To sweep…or not to sweep?
When women go over their ‘guess’ date, and with some practitioners, as they approach it, they may be offered a membrane sweep, in the hope that it will get their labour started.
What is it?
A “sweep” is a non-chemical method of induction. It involves the practitioner attempting to separate the water bag (amniotic sac) from the uterus. One or two fingers are inserted into the cervix and the practitioner tries to get their fingers between the water bag and the uterus, following the cervix around and gently separating the membranes.
Afterwards, you may experience some ‘show’ (blood stained mucous) or spotting and mild cramps, regardless of whether or not labour starts.
How does it work?
It may encourage the body to produce prostaglandins, causing the cervix to soften and thin, which may get labour going within 48 hours.
What are the chances that it will work?
According to a Cochrane review in 2005, having a sweep at 40 weeks does reduce the length of pregnancy and the incidence of going beyond 41 weeks. However, in order to avoid one induction of labour, a sweep would need to be performed in 8 women.
What are the benefits?
The woman may experience a physiological onset of labour rather than a chemical induction. A sweep increases the chances of going into labour within 48 hours and of giving birth within one week. (Keirse, 1995; McColgin et al, 1990; Weissberg and Spellacy, 1977)
What are the risks?
There is a risk that the water bag may be broken accidentally, which means that the woman will then be told she will have 24 hours to begin labour before she is chemically induced. Although some of the evidence indicates that prelabour rupture of the membranes is not a risk of sweeps (Boulvain et al, 2005; Wong et al, 2002), Hill et al found that there was increased risk of rupture of the membranes if the cervix was more than 1cm dilated (9% of women experienced PROM). Anecdotally, a few mothers on the GentleBirth mums group had their waters release accidentally during the procedure recently.
Some of the research indicates that infection is not an issue (NICE 2008). However, women who are Group B Strep positive should think carefully before having a sweep as GBS can cross intact membranes. As GBS testing is not routine in Ireland, few women know their GBS status and up to 25% of women are carriers of Group B Strep.
Some women may find sweeps unpleasant and uncomfortable. They may also lead to “false starts” where women have show and crampiness and think labour is on the way, but it then dies down. Some women find this to be upsetting.
Are sweeps recommended by NICE (UK National Institute for Clinical Excellence) guidelines?
Membrane sweeps are not recommended for routine use beyond 38 weeks in order to avoid an induction of labour. The guidelines recommend that a sweep should be offered to women who have not had a baby before at their 40 and 41 weeks antenatal visits, and to women who have had a baby before at their 41 week appointment (NICE 2008).
Why would I want a sweep?
You may want to have a sweep if:
- There is a medical indication for induction and you want to see if a sweep will start labour, before proceeding to other induction methods.
- You are 42 weeks pregnant.
- You are almost 42 weeks pregnant and you are planning to have your baby at an MLU or at home under the HSE or a hospital scheme (you cannot have your baby in the MLU beyond 42 weeks and you need consultant sign off, which can be difficult to obtain, to have a HSE home birth beyond 42 weeks).
You may not want to have a sweep if:
- There is no medical reason to induce labour.
- You want to let labour start in its own time without any interference.
- You have had unexplained vaginal bleeding during your pregnancy.
- Induction is urgently required and it would be safer to start induction with medication.
- You have Group B Strep (GBS) in your vagina.
Unfortunately, as some of the women below have experienced, non consensual sweeps sometimes happen in Irish maternity units. If you do not want a sweep, declining a vaginal examination may be your best course of action.
“I had two sweeps, at 40 weeks + 11 days and 40 weeks + 13 days. Neither of them did much. I had some show after the second one, but that was it. I wanted to go into labour before 42 weeks because I wanted to have a home birth. I ended up being induced due to my waters going and no labour starting after 40 hours. I think the sweeps probably contributed to the waters leaking. I wouldn’t make the same decision again – I’d just book with a different maternity unit that might be more likely to sign me off for extra days”.
“I had a sweep at 40 + 4, had a bit of show that evening & period cramps for the next 5 evenings before she arrived. The doctor told me I was very ready to go at the time & she thought I’d be back in that evening which I was delighted about coz I was carrying very low & was quite uncomfortable for the last 3/4 wks. I really wanted to get things going & avoid induction. I was glad we avoided induction but I don’t think I would get it done again so early – I think I’d hold off til nearer term + 14. It was not pleasant at all & maybe she would have arrived when she did regardless”.
“I had two sweeps desperately trying to get labour going for homebirth on my first, but now I know full sure the hospital dates where at least a week out so they were never gonna work. On my second, I had a sweep at term plus 5 (my acupuncturist had already told me I was on the brink a couple of days beforehand) and went into labour a few hours later. I would do the same again as my thinking was if I declined it and went the full 14 days or more over and ended up with induction and another section then I would never have forgiven myself for not exploring every avenue of getting things started”.
“I had one but didn’t know until afterwards. The consultant said she just wanted to check how things were as they were considering keeping me in I was just due & had protein in my urine so they were concerned and wanted to see how likely I was to go. When she was done, after I asked what the story was she said ” oh yeah and I did a sweep too so hopefully that will get things going. At the time, I was just a bit surprised cos I thought they had to ask first but at the same time I was a bit relieved or excited or some mixed up emotions cos I was being kept in unexpectedly & baby might come soon. I hadn’t a clue back then, & in all the stuff I had looked up I hadn’t read anything negative about it. It’s only now I know better”.
Boulvain M, Stan C, Irion O. (2005) Membrane sweeping for induction of labour. Cochrane Database of Systematic Reviews 1: CD000451.
Hill MJ, McWilliams GD, Garcia-Sur D, Chen B, Munroe M, Hoeldtke NJ. The effect of membrane sweeping on prelabor rupture of membranes: a randomized controlled trial. Obstet Gynecol. 2008 Jun;111(6):1313-9. See: http://www.ncbi.nlm.nih.gov/pubmed/18515514
Keirse MJNC. (1995) Stripping/sweeping membranes at term for induction of labour: In: Keirse MJNC, Renfrew MJ, Neilson JP, Crowther C. (Eds.). Pregnancy and childbirth module. The Cochrane Pregnancy and Childbirth Database. The Cochrane Collaboration 2.
McColgin SW, Hampton HL, McCaul JF, Howard PR, Andrew M, Morrison JC. (1990) Stripping membranes at term: can it safely reduce the incidence of post-term pregnancies? Obstetrics and Gynaecology. 76: 678-80. Weissberg SM, Spellacy WN. (1977) Membrane stripping to induce labour. Journal of Reproductive Medicine 19(3): 125-7.
National Institute for Health and Clinical Excellence. (2008) Induction of labour. London. See: http://publications.nice.org.uk/induction-of-labour-cg70/guidance#recommended-methods-for-induction-of-labour
Wong SF, Hui SK, Choi H, Ho LC. (2002) Does sweeping of membranes beyond 40 weeks reduce the need for formal induction of labour? BJOG 109: 632-6.