwife who said “…they’re now recommending it every week from 38 weeks onwards … it’s a case of give them an inch and they take a mile…”
The web of issues in this area seems very tangled. We have to unpack the differences between offering a stretch and sweep on an individual, woman by woman basis, and recommending the same intervention routinely. We need to be clear about whether we are offering a stretch and sweep as an alternative or precursor to medical induction, or whether we are offering it in the hope of not reaching that point in the first place. Where women would not consent to induction, there may be less call to discuss the stretch and sweep – so perhaps we should avoid offering or recommending a membrane sweep before the wider issue of induction is properly discussed. These wider issues, in turn, include questions around whether routine induction of labour somewhere between 41 and 42 weeks actually reduces perinatal mortality and morbidity, whether routine dating of pregnancy is useful or effective, and how we can find time to talk women through all of these issues so that they can make the choices that are right for them. It would seem that, the more we attempt to find out with our relatively new tools of research and review, the more complex the issues become for both women and their midwives. Ultimately I can’t help but feel that, with this and many other issues, we have to find new ways of replacing sweeping policies with broader and stretchier ways of helping women make decisions.
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A version of this article was originally published as Wickham S (2006). Unpacking Sweeping Policies. TPM 9(1):30.
Boulvain M, Stan C, Irion O. Membrane sweeping for induction of labour. The Cochrane Database of Systematic Reviews 2005, Issue 1.
Enkin M, Keirse MJNC, Renfrew M, Neilson J. Methods of inducing labour. In: A guide to effective care in pregnancy and childbirth. 2nd ed. Oxford: Oxford University Press, 1995.
Griffiths, M (1995) Must be applied critically (Letter) BMJ 1995;311:257
Keirse MJNC. Stripping/sweeping membranes at term for induction of labour. In: Enkin MW, Keirse MJNC, Renfrew MJ, Neilson JP, eds. Pregnancy and childbirth module. Cochrane database of systematic reviews. Oxford: Update Software, 1994.
An interesting series of posts relating to this issue from the UK Midwifery Archives can be found at http://www.radmid.demon.co.uk/sweep.htm