Artificial Rupture of Membranes (Amniotomy) – Purpose, Procedure & Risks

When it’s time for your baby to arrive, your body will give you different signs to let you know that you’re ready for labour. One such sign is water breaking, or the rupturing of the amniotic sac.

However, the last stage of pregnancy may not be easy for all women, and you may find yourself asking a doctor to induce labour. Your doctor may consider artificially rupturing the sac in order to speed up labour. This method is known as amniotomy or ARM (Artificial Rupture of Membranes).

This procedure is used in several hospitals. Read on to learn when doctors may consider this procedure, whether there are any associated risks involved, and more.

What Is Meant By Amniotomy?

Amniotomy or artificial rupture of membranes is a procedure that is performed to rupture or break the water sac of a pregnant woman (1). This water sac or amniotic fluid is the liquid that protects and surrounds the baby in the pregnant woman’s uterus for nine months and as it breaks it releases hormones, which helps in sending signals to the brain for beginning or intensifying the labour (2). Approximately 10 per cent of pregnant women experience this phenomenon naturally, however, in some cases, the doctor or midwife may recommend doing it artificially, for the labour to progress. In simple words, amniotomy definition can be summed as ‘artificial rupturing of the amniotic sac’.

When Is Artificial Rupture of Membranes Performed?

Before amniotomy is considered as an option, your doctor will assess how much your cervix has opened up or dilated, how thin has the cervix is (effacement), how low the baby is in your cervix (fetal station) and various other such factors (3). After assessing all such factors, the doctor will calculate the likelihood of the procedure being successful. Some doctors may do so by Bishop’s score (or cervix score which is done to check if labour induction will be required) for amniotomy, where points are assigned to dilation, effacement, fetal station, consistency and position and based on the points the decision to conduct or not to conduct the procedure is taken (4).

Why Is Amniotomy Performed?

Here are some reasons when your doctor may consider inducing labour via amniotomy (5).

1. To Start Labor

Artificial rupturing of the membrane is a great way of inducing or starting the labour, especially if the cervix is favourable too.

2. For Augmentation of Labor

Amniotomy is a great way of speeding up the labour. But that may not be feasible in all cases, however, it may reduce the chances cesarean delivery.

3. For Foetal Monitoring

Amniotomy can be performed if your baby is in need of close fetal monitoring. This is usually done in cases when the labour is prolonged or it’s a high-risk delivery.

Is Amniotomy Painful?

Amniotomy is usually not considered painful, although it may feel uncomfortable for some women. During the procedure, the doctor or midwife uses a small sterile instrument to make a tiny opening in the amniotic sac so that the fluid can drain out. Since the sac itself does not contain nerves, the rupture is generally painless.

However, you may feel:

• Mild discomfort during the vaginal examination
• Pressure in the pelvic area
• Warm fluid flowing out once the water breaks

How Long Can the Procedure Take?

An amniotomy is a quick procedure and usually takes only a few minutes to perform. The actual rupturing of the membrane often takes less than a minute, though preparation and examination may take a little longer.

Other Procedures That Can Be Performed Along With Amniotomy

Here are some other procedures that can be performed along with amniotomy:

1. IV Oxytocin Drip

An IV oxytocin drip is a medication used for uterine contractions (6).

2. Cervical Ripening

Your doctor will perform this technique for softening and dilating the cervix. This will prepare the cervix for vaginal delivery (7).

3. Stimulating the Nipples

This procedure will help the body release natural oxytocin, which will be beneficial in stimulating contractions (8).

4. Stripping the Membrane

This procedure involves gently separating the amniotic sac from the uterus, which helps the body to release hormones to start the contractions.

Healthcare Providers Who Perform the Artificial Rupture of Membranes

Here are some healthcare providers that can perform amniotomy:

1. Midwives

These are the healthcare providers who offer prenatal, labour, and delivery care. However, certified professional midwives or CPM or Certified nurse-midwives CNM are the ones who usually perform amniotomy in some cases.

2. Family Medicine Doctor

These are the healthcare providers that provide help and assistance to adults, children and also may provide assistance during labour and childbirth.

3. OB/GYN Obstetrician/ Gynecologists

These are the healthcare providers who specialise in health care issues of women, pregnancy, labour, and childbirth.

Amniotomy vs Membrane Sweep

Amniotomy and a membrane sweep are both procedures used to encourage labour, but they work differently. A membrane sweep is a less invasive method in which a doctor or midwife gently separates the membranes around the baby from the cervix during a vaginal examination to help stimulate natural labour (9). An amniotomy, on the other hand, involves deliberately breaking the amniotic sac using a sterile instrument to induce or speed up labour. While a membrane sweep can be done during a routine prenatal visit, an amniotomy is usually performed in a hospital setting once labour induction is planned or labour has already begun.

Tips to Prepare for Amniotomy

Here are a few artificial rupture of membranes guidelines to help you prepare better:

• Start taking any medication that may be prescribed by your healthcare practitioner.
• Talk to your doctor in detail about your medical history, which includes telling about any OTC medications, vitamins, herbal medicines, etc. that you may be taking.
• Talk to your doctor about any decrease in fetal movement, vaginal discharge, contractions, cramps, bleeding, etc.

Questions to Ask Doctor About Amniotomy

Apart from helping your doctor by preparing for the procedure, you may also ask some questions that may help ease your worries:

• Why is this procedure considered and whether or not are there any other options that you may consider?
• How long after amniotomy does labour usually progress?
• Will I be prescribed any medicines before and after the procedure?
• What will happen when the sac gets ruptured?
• Are there any risks for my baby or me, in case I do not go in for the procedure?

Procedure of Amniotomy

A controlled artificial rupture of membranes is performed in the labour room and usually takes only a few minutes. Here is how the procedure is generally performed (1):

• You will be made to lie down on your back with your legs parted and bend.
• Your healthcare provider will use amniotomy equipment that includes a small hook or a gloved finger with a hook on its head, which will be inserted through your vagina and cervix to reach the uterus.
• This hook will pull the sac until it ruptures it.
• You will feel water coming out from your vagina.
• Your healthcare provider may check the fluid for any traces of meconium or fetal stool.
• If required, a device will be attached to monitor your baby’s heartbeat.

What to Expect After the Procedure

Your health practitioner and the care team will take the utmost care while performing the procedure as your comfort is of utmost importance. You are likely to wonder how will you feel after artificial rupturing of membranes. Well, you will feel warm down there as warm water will flow down from your vagina. You may also feel some pain in your lower back and may experience pain similar to that of menstrual cramps. It is normal to feel a slight discomfort in your cervix because of the amniotomy hook but pain during amniotomy is unusual. You should talk to your healthcare provider about the same.

You may notice that your contractions may become more intense after the procedure. If your contractions become intense, it’s a sign that amniotomy was successful. You can follow breathing techniques that you may have learned in your childbirth classes. If contractions intensify and you are unable to bear the pain, you can talk to your healthcare provider for pain-relieving options.

Risks and Complications of Artificial Rupture of the Membranes

Although amniotomy is generally considered safe, it is important to understand the possible amniotomy complications. Here are some risks that may arise after amniotomy (10):

• It may lead to vaginal bleeding.
• It may cause injury to the baby.
• It may cause infection to the mother or the baby.
• It may lead to umbilical cord prolapse, which may cut off the baby’s blood supply and lead to emergency cesarean delivery.
• It may lead to foetal distress.
• If the baby’s head is not fixed in the cervix, this procedure may sometimes lead to fetal malposition and thus cause complications in delivery.

How to Lower These Risks

Here are some effective ways of reducing the chances of any risks:

• Inform your doctor about any increase in pain or bleeding that you may register.
• Take prescribed medicines as suggested.
• Talk to your care team about the extent and type of your contractions that you may be experiencing.
• Follow a healthy diet and exercise as suggested by your healthcare team.
• Make sure that you get all the required prenatal care.

When Amniotomy Should Not Be Performed

Amniotomy is a fairly safe procedure, however, it may not be an ideal choice for intensifying or starting labour for all women. Your doctor may be able to establish the same during your second or third-trimester ultrasound scan or while performing a vaginal exam that this procedure may not be a safe bet for you. Here are some instances that your doctor may advise against this procedure:

1. If Baby’s Head Is Not Fixed

In case the baby’s head is in zero station or floating, this means that it is not fixed or engaged in the cervix. Under such a situation, your doctor may advise you against this procedure.

2. If the Baby Is in the Breech Position

If the baby is in a breech position that includes brow presentation or face presentation or in any other such malpresentation, your doctor may not recommend the procedure.

3. Vasa Previa

Vasa Previa is a condition when the blood vessels from the umbilical cord or placenta pass over the cervix beneath the foetus. This condition is usually detected during the routine ultrasound scans. In the case of vasa previa, the doctor may advise against amniotomy (11).

What Happens if Amniotomy Doesn’t Work?

In some cases, an amniotomy may not be enough to start or speed up labour effectively. If contractions do not become stronger or labour does not progress after the procedure, the doctor may recommend additional methods to induce labour. These may include medications such as oxytocin to stimulate contractions or other cervical ripening techniques.

Your healthcare team will continue to monitor both you and your baby closely to ensure everything remains safe. If labour still does not progress or if there are signs of distress, a Caesarean delivery may sometimes be considered (12). The outcome can vary depending on the mother’s condition, the baby’s health, and how the body responds to induction methods.

FAQs

1. Can amniotomy increase the chances of a C-section?

Amniotomy itself does not always increase the chances of a C-section, especially when labour progresses normally after the procedure. In many cases, it is performed to help speed up labour and support vaginal delivery. However, if complications arise, such as fetal distress, infection, or failure of labour to progress, a Caesarean section may become necessary.

2. Is amniotomy safe for all pregnancies?

Amniotomy is not considered suitable for all pregnancies. Doctors usually recommend the procedure only when they believe it is safe and beneficial for both the mother and the baby. It may not be advised in certain situations, such as placenta previa, abnormal fetal position, active infections, or when the baby’s head is not properly engaged in the pelvis.

3. Can amniotomy be done more than once?

No, amniotomy can only be performed once because the amniotic sac cannot be resealed after it has been ruptured. Once the water is broken, labour is expected to continue under medical supervision.

Amniotomy or artificial rupturing of membranes, like other medical procedures, has its own set of pros and cons. It is important that you discuss the drawbacks and benefits with your doctor before you consider this procedure to bring on (or to speed up) the labour.

Also Read: 

Failed Induction of Labour
Low Amniotic Fluid while Pregnant
Baby Born with Amniotic Sac
Ways to Increase and Decrease Amniotic Fluid during Pregnancy

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Sources References

1. Cleveland Clinic – Amniotomy

2. Cleveland Clinic – Amniotic Fluid

3. National Library of Medicine – Amniotomy

4. Cleveland Clinic – Bishop Score

5. ScienceDirect – Amniotomy

6. Cleveland Clinic – Oxytocin Injection

7. Cleveland Clinic – Cervical Ripening

8. PubMed Central – Breast stimulation for cervical ripening and induction of labour

9. Cleveland Clinic – Membrane Sweep

10. International Journal of Reproduction, Contraception, Obstetrics and Gynecology – Impact of planned amniotomy on perinatal outcome: a randomized control trial

11. Cleveland Clinic – Vasa Previa

12. American College of Obstetricians and Gynecologists – Labor Induction