Applying medical research to clinical 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?
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:
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
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Jen Kamel is the founder of VBAC Facts, an educational, training and consulting firm. As a nationally recognized VBAC strategist and consumer advocate, she has been invited to present Grand Rounds at a hospital, served as an expert witness in a legal proceeding, and has traveled the country educating hundreds of professionals and highly motivated parents. Even more have accessed her trainings online. She speaks at national conferences and has worked as a legislative consultant in various states focusing on midwifery legislation and regulations. She has testified multiple times in front of the California Medical Board and legislative committees on the importance of VBAC access and is the Secretary for the California Association of Midwives and the California Association of Licensed Midwives. Her favorite flavor of ice cream is peanut butter chocolate. And mint chip. And coffee.