Overview of Amniotomy
An amniotomy, often referred to as “breaking the water,” is a medical procedure where your obstetrician (the doctor who takes care of you during your pregnancy) intentionally ruptures, or opens, the amniotic sac. The amniotic sac is the bag of fluid inside the womb, where your baby develops.
This procedure has been used during childbirth for hundreds of years and it’s usually done to make your labor progress faster. It can also help the doctor monitor your baby more directly and assess the health of the amniotic fluid (the liquid that surrounds and protects your baby in the womb).
Remember, not every woman will need an amniotomy during labor, and your obstetrician will discuss all your options with you to decide what’s best in your situation.
Anatomy and Physiology of Amniotomy
The amniotic cavity is a special area inside the womb where a baby grows and is kept safe while it’s in the mother’s body before birth. It’s made up of two layers: the inner layer, called the amnion, and the outer layer, called the chorion. Quite early in pregnancy, this space starts to fill up with a liquid known as serous fluid. As the baby (or fetus) develops further and its urinary system starts to work, this space fills up even more because the baby is passing urine, which makes up most of the amniotic fluid.
Normally, this protective barrier stays in place for the whole pregnancy. When it’s time for the baby to be born, these layers will break on their own, and the amniotic fluid is released. This may happen just before a mother goes into labor naturally, or sometimes it happens after labor has already started.
Why do People Need Amniotomy
There are two main reasons why a doctor might need to purposely break a woman’s water (or rupture her amniotic membrane) during labor. The first reason is to either get the labor started or to speed it up. The second reason is to place special monitoring devices on the baby that help doctors track the baby’s health during labor.
Typically, doctors can monitor the baby’s heartbeat and the mother’s contractions from outside the mother’s body. But in some cases, they might need a more accurate picture of what’s going on. That’s where the special monitoring devices come in. To get these devices on the baby, the doctor needs to break the mother’s water because the amniotic membrane is in the way.
These devices might include a fetal scalp electrode, which is attached to the baby’s scalp to monitor its heartbeat, or an intrauterine pressure catheter, which measures the pressure inside the uterus to understand how strong the contractions are. Both are used to make sure that the baby is doing well during labor and delivery.
When a Person Should Avoid Amniotomy
There are only a few clear cases when we should not do a procedure known as artificial rupture of membranes. This is a method to induce labor by breaking the water bag. However, it’s not suitable for all situations. For example, if the baby is not positioned correctly in the womb (malpresentation), or if the blood vessels of the baby’s umbilical cord are abnormally placed in the womb (vasa previa), or if the umbilical cord is attaching in an unusual way (suspected velamentous insertion), this method should not be used.
It’s also not recommended if the baby’s head is not properly settled into the mother’s pelvis (unengaged fetal head) or if the baby’s position keeps changing (unstable lie). Both these situations can increase the risk of the umbilical cord slipping out before the baby does, which is called cord prolapse.
Also, this method is not suitable if the mother is not yet in active labor, or if the mother doesn’t consent to this process.
Equipment used for Amniotomy
An amniotomy hook or an amniotomy finger cot are used during the procedure. These tools help break the water (amniotic sac) during labor.
You’ll notice that the doctor will be wearing sterile gloves along with a lubricant to ensure a safe procedure without any infection risks.
As part of safety measures, personal protective equipment such as gloves, gown, drapes, mask, and eye protection are worn by your healthcare provider during the procedure.
For your comfort and to maintain cleanliness, absorbent pads and towels will be placed under you.
A device known as an electronic fetal monitor will be used. This monitors your baby’s heartbeat (also termed as cardiotocography or CTG) during the procedure.
Tocolytics, medications that may help slow or stop labor contractions, should be within reach if needed.
Who is needed to perform Amniotomy?
Three main medical professionals usually help during childbirth. There is the doctor, who could be an obstetrician (a doctor who specializes in pregnancy, childbirth, and a woman’s reproductive system) or sometimes a family medicine physician who also has training in prenatal care and childbirth.
Another professional often present is a midwife. A midwife is a trained health professional who helps healthy women during labor, delivery, and after the birth of their babies. Midwives may deliver babies at birthing centers or at home, but most can also deliver babies at a hospital.
Finally, there is a labor and delivery nurse, who assists the doctor and midwife, and also provides support and monitoring to you during all parts of labor and delivery.
Preparing for Amniotomy
An amniotomy, or breaking of the mother’s water, is an easy process that’s done with specific tools designed to carefully break the membrane that holds the amniotic fluid. The two instruments most commonly used are a rod about 10 inches long with a hook on one end, or a protective finger cover with a hook at its end. With either tool, the doctor will first check how much the mother’s cervix has opened using a clean, glove-covered finger. During this check, the doctor also determines the position of the baby’s head to be sure it’s the part of the baby that’s moving down into the birth canal first and that it’s optimally positioned in the pelvis. With the baby’s position and engagement in mind, and after confirming these factors, the doctor can go ahead with the procedure to intentionally break the amniotic sac.
How is Amniotomy performed
When a rod-hook device is utilized, it’s typically held outside of the vagina with the non-dominant hand. The hooked end is carefully protected between two fingers as it’s inserted into the vagina. Once the doctor can physically feel the water-filled sac (the amniotic membrane) and the baby’s presenting part, they gradually move the hook to the amniotic membrane. The hook gently catches onto the membrane, before subtly pulling it upward to tear the membrane and release the fluids.
This process, known as an artificial rupture of membranes, is often confirmed by the immediate discharge of fluid from the vagina. Normally, this fluid is clear and doesn’t have an odor. However, under certain conditions, it may contain the baby’s first stool (meconium) or have traces of blood. It is crucial for the doctor to note the color of the fluid when it breaks.
After the artificial rupture of membranes takes place, it’s important for the doctor to keep their hand in the vagina for a short while. This is the moment when there is the greatest risk of the umbilical cord slipping down into the vagina before the baby (also known as a cord prolapse), which can be detected as the amniotic fluid continues to flow out. Doctors will check for this and if no cord is found and the initial discharge of fluid from the vagina has slowed down, they can then safely remove their hand.
Possible Complications of Amniotomy
There aren’t usually many complications when a doctor artificially ruptures a woman’s membranes to start or speed up labor. However, when the protective barrier around the baby (the membrane) is broken, this does expose the baby to the various germs found in the vagina.
If this procedure is done too early in labor, it might increase the chance of an infection in the uterus during delivery, known as chorioamnionitis.
The most common issue when breaking the waters artificially is that the umbilical cord, which provides the baby with nutrients, can slip down into the birth canal ahead of the baby. This is most likely to happen if the baby’s head isn’t firmly in the mother’s pelvis when the membranes are ruptured.
The problem here is that when the baby’s head pushes down, it could squeeze the cord and slow down the baby’s heartbeat, requiring an emergency c-section. This is a complication that doctors aim to avoid since it requires an immediate delivery of the baby for safety reasons.
What Else Should I Know About Amniotomy?
Some medical professionals think that breaking the bag of water (also known as the amniotic sac) surrounding the baby can help labor start or make it go faster. They believe that removing the amniotic fluid, which houses the baby, can make the womb contract more, make contractions stronger, and help open the cervix for delivery. This belief is based on the idea that the baby’s head can directly press on the cervix without the cushioning effect of the amniotic sac, which can help widen the cervix.
Despite these widespread beliefs, there is conflicting evidence to support them. Some studies have found that breaking the bag of water can help with labor, while others have found it doesn’t make any significant difference. Research reviews that combine the results of various studies (called meta-analysis) have been conducted to offer a clearer picture. However, they’ve also produced mixed findings.
According to these reviews, there is no clear indication that breaking the bag of water makes labor shorter compared to not doing it. But, they suggest that when labor is taking longer than usual, breaking the water bag, especially when used combined with a hormone called oxytocin, could slightly decrease the chance of needing a cesarean section (or C-section), which is a surgery to deliver the baby.