Cervical Dilation: 50% of the Time, It’s 100% Right.
And that is a problem.
You are ready for this baby to arrive. You set up the crib. You installed the car seat. You packed the hospital bag. You read all the books. You attended all the classes. You wait in anticipation for any sign of labor.
And… finally! You feel a painful contraction. This must be it. You start timing contractions. When your contraction-timing fulfills the magic “5–1–1 rule” (contractions that last 1 minute, 5 minutes apart, for 1 hour), you grab that carefully packed hospital bag and rush to Labor and Delivery.
Upon arriving, the nurse cheerfully tells you, “We need to do a cervical exam to know if you’re in active labor before we can admit you.”
One more hurdle to jump through? During labor?!
The Cervical Dilation Exam
Ok, so what is the nurse talking about?
First, a quick refresher: The cervix is the doorway to the uterus, and has been keeping the baby safely cooking for the last, approximately, 40 weeks. During labor, the cervix goes from closed (0 centimeters dilated) to fully dilated (10 centimeters dilated). Yes, it’s a huge change. Medical providers rely on dilation measurements to gauge “labor progress,” along with measurements of your contractions and your reports about how you feel.
So what, exactly, is the nurse doing when she conducts your cervical exam? Medical providers gauge cervical dilation by feeling the cervical opening with two fingers. They place their two fingers on either side of the cervical opening and estimate how far apart their fingers feel. They can’t see the cervix during the exam since the cervix is located at the back of the vagina. Providers must blindly estimate how far apart their fingers feel.
Unfortunately, there is currently no better way or tool to measure cervical dilation.
Why Accuracy Matters When it Comes to Cervical Dilation
As you might have guessed, measuring cervical dilation is an imprecise science.
In one study, when two experienced OB/GYNs examined the same woman’s cervix, they agreed on dilation only 49% of the time. Several other clinical trials using cervical simulators also found that clinicians correctly estimated the dilation only half the time, regardless of years of practice or type of education.
“The assessment of the cervix is the cornerstone of the management of labour.” (Tufnell et al. 1989)
Clinicians actually have very few tools in their labor assessment kits: Digital exams (dating back to 1900 BCE) and a tocometer to measure contractions (dating back to 1971.)
Knowing that this examination decides your admission fate is nerve-wracking enough when you are in labor. But, accuracy becomes even more important once you have made it through admission. During labor, your provider measures dilation over time and recommends interventions. These recommendations may include pitocin or breaking the bag of water if the dilation does not change.
If dilation continues unchanged for over four hours during active labor, with strong contractions, the American College of Obstetricians and Gynecologists recommends that doctors perform a cesarean delivery. In the United States, 13% of cesarean deliveries (over 165,000 births) are performed each year because the dilation stopped changing. The number of cesarean sections performed for this specific reason — “arrest of dilation” — has only seen increases in recent years, contributing to the overall high rate of cesarean deliveries in the U.S.
“The rapid increase in cesarean birth rates … raises significant concern that cesarean delivery is overused.” (ACOG)
Where do we go from here?
For your own pregnancy and birth, you can prepare yourself as best you can for whatever comes down the pike. Educate yourself about the strengths and weaknesses of the various tools clinicians use to assess labor. Maintain a healthy skepticism. Be your own advocate and empower those around you with information to advocate on your behalf. Ask your provider lots and lots of questions.
For the future of pregnancy, join the movement to change the future of prenatal care. Support research and development in obstetrics. Support innovation and the companies working hard to build and improve tools for understanding labor and empowering clinicians and patients with the most accurate information to make better decisions.
Women deserve more innovation.
Share your story!
Did cervical dilation play a role in your labor? Did your providers’ measurements always agree? Did the disagreement impact your decision-making?
Dr. Eva Martin is the CEO and Founder of Elm Tree Medical, Inc., a medical device company devoted to innovating in the field of women’s health. They are currently developing a device to increase the accuracy of cervical dilation measurements. To learn more, please visit their website dilacheck.com or connect with her on Twitter @elmtreemedical or Facebook. If you’d like to share your story of how cervical dilation impacted you, comment below or email Eva at evamartin@elmtreemedical.com.
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