Tag Archives: spontaneous uterine rupture

Myth: VBACs should never be induced

Note: When I refer to a spontaneous labor, I mean a non-induced/augmented labor. Also, given that the risk of rupture increases with induction, a hospital is the best location for an induction.


Many of the comments left at the Forced Cesarean mom story questioned the safety of inducing a VBAC mom. Many people believe that is it excessively dangerous and that VBACs should never been induced or augmented. This is just not the case.

Spontaneous labor is always preferable to induced or augmented labor but there are medical conditions that can necessitate the immediate birth of a baby. It’s nice for those women for whom vaginal birth is still an option to have a choice: gentle induction/ augmentation or repeat cesarean. Of course, reviewing the risks and benefits of available options, including doing nothing, is essential. Some women might be more comfortable scheduling a cesarean whereas others might want to give a gentle Pitocin and/or Foley catheter induction a go.

ACOG’s stance on inducing VBACs

The latest 2010 VBAC Practice Bulletin No. 115 produced by the American Congress of Obstetricians & Gynecologists (ACOG) asserts:

Induction of labor for maternal or fetal indications remains an option in women undergoing TOLAC [trial of labor after cesarean]… However, the potential increased risk of uterine rupture associated with any induction, and the potential decreased possibility of achieving VBAC, should be discussed… Misoprostol [Cytotec] should not be used for third trimester cervical ripening or labor induction in patients who have had a cesarean delivery or major uterine surgery.

Stuart Fischbein MD, a vaginal breech/twins and VBAC supportive Southern California OB, recently shared this on my Facebook page,

According to ACOG, prior low transverse c/section is not a contraindication to induction (other than the use of Misoprostol [Cytotec]) so a Foley balloon or Pitocin may be used safely in these women. The problem arises when a practitioner does not believe in doing inductions on women with prior c/section. Despite the evidence and the ACOG clinical guideline the reality is that many doctors will just not want to deal with it.

“Many doctors will just not want to deal with it” for a variety of reasons including experiencing a recent uterine rupture or lawsuit and pressure from hospital administrators or other OBs in their practice. It’s good to know from the beginning if your care provider is open to a gentle VBAC induction and under what conditions they would recommend induction. (See below for the Mayo Clinic’s reasons for induction.) This is why I suggest asking care providers when you first meet with them: “Under what circumstances would you induce a VBAC?” and “What induction methods do you use?”

Medical reasons for induction

While many women are induced for non-medical reasons, such as being pregnant for 40 weeks and one day, there are many medical conditions where induction is a reasonable option. According to the Mayo Clinic’s article Inducing labor: when to wait, when to induce dated July 23, 2011:

Your health care provider might recommend inducing labor for various reasons, primarily when there’s concern for your health or your baby’s health. For example:

  • You’re approaching two weeks beyond your due date, and labor hasn’t started naturally
  • Your water has broken, but you’re not having contractions
  • There’s an infection in your uterus
  • Your baby has stopped growing at the expected pace
  • There’s not enough amniotic fluid surrounding the baby (oligohydramnios)
  • Your placenta has begun to deteriorate
  • The placenta peels away from the inner wall of the uterus before delivery — either partially or completely (placental abruption)
  • You have a medical condition that might put you or your baby at risk, such as high blood pressure or diabetes

ACOG’s 2009 recommendations on induction lists the following reasons:

  • Abruptio placentae [placental abruption]
  • Chorioamnionitis [infection in your uterus]
  • Fetal demise [baby has passed away]
  • Gestational hypertension
  • Preeclampsia, eclampsia
  • Premature rupture of membranes
  • Postterm pregnancy [after 42 weeks]
  • Maternal medical conditions (eg, diabetes, mellitus, renal [kidney] disease, chronic pulmonary disease, chronic hypertension, antiphospholipid syndrome)
  • Fetal compromise (eg, severe fetal growth restriction, isoimmunization, oligohydramnios)

Big babies & going overdue

ACOG’s latest VBAC Pratice Bulletin No. 115 states that going over 40 weeks or suspecting a “big baby” should not prevent a woman from planning a VBAC. I suggest asking your care provider at your first appointment about what they would recommend doing if you go past 40 weeks, past 42 weeks, or if they believe your baby is large. They may suggest a cesarean, a gentle induction, or they be open to waiting for spontaneous labor. Then you decide how you feel about their answer. If you decide that their answer is not a good fit for you, you can weigh that against the responses of other VBAC supportive care providers in your area.

Uterine rupture rates in induced/augmented labors

There are two primary factors when looking at uterine rupture during an induction: the drug and the dose. Keep in mind that while the risk of rupture generally increases as the dosage increases, two women can respond very differently to the same dose of the same drug. According to JHP Pharmaceuticals, LLC, the manufacturer of Pitocin,

Oxytocin has specific receptors in the myometrium and the receptor concentration increases greatly during pregnancy, reaching a maximum in early labor at term. The response to a given dose of oxytocin is very individualized and depends on the sensitivity of the uterus, which is determined by the oxytocin receptor concentration.

Additionally, they assert that Pitocin should not be used for induction without medical indication:

Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, Pitocin is not indicated for elective induction of labor.

Many women point to the fact that the Pitocin drug insert states, “Except in unusual circumstances, oxytocin should not be administered in the following conditions” and then lists “previous major surgery on the cervix or uterus including cesarean section.” However, a prior cesarean is not listed under contraindications and the drug insert is clear:

The decision [to use Pitocin in a woman with a prior cesarean] can be made only by carefully weighing the potential benefits which oxytocin can provide in a given case against rare but definite potential for the drug to produce hypertonicity or tetanic spasm.

The elevated risk of rupture due to induction has been documented in several studies. Landon (2004) found that spontaneous labors had a 0.4% rate of rupture. That increased 2.5 times for induced labors (1.0%) and 2.25 times for augmented labors (0.9%).

Landon further broke out rupture rates by type of induction:

  • 1.4% (N = 13) with any prostaglandins (with or without oxytocin)
  • 0% with prostaglandins alone
  • 0.9% (n = 15) with no prostaglandins (includes mechanical dilation with a foley catheter with or without oxytocin), and
  • 1.1% (N = 20) with oxytocin alone.

Overall, they found 0.7% of women experienced an uterine rupture with an additional 0.7% experiencing a dehiscence.

Landon (2004) did a great job in providing rates of rupture per drug, but we don’t know the dose used in the induced/ augmented labors that ruptured versus those that didn’t rupture.

ACOG quotes a couple studies in their 2010 VBAC Practice Bulletin (emphasis mine):

One study of 20,095 women who had undergone prior cesarean delivery (81) found a rate of uterine rupture of 0.52% for spontaneous labor, 0.77% for labor induced without prostaglandins, and 2.24% for prostaglandin induced labor. This study was limited by reliance on the International Classification of Diseases, 9th Revision coding for diagnosis of uterine rupture and the inability to determine whether prostaglandin use itself or the context of its use (eg, unfavorable cervix, need for multiple induction agents) was associated with uterine rupture.

In a multicenter study of 33,699 women undergoing TOLAC, augmentation or induction of labor also was associated with an increased risk of uterine rupture compared with spontaneous labor (0.4 % for spontaneous labor, 0.9% for augmented labor, 1.1% for oxytocin alone, and 1.4% for induction with prostaglandins with or without oxytocin) (4). A secondary analysis of 11,778 women from this study with one prior low transverse cesarean delivery showed an increase in uterine rupture only in women undergoing induction who had no prior vaginal delivery (1.5% versus 0.8%, P=.02). Additionally, uterine rupture was no more likely to occur when labor induction was initiated with an unfavorable cervix than with a favorable cervix (91). Another secondary analysis examined the association between maximum oxytocin dose and the risk of uterine rupture (94). They noted a dose response effect with increasing risk of uterine rupture with higher maximum doses of oxytocin. Because studies have not identified a clear threshold for rupture, an upper limit for oxytocin dosing with TOLAC has not been established.

Induced labor is less likely to result in VBAC than spontaneous labor (44, 47, 92, 99). There is some evidence that this is the case regardless of whether the cervix is favorable or unfavorable, although an unfavorable cervix decreases the chance of success to the greatest extent (91, 100, 101). These factors may affect patient and health care provider decisions as they consider the risks and benefits of TOLAC associated with labor induction.

Given the lack of compelling data suggesting increased risk with mechanical dilation and transcervical catheters, such interventions may be an option for TOLAC candidates with an unfavorable cervix.

The Guise 2010 Evidence Report is another excellent resource that reviewed VBAC research published to date. It talks extensively about uterine rupture in induced births on pages 58 – 69 and concluded (emphasis mine):

The strength of evidence on the risk of uterine rupture with pharmacologic IOL [induction of labor] methods was low due to lack of precision in estimates and inconsistency in findings. The overall risk of rupture with any IOL method at term was 1.5 percent [1 in 67] and 1.0 percent [1 in 100] when any GA [gestational age] is considered. Among women with GA greater than 40 weeks, the rate was highest at 3.2 percent [1 in 31]. Evaluation of the evidence on specific methods of IOL reveal that the lowest rate occurs with oxytocin [Pitocin] at 1.1 percent [1 in 91], then PGE2 [prostaglandin E2] at 2 percent [1 in 50], and the highest rate with misoprostol [Cytotec] at 6 percent [1 in 17]. These findings should be interpreted with caution as there was imprecision and inconsistency in the results among these studies. The risk of uterine rupture with mechanical methods of IOL is understudied. Other harms were inadequately reported to make conclusions. Relative to women with spontaneous labor, there was no increase in risk of rupture among those induced at term. However, the available evidence on women with induced labor after 40 weeks GA indicates an increased risk compared with spontaneous labor (risk difference 1.8 percent; 95 percent CI: 0.1 to 3.5 percent). The NNH [number needed to harm] in this group is 56 (for every 56 women greater than 40 weeks GA with IOL during a TOL [trial of labor], one additional rupture will occur compared with having spontaneous labor).

So the bottom line is: more large, good quality studies that control for induction are needed.

What is too risky?

As ACOG (2010) states in their latest Practice Bulletin:

Respect for patient autonomy supports the concept that patients should be allowed to accept increased levels of risk, however, patients should be clearly informed of such potential increase in risk and management alternatives.

I agree and believe that each individual woman has the right to informed consent and, together with her care provider, can make the best decision for her individual situation. I think it’s hard to argue that women seeking VBA2C, home birth, or unassisted birth should have the right to accept the elevated levels of risk that come with those decisions and yet say that the elevated risk that comes with induced VBACs is unacceptable.

Keep in mind that while the risk of rupture is higher in an induced VBAC, the risk is similar to the risk of rupture in a VBA2C (0.9% per Landon 2006). So it’s hard for one to support VBA2C and yet demonize a VBA1C induced for medical indication by saying the risk of rupture is to high.

It is also important to note that 90 out of 91 Pitocin induced TOLACs do not rupture (Landon, 2004 & Guise, 2010). So while the risk is generally higher in induced/ augmented labors, the overall risk is still low and occurs at a rate comparable to other obstetrical emergencies.

Myth: Most ruptures occur in induced/augmented labors

It’s imperative that women seeking VBAC understand that the single factor that increases their risk of uterine rupture the most is their prior cesarean section. And while having your labor induced/augmented does increase your risk of rupture, please do not believe the myth that a spontaneous labor provides complete protection from uterine rupture.

To disprove this myth, I direct you to “the largest prospective report of uterine rupture in women without a previous cesarean in a Western country” which found that most ruptures occur in spontaneous labors (Zwart, 2009). Zwart differentiated between uterine rupture and dehiscence and found (emphasis mine):

of the 208 scarred and unscarred uterine ruptures, 130 (62.5%) occurred during spontaneous labor reflecting 72% of scarred ruptures and 56% of unscarred ruptures.

It is interesting to note that 16% of unscarred ruptures (representing 4 unscarred women) and 9% of scarred ruptures (representing 16 scarred women) happened before the onset of labor (Zwart, 2009).

What I would do

If there was a medical reason for my baby to born (as detailed by the Mayo Clinic above), and it was the difference between a VBAC and a repeat cesarean, and I had a favorable Bishop’s score (download the app), I would consent to a foley catheter and/or low-dose Pitocin induction (not Cytotec or Cervidil).

If I was induced or augmented with Pitocin, I would be comfortable with continuous external fetal monitoring. Some hospitals do offer telemetry which is wireless monitoring giving you more freedom of movement. I’ve even seen telemetry in tube tops (naturally I can’t find a link to it now, if you have a link, can you leave a comment?) and units that can be worn in birth tubs. It’s good to call the hospital beforehand to determine what kind of telemetry monitoring units they offer and to confirm that it’s not lost in a closet.

Final thoughts

There is no doubt that Pitocin is overused in America and often results in unnecessary emergency cesareans. However, it’s important not to cloud the two issues: medically unnecessary inductions and inductions with medical indication. There are situations where induction/ augmentation are reasonable and can give the mom one last option before having a cesarean. Thankfully, a low-dose Pitocin and/or foley catheter induction “remains an option” in women planning a VBAC according to ACOG. I think that is a good thing.

Further reading

Confusing fact: Only 6% of uterine ruptures are catastrophic

It is important to note that the information shared in Guise (2010), the 400 page Evidence Report on which the 2010 NIH VBAC Conference was based, collected the best data we have available on trial of labor after cesarean.  That said, they reported, “Overall, the strength of evidence on perinatal mortality was low to moderate” due to the wide range of perinatal mortality rates reported by the studies included in the report.  Bottom line: We still don’t have an accurate idea of how deadly uterine rupture is to babies.  This is a topic on which Guise recommended future researchers focus.  I highly recommend that anyone interested in TOLAC (trial of labor after cesarean), especially those who blog or share information on social networking sites, review this very important document as it is a fascinating analysis of the best research we have to date on TOLAC.

How many times have you heard, “Only 6% of uterine ruptures are catastrophic” or “Uterine rupture not only happens less that one percent of the time, but the vast majority of ruptures are non-catastrophic?” But what does that mean? Does that mean only 6% of uterine ruptures are “complete” ruptures? Result in maternal death? Infant death? Serious injury to mom or baby? This article will explain to you the difference between uterine rupture and uterine dehiscence as well as explain the source and meaning of the 6% statistic.

Distinguishing between uterine rupture and uterine dehiscence

First, it’s important to understand what a uterine rupture is and how that differs from a uterine dehiscence. Uterine rupture, also called true, complete, or even (to further add to the confusion) catastrophic rupture, is a opening through all the layers of the uterus. Per a Medscape article on Uterine Rupture in Pregnancy:

Uterine rupture is defined as a full-thickness separation of the uterine wall and the overlying serosa. Uterine rupture is associated with (1) clinically significant uterine bleeding; (2) fetal distress; (3) expulsion or protrusion of the fetus, placenta, or both into the abdominal cavity; and (4) the need for prompt cesarean delivery and uterine repair or hysterectomy.

Whereas a uterine dehiscence, also called a incomplete rupture or a uterine window, is not a full-thickness separation. It’s often asymptomatic, does not pose any risk to mom or baby, and does not require repair. Again, I refer to Medscape:

Uterine scar dehiscence is a more common event that seldom results in major maternal or fetal complications. By definition, uterine scar dehiscence constitutes separation of a preexisting scar that does not disrupt the overlying visceral peritoneum (uterine serosa) and that does not significantly bleed from its edges. In addition, the fetus, placenta, and umbilical cord must be contained within the uterine cavity, without a need for cesarean delivery due to fetal distress.

When reading medical studies, look for how they define uterine rupture in the “Methods” section. While some medical studies combine the statistics for rupture and dehiscence, ultimately reporting an inflated rate of rupture, other studies distinguish between the two events.

So, what does the 6% statistic mean and where did it come from?

The statistic “Only 6% of uterine ruptures are catastrophic” is from the Evidence Report (Guise 2010) which was the basis of the 2010 NIH VBAC Conference and it refers to the rate of infant death due to uterine rupture. Here is the exact quote:

The overall risk of perinatal death due to uterine rupture was 6.2 percent. The two studies of women delivering at term that reported perinatal death rates report that 0 to 2.8 percent of all uterine ruptures resulted in a perinatal death (Guise 2010).

In other words, of the women who had uterine ruptures, 6.2% (1 in 16) resulted in infant deaths. When we limited the data to women delivering at term, as opposed to babies of all gestational ages, the risk was as high as 2.8 (1 in 36)%.

When we look at the overall risk of an infant death during a trial of labor after cesarean, the NIH reported the rate of 0.13%, which works out to be one infant death per 769 trials of labor.

The source of the confusion

The problem with this statistic is that some people have misinterpreted it to mean that only 6% of ruptures are true, complete uterine ruptures. In other words, if we take the 0.4% (1 in 240) uterine rupture rate (Landon, 2004), they believe that only 6% of those ruptures or 0.024% (1 in 4166) are true, complete ruptures. This is false. The 0.4% uterine rupture statistic measured true, complete, uterine ruptures in spontaneous labors after one prior low, transverse (“bikini cut”) cesarean.

So how many dehiscences did Landon (2004) detect? Landon reported a 0.7% uterine rupture rate and a 0.7% dehiscence rate. (Note that these statistics include a variety of scar types as well spontaneous, augmented, and induced labors.) So Landon found that dehiscence occurs at the same rate as uterine rupture.

I think the best way to avoid confusion is to use very clear language: 6.2% (1 in 16) of uterine ruptures result in an infant death. Put another way, for every 16 uterine ruptures, there will be one baby that dies.

Elapsed time and infant death

What determines if a baby dies or has brain damage? Some research on infant cord blood gases has suggested that if the baby isn’t delivered (almost always by CS) within 16 – 17 minutes of a uterine rupture, there can be serious brain damage or death to baby. You can watch a presentation from the 2010 NIH VBAC Conference entitled “The Immediately Available Physician Standard” by Howard Minkoff, M.D. for more information or read his presentation abstract.

Now you know the difference between uterine rupture, uterine dehiscence and the meaning of the 6% statistic. It’s helpful to understand the terminology used in relation to uterine rupture otherwise it can be very confusing as you wade your way through the statistics! It’s also very important for people to use specific words whose definitions are clear instead of words such as “catastrophic” that could mean multiple things.

Afterward – The big picture

The following are excerpts from the Evidence Report (Guise 2010) , the 400 page evidence report assembled for the 2010 NIH VBAC Conference. The limitation of Guise (2010) is that these stats are for all VBACs – all scar types, multiple prior cesareans, induced/augmented labors, etc. It would have been helpful if they had broke out the data in these ways.

While rare for both TOL [trial of labor] and ERCD [elective repeat cesarean delivery], maternal mortality was significantly increased for ERCD at 13.4 per 100,000 versus 3.8 per 100,000 for TOL. The rates of maternal hysterectomy, hemorrhage, and transfusions did not differ significantly between TOL and ERCD. The rate of uterine rupture for all women with prior cesarean is 3 per 1,000 and the risk was significantly increased with TOL (4.7 1,000 versus 0.3 1,000 ERCD). Six percent of uterine ruptures were associated with perinatal death.” Perinatal death due to UR from term studies was 2.8%. “Perinatal mortality was significantly increased for TOL at 1.3 per 1,000 versus 0.5 per 1,000 for ERCD… VBAC is a reasonable and safe choice for the majority of women with prior cesarean. Moreover, there is emerging evidence of serious harms relating to multiple cesareans… The occurrence of maternal and infant mortality for women with prior cesarean is not significantly elevated when compared with national rates overall of mortality in childbirth. The majority of women who have TOL will have a VBAC, and they and their infants will be healthy. However, there is a minority of women who will suffer serious adverse consequences of both TOL and ERCD. While TOL rates have decreased over the last decade, VBAC rates and adverse outcomes have not changed suggesting that the reduction is not reflecting improved patient selection.

A systematic review strives to be patient-centered and to provide both patients and clinicians with meaningful numbers or estimates so they can make informed decisions. Often, however, the data do not allow a direct estimate to calculate the numbers that people desire such as the number of cesareans needed to avoid one uterine rupture related death. The assumptions that are required to make such estimates from the available data introduce additional uncertainty that cannot be quantified. If we make a simplistic assumption that 6 percent of all uterine ruptures result in perinatal death (as found from the summary estimate), the range of estimated numbers of cesareans needed to be performed to prevent one uterine rupture related perinatal death would be 2,400 from the largest study,204 and 3,900-6,100 from the other three studies of uterine rupture for TOL and ERCD.10, 97, 205 Taken in aggregate, the evidence suggests that the approximate risks and benefits that would be expected for a hypothetical group of 100,000 women at term gestational age (GA) who plan VBAC rather than ERCD include: 10 fewer maternal deaths, 650 additional uterine ruptures, and 50 additional neonatal deaths. Additionally, it is important to consider the morbidity in future pregnancies that would be averted from multiple cesareans particularly in association with placental abnormalities.