Membrane sweep: what does it really involve?

Au cours de cet examen pelvien, le praticien peut "balayer les membranes", c'est-à-dire utiliser ses doigts pour séparer la poche d'eau amniotique de la paroi utérine. Cela peut alors déclencher la libération de médiateurs chimiques, les prostaglandines, qui assouplissent le col de l’utérus et préparent au travail et également irriter le col de l’utérus provoquant ainsi sa contraction[1]. 
 

La concentration plasmatique de prostaglandines, à la suite du décollement des membranes, a été retrouvée à un taux équivalent à 10 % de celui constaté au cours du travail [2].

Il n'est pas garanti que le décollement des membranes va permettre le déclenchement de l'accouchement ou les contractions. Le décollement des membranes est souvent proposé comme première option pour faire démarrer le travail et favoriser un accouchement naturel avant de fixer une date de déclenchement.

Studies are not necessarily reliable

In a review of 44 studies, they examined the effect of membrane sweeping on the induction of labour [3]. 14 studies indicated that if the cervix was closed, they performed a cervical massage instead of a membrane sweep. Thus, in these 14 studies, "membrane sweeping" could in fact have been either a cervical massage or a sweep. 

For the most part, the authors judged that the studies they included had a low or unclear risk of bias.

However, in general, the risk of performance bias was high, as the 44 studies did not carry out a study blinding, otherwise known as blinding. 

Blinding means that clinicians and researchers do not know who is receiving which treatment — whether the actual treatment, no treatment, or a placebo. When blinding is not used, as is the case in all these studies, it can introduce bias, meaning clinicians may be inclined to provide better care to the treatment group in the hope that it proves effective. 

For example, if a provider knew that a person was in the treatment group for membrane sweeping, they might delay scheduling a formal induction in the hope that the person in the treatment group would go into labour spontaneously on their own.

The results are mixed

Cervical massage: a better alternative?

There is less data available on whether membrane sweeping or cervical massage can contribute to cervical ripening or softening. In a randomised trial, 165 participants with a low Bishop score — that is, an unripe cervix at 41 weeks and four days of pregnancy — were randomly assigned to membrane sweeping, cervical massage only, or no treatment [6].
 

Both the cervical massage and membrane sweeping groups were associated with a significant increase in mean Bishop score 48 hours after treatment compared with the control group. This is evidence that cervical massage may be an effective alternative to membrane sweeping and that it could be offered to pregnant women whose cervix is closed. 

When the reviewers of the study looked at other outcomes, they found no difference between the groups regarding the rate of caesarean sections, the use of forceps or ventouse to assist delivery, or serious illness or death in mothers or babies. 

Risk of premature rupture of membranes
 

It is possible that membrane sweeping, but not cervical massage, increases the risk of membrane rupture before labour. The case where the waters break BEFORE the onset of labour is referred to as "premature rupture of membranes", regardless of the stage of pregnancy (in other words, the term "premature" refers solely to the timing relative to the onset of labour).

Labour often begins within the hours following membrane rupture. It should be noted that the risk of foeto-maternal infection increases significantly after 12 hours of ruptured membranes.

In a randomised trial of 300 women, the risk of membrane rupture was 9% in the group who underwent a membrane sweep, compared to 0% in the group who received no treatment, for women whose cervix was dilated by more than 1 cm at the time of the membrane sweep [7]. 

Another similar randomised study of nearly 300 women showed that membrane sweeping significantly increased the risk of premature rupture of membranes (38% rupture rate following membrane sweep compared to 26% with no intervention) [8].

Mais les conséquences de ce risque sont à nuancer et à mettre en regard avec le fait que :

- Cette situation est majoritairement retrouvée chez les femmes ayant un col dilaté à plus de 1 doigt (donc pour des femmes à qui on proposerait de toute façon plutôt la rupture de la poche comme méthode de déclenchement).

- Si le décollement provoque une rupture, le protocole est de se laisser 48h d’expectative avant de déclencher, ce qui revient un peu à la même chose que le déclenchement prévu initialement. En revanche, il est vrai que toute rupture prolongée implique un risque d’infection foeto-maternel.

Pain and bleeding

Pain during vaginal examination and other side effects are more frequently reported by women who have had a membrane sweep [9]. 

A randomised study of more than 700 women [10], who either had a membrane sweep or no intervention, showed that the sweep multiplied vaginal bleeding by 6. The reason: the cervix is highly vascularised. The more it is touched, the more it bleeds.

They also studied the pain associated with this practice, and showed that 31% of women said it was not painful, 51% said it was somewhat painful, and 17% said it was painful or very painful. 

Parfois, cette intervention est pratiquée de manière routinière lors d'un examen vaginal sans qu'il y ait eu de discussion sur le consentement éclairé. Cette pratique doit être réalisée si et seulement si vous l’acceptez, et ne doit pas être une pratique faite sans vous prévenir.

Son efficacité pour déclencher le travail est controversée, certaines études montrent un léger effet tandis que d’autres ne montrent pas d’effet. Le risque est qu’il ne provoque des contractions douloureuses et régulières, sans que cela provoque de modifications cervicales (faux travail). De nombreuses sages-femmes préfèrent le pratiquer sur les femmes ayant déjà eu des enfants

Des personnes ont signalé avoir ressenti des douleurs ou un inconfort lors de l'intervention. Vous pouvez également avoir des saignements après l'intervention. 

Le décollement des membranes, mais pas le massage cervical, peut augmenter le risque de rupture prématurée des membranes avant le travail.

La tisane feuille de framboisier serait une alternative naturelle plus sûre.