Tag Archives: understanding medical studies

Applying medical research to clincial realities

Isabel recently asked over on Uterine rupture rates after 40 weeks:

“I wonder however if there are studies that compare the method of induction. My Doula said that the increase rates of uterine/ scar rupture was due to using high dosages of Pitocin, but now the induction uses lower dosages and administered at longer intervals. Do you know something about this?
Thank you”



Great question.

A few factors to consider:

1. Induction protocols can vary by provider, including some providers who don’t induced planned VBACs at all.
2. Induction guidelines can vary by hospital.
3. Women can react to the same drug/dose differently.
4. Some studies do compare the uterine rupture rates among spontaneous, induced, and augmented planned VBACs.

Medical studies on induction are only relevant to your situation if your provider follows the same protocol outlined in the study. However induction protocols are often not spelled out in detail unless that is the focus of the study.

When reading medical research, make special note of the sample size. We need ample participants in order to accurately capture and report the incidence of uncommon events such as uterine rupture. I typically like to see at least 3,000.  

Also remember that it’s ideal to have a experimental group (who receives the induction protocol) and a control group (who does not receive the induction protocol) in order to measure the difference in outcomes, such as fetal distress, uterine rupture, hemorrhage, cesarean hysterectomy, etc. Ideally, we would have a couple thousand, at least, in the experimental and control group.

In terms of the trend that induction now uses lower dosages and is administered at longer intervals, that may be true in some practices, but I would always confirm and not assume.

Anecdotally, I have heard a wide range of induction protocols reported just as research has identified similar variations among cesarean and episiotomy rates that are not linked to medical indication. This California Healthcare Foundation infographic clearly illustrates how hospitals differ:

Tale of Two Births

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In terms of specific studies comparing the method of induction, the first resource that comes to mind is the Guise 2010 Evidence Report.

Search for the word Cytotec and there is a discussion comparing rates of rupture by Pitocin, prostaglandins, and Cytotec.

Pitocin is associated with the lowest rate of rupture among the chemical agents which is likely why ACOG (2010) recommends Pitocin and/or Foley catheter induction in planned VBACs when a medical indication presents. (Learn more about what the Pitocin insert actually says.)

There may be more recent studies out there. Google Scholar is a good place to start. You can often obtain the full texts of medical studies at your local library, university, or graduate school.

Also, if you subscribe to Evidence Based Birth’s newsletter, she will email you a crash course on how to find good evidence.

I hope this helps!


What is the induction protocol at your facility? Does it differ for those with a prior cesarean? Let me know in the comment section.


American College of Obstetricians and Gynecologists. (2010). Practice Bulletin No. 115: Vaginal Birth After Previous Cesarean Delivery. Obstetrics and Gynecology, 116 (2), 450-463, http://dhmh.maryland.gov/midwives/Documents/ACOG%20VBAC.pdf

California Healthcare Foundation. (2014, Nov). A Tale of Two Births: High- and Low-Performing Hospitals on Maternity Measures in California. Retrieved from California Healthcare Foundation: http://www.chcf.org/publications/2014/11/tale-two-births

Guise, J.-M., Eden, K., Emeis, C., Denman, M., Marshall, N., Fu, R., . . . McDonagh, M. (2010). Vaginal Birth After Cesarean: New Insights. Rockville (MD): Agency for Healthcare Research and Quality (US). Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK44571/

Friedman, A. M., Ananth, C. V., Prendergast, E., Alton, M. E., & Wright, J. D. (2015). Variation in and factors associated with use of episiotomy. JAMA, 313(2), 197-199. Retrieved from http://jama.jamanetwork.com/article.aspx?articleid=2089343

Kozhimannil, K. B., Arcaya, M. C., & Subramanian, S. V. (2014). Maternal Clinical Diagnoses and Hospital Variation in the Risk of Cesarean Delivery: Analyses of a National US Hospital Discharge Database. PLoS Med, 11(10). Retrieved from http://journals.plos.org/plosmedicine/article?id=10.1371%2Fjournal.pmed.1001745

Does the term “TOLAC” tweak you?

On the acronym TOLAC (trial of labor after cesarean)….

Some studies break out statistics in four ways.

1. ERCS/D (elective repeat cesarean section/ delivery)
2. VBAC (vaginal birth after cesarean)
3. CBAC (cesarean birth after cesarean aka cesarean after planned VBAC)
4. TOLAC (VBAC + CBAC stats)

Because we are unable to predict who will have a VBAC or CBAC, the TOLAC stat enables us to review outcomes from a variety of angles:

  • TOLAC vs. ERCS
  • VBAC vs. ERCS
  • CBAC vs. ERCS

Some women find the TOLAC acronym offensive, because it implies “trying,” so practitioners sensitive to this may way to use the phrase “planning a VBAC.”   Understanding that TOLAC isn’t a dig at moms, but just a straightforward, objective term that care providers use, can (hopefully) take the sting out of the word.

Remember, your care provider is not your girlfriend.  They use clinical terms because that is the language of their world. They speak like clinicians because they are clinicians. All that said, providers who are aware of how the term TOLAC is received by some women use the term “planned VBAC.”

So moms, you use the language that works for you! Just remember that TOLAC is really more of a clinical term and when your provider uses it, it doesn’t necessarily mean that they are a jerk.  They just may have forgotten to code switch from clinical to sensitive language.

Moms don’t typically say, “I’m so excited for my TOLAC!” However, if you do, you might make your provider laugh and connect with them on a human level.

Two points for the person who knows how this picture is relevant…