What Is a Membrane Sweep?

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Membrane sweeping, also known as membrane stripping, is a procedure that can help induce labor in pregnant people who are close to or past their due date. A doctor or midwife will use a gloved hand to sweep the inside of the cervix in a circular motion to manually separate the amniotic sac (or membranes) from the uterus.

A membrane sweep is not intended to rupture the sac (break the waters) but is intended to stimulate the release of hormones known as prostaglandins. Prostaglandins are hormones associated with labor that cause smooth muscle contractions. This includes contractions of the uterus that can lead to labor.

Membrane sweeping is effective and safe for most people.

Pregnant woman getting a pelvic exam at gynecologist

EmirMemedovski / Getty Images

Purpose of Membrane Sweeping

The sweeping of membranes is a technique often used by doctors and midwives when a pregnancy is prolonged beyond 40 weeks, to help induce labor. A pregnancy that extends to 42 weeks of gestation or beyond (known as a post-term pregnancy) can sometimes cause fetal and maternal complications.

Risk of Prolonged Pregnancy to Babies

There are growing risks for the baby when a pregnancy approaches 42 weeks. These include:

  • Macrosomia: A condition in which a fetus is estimated to weigh more than nine to 10 pounds
  • Postmaturity syndrome: When a post-term fetus may be born with a long and lean body, lots of hair, long fingernails, and thin, wrinkled skin
  • Meconium: A greenish substance that builds up in the bowels of a growing fetus. If meconium is passed, it may get into the lungs of the fetus through the amniotic fluid. This can cause serious breathing problems.
  • Decreased amniotic fluid: This can cause the umbilical cord to pinch and restrict the flow of oxygen to the fetus.

Conditions like these can place the baby at an increased risk of illness, disability, and even stillbirth.

How Long Before My Physician Induces Labor?

Typically, tests are started at 41 weeks (if you are considered high risk, these tests will start earlier in pregnancy) to evaluate the fetus’ movement and heart rate and the amount of amniotic fluid. Doctors may use ultrasonography and electronic fetal heart monitoring to check the fetus' status. If your doctor is concerned for your baby's safety, they may bring you into the hospital to induce labor.

Risks of Prolonged Pregnancy to Pregnant People

Around 6% of pregnancies will go beyond 42 weeks.

The risks of a post-term pregnancy are often associated with delivering a large baby and can include:

  • Cesarean section
  • Forceps delivery
  • Damage to the perineum (the area between the anus and genitals)
  • Postpartum hemorrhage

Benefits of Membrane Sweeping

Membrane sweeping has been found to be effective at inducing labor for the majority of pregnant people. Effects are not spontaneous, though, and the procedure may take several days to work. Studies show that, on average, people who had their membranes swept went into labor several days earlier than those in the control group.

This procedure is often used before or instead of other induction techniques, particularly for those who may prefer to avoid more invasive intervention methods or using medications like Pitocin (a synthetic form of the hormone oxytocin).

Is the Procedure Effective?

In most cases, membrane sweeping increases the likelihood of spontaneous labor. Healthcare providers usually only need to carry out the procedure once to induce labor successfully. However, some people may require multiple sweeping procedures.

A 2014 study published in the Journal of Clinical Gynecology and Obstetrics looking at the efficacy and safety of membrane sweeping found that it reduced total gestation time.

The study, which included 80 pregnant people who had the procedure and 80 who did not, showed that:

  • Of those who received membrane sweeping, 90% went into spontaneous labor compared to 75% of those who did not have the procedure.
  • Only 10% of those who received membrane sweeping were still pregnant at 41 weeks of gestation compared to 25% of those who did not.
  • Membrane sweeping did not affect the risk of maternal or fetal complications.

The Procedure

Doctors may perform a membrane sweep in their office or at the hospital. The process typically takes less than 10 minutes, and you don't have to do anything to prepare for the procedure.

Your doctor will first apply sterile gloves before performing 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.

The procedure can be uncomfortable but feels similar to having a Pap smear. It's worth noting that any sensation in the pelvic area is likely to feel more uncomfortable when you're at or near your due date.

Many people will report spotting or bleeding up to three days later. Others may experience mild cramping or have irregular contractions.

When to Call Your Doctor

It is essential to tell your doctor immediately if severe pain or heavy bleeding occurs during or after the membrane sweep.

How Safe Is Membrane Sweeping?

The sweeping of membranes carries a small risk of unintentionally rupturing the amniotic sac. However, the risks are considered relatively small for both the pregnant person and baby if performed by a qualified healthcare professional.

A 2019 review of research found no significant difference in the incidence of complications and that doing so reduced the need for other induction measures.

Who Should Not Have a Membrane Sweep?

A doctor is likely to decide against membrane sweeping in pregnant people who are showing signs of needing a cesarean delivery or who have a planned cesarean delivery. The following factors will also make the procedure unsuitable:

  • You have had a previous uterine rupture.
  • You have had previous uterine surgery such as fibroid removal.
  • You have a pregnancy complication called placenta previa, where the placenta covers the opening of the cervix.
  • You have other pregnancy complications that require a cesarean birth such as a breech presentation.

A Word From Verywell

Membrane sweeping is a low-risk procedure in uncomplicated pregnancies, and study results have shown that it can increase the likelihood of spontaneous labor. This procedure, although uncomfortable, may be an effective way to start labor without the use of medicines.

If you are past your due date and are not at risk of needing a surgical delivery, talk to your healthcare provider about membrane sweeping.

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Article Sources
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