Who is a good candidate for VBAC?
August 9, 2016
“Once a C-section, always a C-section.”
This is what doctors used to tell women who had a cesarean section. But it’s not true for everyone.
Vaginal birth after cesarean section (VBAC) often is an option. In fact, studies have shown a 60 to 80 percent success rate for women who attempt VBAC.
The American Congress of Obstetricians and Gynecologists has recommended VBAC as a safe and appropriate choice for most women who have had a prior C-section. However, not all doctors or hospitals are equipped to handle a VBAC, and some simply choose not to do them.
I think VBAC is wonderful option for many women. But it’s a personal decision that should be made after carefully weighing the risks and benefits and your plans to have more children.
What are the risks and benefits of VBAC?
For most women, C-section carries greater risk than a vaginal delivery. But a repeat C-section significantly increases the risk of complications such as of infection, injury to adjacent organs, abnormal implantation of the placenta, and placenta previa, in which the placenta completely or partially covers the cervix.
Because C-sections become more risky with every subsequent surgery, you may want to consider VBAC, especially if you plan to have a large family.
Uterine rupture is the main risk cited for VBACs. This is a tear in the wall of the uterus, and it often occurs at the site of a previous C-section incision. While uterine rupture is a potentially dangerous complication, it’s rare. Most studies show that for women who have had one prior C-section with a low-transverse (horizontal) incision, the risk of uterine rupture is less than 1 percent.
Why is the risk of uterine rupture important to consider? First, uterine risk carries the potential for serious consequences to the mother – including blood transfusions and hysterectomy to control the bleeding. There is also a risk of serious injury or even death to the baby caused by decreased blood flow to the baby.
Obviously, VBAC is an optimal delivery outcome. But a failed VBAC that results in an emergency C-section also is risky. It’s important when considering VBAC to talk with your doctor about your risks and likelihood of a successful VBAC.
Am I a good candidate for VBAC?
We can’t promise anyone a successful VBAC, but some factors may improve your chances:
- If you’ve had a previous vaginal delivery: This includes if you’ve already had a successful VBAC.
- Age: A 2007 study found that women younger than 35 were more successful and had fewer complications during a VBAC.
- Incision: A low-transverse (horizontal) uterine incision is the optimal incision for VBAC.
- Reason for first C-section: Your chance of VBAC success increases if your C-section was for what we call a non-repetitive indication. This means the C-section was performed for the baby’s health, not because of the actual labor process. Examples include a breech baby or abnormal fetal heart rate tracing.
There are many online calculators that predict your chance of a successful VBAC. I like the calculator on the Maternal-Fetal Medicine Unit’s network. It takes into account factors such as age, weight, and previous deliveries.
Obviously, these calculators are not 100 percent accurate, but they can help with your decision about attempting VBAC. If your chance of a successful VBAC is 70 percent, you must decide whether that’s a good enough number for you or whether you’d prefer to schedule a repeat C-section.
When do we not recommend VBAC?
There are few instances in which I would say no to a VBAC. Other times I may tell you that your chances aren’t great, but we can try. In those cases, we’ll have a conversation about the risks and at what point during labor we would go for a C-section.
- Incision: I — and most physicians I know — will not attempt a VBAC if your previous C-section resulted in a vertical incision (known as a “classical” incision) or a T-shaped incision. These put you at higher risk for uterine rupture.
- Labor dystocia: This refers to an abnormally slow or difficult labor. If your previous C-section was because of this, it doesn’t exclude you from trying VBAC, but we’ll talk about how long we want to attempt vaginal labor.
- Multiple C-sections: Your chance of a successful VBAC goes down with multiple C-sections. Not every physician will feel comfortable working with you to try VBAC after a second C-section. Nearly no physician will try it after three or four C-sections.
- Health complications: An emergency C-section can be especially dangerous if you have a condition such as lung disease or a heart defect. In these cases, we will even more carefully weigh the risks and benefits of VBAC.
- Having a large baby: We still can’t pinpoint fetal weight in the third trimester, but if we suspect your baby is over 10 pounds, we may suggest rethinking a VBAC.
- Going past your due date: If you go beyond 40 weeks of pregnancy, the odds of induction and having a large baby increase. Many doctors are reluctant to induce labor in a patient with any type of prior uterine surgery because of concerns for an increased risk of uterine rupture.
How can I increase my chances for a successful VBAC?
Many factors that contribute to a successful VBAC are out of your hands, but there are things you can do to increase your chances:
- Talk with your doctor about VBAC early in the pregnancy: Ask if your doctor and hospital will support you in a VBAC attempt. The availability of anesthesiologists plays an important role in the safety of trying to have a VBAC. You don’t want to find out a week before your due date that they aren’t comfortable handling VBACs.
- Manage your weight: A2013 study showed that overweight women who lost at least 1 body mass index unit increased their chance for a successful VBAC by 12 percent (compared to overweight women who maintained their weight). Talk with your doctor about how to lose weight before you become pregnant, manage your diet, and become active or stay active during pregnancy.
- Let Mother Nature run her course: Your chance for a successful VBAC increases if you go into labor on your own. The risk of uterine rupture slightly rises if you are induced. The average risk of uterine rupture is 0.7 percent. That goes up to 0.9 to 1 percent if you are induced with Pitocin and 1.4 to 1.8 percent with prostaglandin.
Why don’t all doctors and hospitals allow VBACs?
It was common practice in the 1960s and 1970s to perform a repeat C-section after a prior cesarean birth. But as the C-section rates began to soar, doctors started to rethink how we approach these situations.
VBACs were on the rise while I was in medical school and residency in the 1990s. Unfortunately, some ill-advised VBAC attempts caused the number of uterine ruptures and other complications to increase – along with the number of lawsuits. Because of this, we saw VBACs decline in the 2000s while C-section rates increased to today’s rate of nearly 30 percent.
Some doctors and hospitals are not equipped to handle an emergency C-section, and therefore don’t feel comfortable allowing a woman to attempt a VBAC. Some are hesitant to offer them because of the potential for lawsuits. Others are just more conservative in their labor and delivery practice.
If your doctor or hospital does not allow VBAC, and you’re passionate about trying it, ask them to refer you to one that does. You’ll often find large, university-based hospitals or community hospitals with 24/7 labor and delivery and anesthesia teams promote this method of delivery.
Ultimately, we want you and your baby to be healthy. We don’t want you to be cavalier about this decision. There has to be an honest assessment of your risks and of how labor is progressing. I tell patients that as long as they are following the normal labor curve, we keep going. However, if things begin to mimic what happened in their previous pregnancy, we may need to stop before an emergency C-section becomes necessary.
If you’ve had a C-section but hope to experience a vaginal delivery with your next child, consult with your doctor about their views on VBAC and whether you may be a good candidate to try it. And if you aren’t a good candidate, explore how your hospital accommodates families during C-sections – you may be pleasantly surprised how different your experience this time may be.
If you would like to talk with one of our physicians about VBAC, request an appointment online or call 214-645-8300.