Myth: Risk of uterine rupture doesn’t change much after a cesarean
I have come across a couple different bits of (mis)information that have really concerned me. In both situations, people give false information regarding how a cesarean affects one’s risk of uterine rupture in future pregnancies. First, a women asks on Facebook: “What is the risk of rupture is after a cesarean.” She receives this reply:
… almost all cases the risk of rupture is less than one percent, even after multiple sections, or special scars such as an inverted T. The risk is roughly double what it is for an unscarred uterus, but considering the tiny numbers it doesn’t really make a difference, especially since the vast majority of ruptures are not catastrophic in nature, something that is not differentiated in study results.
Then later in the day, I came across a comment on a midwife’s website saying that “research shows” the risk of uterine rupture doubles after a cesarean.
The risk of uterine rupture after a cesarean
Both of these representations of uterine rupture after a cesarean are incorrect. The risk of a uterine rupture does much more than double after a cesarean.
This is because the risk of uterine rupture in an unscarred uterus is very small in comparison to the risk in a scarred uterus. Prior to having a uterine surgery like a cesarean, the risk of uterine rupture is incredibly remote. Per the largest study on unscarred rupture, the risk is 1 in 14,286 or 0.007%. (Zwart, 2009)
Once someone has a cesarean, that risk increases to 1 in 156 or 0.64%. (Zwart, 2009)
This study found that the risk of uterine rupture increases 91 times after a cesarean.
But this is also true: this 91 times greater risk does not mean that the risk of uterine rupture is excessive or unreasonable after a cesarean. It simply means that it’s so rare in the absence of prior uterine surgery.
Plus, that 1 in 156 rate includes labors that were induced and augmented which we know increases the rate of rupture. When we look at studies that break out the risk of rupture among spontaneous labors, the risk decreases to 1 in 240 or 0.4%. (Landon, 2004)
Relative versus absolute risk of uterine rupture
So how we communicate these statistics impacts how they will be received.
Do we center how the risks compare – the relative risk – and talk about the 91 times increase?
Or do we focus on how often uterine rupture occurs – the absolute risk – and emphasize the 0.64% risk?
I believe that information is power and the more information parents have, the greater their ability to make informed decisions that feel right for them. So it’s important to talk about both.
Parents should understand how their cesarean impacts their future uterine rupture risk as well as how another cesarean can impact their future fertility, pregnancies, and deliveries. And they also need to understand that this increased risk is still similar to other obstetrical emergencies even first time parents can experience.
How to make an informed decision about VBAC
The risk of uterine rupture is just one of the many factors that parents should learn about and consider in order to make an informed decision on whether they want to plan a VBAC or repeat cesarean.
This is why the American College of OB/GYNs describes VBAC as a safe and reasonable option and encourages parents to have access to it.
The truth is, both modes of delivery have uncommon, though very serious, risks associated with them. Parents can only decide which set of risks and benefits are acceptable to them if they actually know the facts. Knowing solely about the risk of rupture does not give them a full picture.
Zwart, J. J., Richters, J. M., Ory, F., de Vries, J., Bloemenkamp, K., & van Roosmalen, J. (2009, July). Uterine rupture in the Netherlands: a nationwide population-based cohort study. BJOG: An International Journal of Obstetrics and Gynaecology, 116(8), pp. 1069-1080.
What do you think?
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As an internationally recognized consumer advocate and Founder of VBAC Facts®, Jen helps perinatal professionals, and cesarean parents, achieve clarity on vaginal birth after cesarean (VBAC) through her educational courses for parents, online membership for professionals, continuing education trainings, and consulting services. She speaks at conferences across the US, presents Grand Rounds at hospitals, advises on midwifery laws and rules that limit VBAC access, educates legislators and policy makers, and serves as an expert witness and consultant in legal proceedings. She envisions a time when every pregnant person seeking VBAC has access to unbiased information, respectful providers, and community support, so they can plan the birth of their choosing in the setting they desire.