What is an amniotomy?

An amniotomy, also known as artificial rupture of membranes (abbreviated AROM or ARM), is a procedure in which a woman’s amniotic membrane is ruptured prior to or during the labor process.


Amniotomy: Overview

The amniotic sac is a fluid-filled sac, composed of membranes, in which the fetus develops. Sometimes, the sac will spontaneously burst near the onset of labor. This is often referred to as the rupture of membranes (ROM), or, more colloquially, a woman’s “water breaking.” Other times, however, medical professionals with artificially rupture the amniotic membrane, using either a tool such as an Amnihook (which resembles a crochet hook) or Allis clamp (similar to a pair of scissors), or their own finger (using an Amnicot, which is a protective latex shield with a small hook on the end). 

Why Would an Amniotomy Be Performed?

There are several purported justifications for performing an amniotomy, including:

  • To induce labor
  • To augment a prolonged labor
  • To allow placement of internal monitors such as a fetal scalp electrode or intrauterine pressure catheter
  • To assess amniotic fluid (for the presence of meconium, for example) (1)

How Effective is Amniotomy?

There is conflicting evidence regarding the effectiveness of amniotomy in augmenting and inducing labor. Used in conjunction with the contraction-enhancing drug Pitocin, a synthetic form of the hormone oxytocin, amniotomy may help to induce or augment labor (1, 2). However, it is important to note that there are risks associated with both Pitocin and amniotomy. To learn more about complications arising from Pitocin use, click here. To learn more about the risks of amniotomy, continue reading. It has been suggested that amniotomy helps to hurry labor along because it increases circulating plasma prostaglandin concentrations, which promotes contractions (3). However, there is no compelling evidence that amniotomy alone can induce labor, shorten labor, or prevent C-sections (4). Other potential benefits of performing an amniotomy (namely, that it permits placement of internal monitors and assessment of amniotic fluid) must be weighed against the risks of this procedure in order to make an informed decision.

What Are the Risks Associated With Amniotomy?

Umbilical Cord Prolapse

Umbilical cord prolapse is a condition in which the umbilical cord emerges from the birth canal before or alongside the baby (as opposed to after the baby’s head has been delivered). The cord may become compressed between the baby’s head/presenting part and the cervix; if this happens, oxygen supply to the baby will be reduced or cut off, potentially resulting in serious conditions such as hypoxic-ischemic encephalopathy (HIE), cerebral palsy, and neonatal seizures. Cord prolapse often occurs when the membranes rupture. If they are ruptured artificially and labor is prolonged, then the window of time in which prolapse can occur is lengthened and the risk increases (1).

Infection

Once a woman’s membranes have ruptured, either via natural or artificial means, the fetus becomes vulnerable to infections that can ascend from the vagina into the uterus. This may lead to conditions such as placentitis and chorioamnionitis (which can result in lifelong disabilities if improperly handled). Amniotomy increases the risk of fetal infection because the procedure is not always successful at inducing or hastening labor, and there may be a prolonged period of vulnerability to infection. It is said that once a woman has an amniotomy, she is “committed to giving birth”; in other words, if she does not soon deliver vaginally or via Cesarean, then the baby may be in danger (1).

Fetal Scalp Trauma

Although the damage is usually minor, the fetal scalp may be scratched during an amniotomy, especially if the head is very close to the membranes and/or if the medical professional performing the procedure is not careful. One study found that use of an Amnicot reduced the risk of fetal trauma over that of an Amnihook (5).

When Should Amniotomy Be Avoided?

Sometimes, elective amniotomy is performed in women with normal labor progression. However, this is recommended against by both The Cochrane Collaboration and the American College of Obstetricians and Gynecologists (ACOG). A 2013 Cochrane review (4) found no evidence that amniotomy could shorten the first stage of labor. They did, however, observe a possible increase in the need for C-sections. Based in part on that Cochrane review, the American Congress of Obstetricians and Gynecologists (ACOG) also released a statement on routine amniotomy (6), saying that “for women with normally progressing labor and no evidence of fetal compromise, routine amniotomy need not be undertaken unless required to facilitate monitoring.”

Additionally, an amniotomy should not be performed if any of the following conditions are present:

  • The cervix is not dilated (opened) and effaced (thinned) (7)
  • The fetus’s presenting part is not yet engaged (but see “controlled amniotomy,” discussed in the next section)  (1)
  • The mother has an active infection, such as:
    • Human immunodeficiency virus (HIV)
    • Hepatitis B
    • Hepatitis C (8)
    • Herpes (1)
  • Vasa previa has been diagnosed or is suspected
  • Any reason why vaginal delivery is unsafe (for example, the baby is showing signs of fetal distress) (9)

How Should an Amniotomy Be Performed?

If an amniotomy IS indicated (usually to promote labor in conjunction with oxytocin, or because internal monitoring is necessary), there are certain steps that medical professionals must follow:

  1. Explain the procedure to the woman, including all risks and alternative options
  2. Obtain consent
  3. Check for the presence of any contraindications
  4. Put underpads underneath the woman to absorb the amniotic fluid
  5. Elevate the woman’s hips on something soft and sterile (such as a rolled-up towel or padded bedpan)
  6. Conduct a vaginal exam using sterile gloves and lubricant
  7. Perform the amniotomy procedure, using a sterile tool
  8. After the procedure, monitor fetal heart rate and pattern, amniotic fluid characteristics (color, odor, etc), and maternal temperature (for signs of infection) (1)

If an artificial rupture of membranes is performed in a woman with polyhydramnios (excessive amniotic fluid), or if the presenting part of the fetus has not yet engaged, it should be a “controlled amniotomy.” This means that it occurs in the operating room, in case an emergency C-section becomes necessary (medical personnel should always be prepared to perform an emergency C-section after an amniotomy, but especially in these cases). A controlled amniotomy is also done using a small gauge needle instead of a hook, as this can allow the fluid to drain more slowly (8).

Legal Help for Birth Injuries Due to Contraindicated or Mismanaged Amniotomy

Medical professionals should know that there are risks involved in artificially rupturing the amniotic sac, and that this should only be done if it is medically necessary. In other words, an amniotomy should not be performed for purely elective reasons. If you had an amniotomy that you believe was contraindicated or mismanaged, and your child has a birth injury/serious infection, you may be eligible for compensation. At Reiter & Walsh ABC Law Centers, we consult closely with leading medical experts, forensic specialists, and life care-planning professionals to secure our clients’ future care and their parents’ peace of mind, knowing their child will be cared for, no matter what. Our specific focus on birth injury allows our attorneys to provide unparalleled legal service to our clients. To begin your free case review, please contact Reiter & Walsh ABC Law Centers in any of the following ways:

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Sources

  1. Wong HW, Perry L. Maternal Child Nursing Care. 2006
  2. Amniotomy plus intravenous oxytocin for induction of labour
  3. Rapid increases in plasma prostaglandin concentrations after vaginal examination and amniotomy
  4. Amniotomy for shortening spontaneous labour
  5. Amnihook versus amnicot for amniotomy in labour
  6. Approaches to Limit Intervention During Labor and Birth
  7. Amniotomy alone for induction of labour
  8. Management of normal labor and delivery
  9. Amniotomy