Amniotomy

What is an amniotomy?

An amniotomy or artificial rupture of membranes (AROM), is a procedure to break your amniotic sac. An amniotic sac (or bag of waters) is a fluid-filled sac that surrounds the fetus during pregnancy. Your amniotic sac contains liquid called amniotic fluid. Amniotic fluid protects and cushions the fetus and softens its movements while in the uterus.

When it’s time for your baby to be born, the amniotic sac ruptures, and amniotic fluid comes out. This happens naturally as labor contractions progress for some people. However, for others, the amniotic sac doesn’t break despite being in labor. Therefore, your healthcare provider may recommend amniotomy to intentionally break your water.

Rupturing or breaking your amniotic sac can cause your uterus to contract and help dilate your cervix.

Why is an amniotomy performed?

In most cases, your healthcare provider performs an amniotomy to speed up your labor. There are risks associated with AROM, and it may not be ideal for everyone. Reasons for AROM are:

• To advance or induce labor: Rupturing the membranes may release hormones that cause stronger contractions. Without the cushioning of amniotic fluid, your baby can move down deeper into the pelvis. This pressure on your cervix may cause further dilation.
• To monitor your baby more closely: Your healthcare provider may want to use an internal fetal monitor to watch your baby’s heart rate. A monitor placed on your baby’s head gives a more reliable reading than an external monitor.
• To examine amniotic fluid: Passing too much meconium (your baby’s first poop) can affect your baby’s health. Checking your amniotic fluid for meconium helps your provider plan for suctioning your baby’s nose and mouth right after delivery.

The effectiveness of AROM is often debated by healthcare providers and medical researchers. Some studies show that it doesn’t necessarily advance labor in low-risk pregnancies and that a natural labor progression is preferred. However, some data shows that it can speed up labor.

How is an amniotomy performed?

First, your healthcare provider will evaluate your cervix to see if it’s softened or thinned and if your baby’s head is in the correct position. Your baby should be low in your pelvis and pressed against your cervix. Next, your healthcare provider will place pads or towels under you to absorb the fluid from the amniotic sac once it's broken.

A thin, plastic tool called an amnihook ruptures your membranes. An amnihook is about 12 inches long with a curved hook at the top. It resembles a hook you’d use to crotchet a blanket. To break your water, your healthcare provider inserts the amnihook through your vagina. Once they find the bag of water or amniotic sac, they scratch or tear a hole in it to allow the fluid to escape.

How do I prepare for an amniotomy?

You don’t need to prepare for an amniotomy. Be sure to discuss any concerns you have about the procedure with your healthcare provider.

What happens after your doctor breaks your water?

You may see either a gush or a trickle of fluid from your vagina. Your healthcare provider will use several absorbent pads or towels to soak up the fluid. You may feel more intense contractions that come closer together. If the procedure is successful, your healthcare provider may tell you that your cervix is dilating more quickly.

Does it hurt when your doctor artificially ruptures your membranes?

Most people don’t feel anything, especially if you are already in labor or got an epidural to manage painful contractions. Your baby also doesn’t feel an amniotomy, and it doesn’t hurt them in any way. People who haven’t taken any pain medication may feel slight discomfort when the amnihook is inserted.

What are the advantages of an amniotomy?

The advantages of having your water intentionally broken are:

• It can speed up or progress your labor by bringing your baby down closer to your cervix and increasing contractions.
• It can help your healthcare provider monitor your baby more closely for distress.
• It can help detect meconium levels and determine what kind of medical support your baby needs at delivery.

What are the risks or complications of an amniotomy?

There’s no guarantee that an amniotomy will shorten your labor or cause your labor to speed up. Complications of an amniotomy may include:

• Umbilical cord prolapse: A cord prolapse is when the umbilical cord drops through the vagina before your baby. This can cut off your baby’s oxygen supply.
• Umbilical cord compression: This is when the umbilical cord is flattened and restricts your baby’s oxygen supply.
• Cesarean delivery: You may be at an increased risk for C-section because your baby is in a breech position after the amniotic sac is ruptured.
• Infection: Without amniotic fluid, your baby doesn’t have protection from infections. Your baby’s risk of infection increases the longer it takes between your water breaking and delivery.
• Increased pain: Some people feel more intense contractions and increased pain after AROM. Once the cushioning of amniotic fluid is gone, there’s no padding between your baby’s head and your cervix.

When is it not safe to artificially rupture the membranes?

It’s unsafe to have your water broken if:

• Your baby isn’t headfirst in the birth canal.
• Your baby’s head hasn’t descended into your pelvis. This positioning is your baby’s fetal station. A fetal station of 0 is suggested before AROM.
• Your cervix isn’t "favorable." A favorable cervix is soft, thin and open (dilated).
• You have vasa previa. This is when blood vessels cross over the cervix. It can be life-threatening for your baby.

Does an amniotomy always speed up labor?

Not always. Healthcare providers have mixed feelings about the benefits of amniotomy. Some studies show it can shorten labor by about an hour. Other evidence shows that intervening with labor isn’t effective, and the risks may outweigh the benefits in an otherwise healthy pregnancy. You and your healthcare provider will make the best decision based on your pregnancy and your medical history. It’s always good to be informed so you feel comfortable with your options.

A note from Cleveland Clinic

An amniotomy can speed up labor during delivery. Every pregnancy is different, and there’s no guarantee an amniotomy will progress your labor. In some cases, your medical history or stage of labor can make this procedure dangerous. Make sure you understand the risks and benefits of artificially rupturing your membranes. Being informed about the procedure will help you feel confident that it’s the safest and healthiest decision for your baby.