What is a membrane sweep?

The membrane sweep (also known as a sweep, sweeping of the membranes, stretch and sweep, or membrane stripping) is a process that involves a doctor or midwife, gently inserting 2 fingers into your vagina and then your cervix (neck of the womb) and moving the fingers around in a circular motion to separate the outer membranes from the inner surface of your womb. The membranes or the amniotic sac is the bag of fluid surrounding your baby where he/she grows and develops for nine months.

The aim of a sweep is to stimulate the release of prostaglandins which may kick start the labour process, without a formal induction. It is usually performed when the mother is over 40 weeks pregnant, or an induction of labour is imminent.

How is it performed?

Doctors or Midwives may perform a membrane sweep in a clinic, or at a hospital. The process typically takes less than 10 minutes. The practitioner will wear sterile gloves and use a lubrication gel. He or she will then perform a cervical examination to determine if your cervix is open. If the cervix is open, they will insert a finger into your cervix and perform a sweeping motion. This will separate your membranes from your cervix. If the cervix isn’t open, a sweep can’t be performed.

Why is a membrane sweep used?

A membrane sweep is intended to stimulate the release of hormones known as prostaglandins. Prostaglandins are hormones that are associated with labour because they cause smooth muscle contractions, which help to “ripen” the cervix, or cause the cervix to soften so that a baby can more easily pass through the birth canal. Think of how a banana gets softer and riper, the cervix also becomes softer (or ripe) and then dilates.

The intent is to stimulate labour within around 48 hours. If a sweep is unsuccessful, an induction may be indicated, depending on your gestation and the health of you and your baby.

Who shouldn’t have a sweep?

We will not usually perform a stretch and sweep if:

• Baby’s head is not pointing downward
• You are not 40 weeks pregnant or more
• You have a vaginal infection
• Your membranes have already ruptured (your water has broken)
• Your placenta is low-lying

Does a sweep work?

According to a review of study data published in The Cochrane Review, a sweep performed at term was associated with a higher incidence of spontaneous labour and reduced induction.

Risks and side effects of a sweep

A sweep can cause side effects, including:

• Bloody show or mild bleeding (may appear brown with time)
• Cramping that can feel like menstrual cramping
• Discomfort during the procedure
• Irregular contractions (which may not necessarily lead to labour)

There’s also a risk that a stretch and sweep could break the amniotic sac. This is sometimes known as your water breaking.

There isn’t any data to indicate that a sweep increases the risk of infection to mother and baby when it’s properly performed.

If you experience side effects like bleeding bright red blood, your water breaking, or intense pain that doesn’t decrease with time, call your doctor or hospital. You shouldn’t attempt to perform a sweep on yourself. Only a licensed professional should do it.

The takeaway

A sweep is a process thought to increase a woman’s likelihood of going into labour spontaneously, without the interventions of medications and/or surgery. Women who wish to go into labour naturally may prefer this option when compared to medical induction. If the sweep isn’t effective the first time, it may repeat it at a later time, usually a few days later. If your body doesn’t respond to a sweep or medical induction or a caesarean delivery may be necessary.