Hi Henci,

Im sure you've read AAFPs new stance on VBAC
http://www.annfammed.org/cgi/data/3/4/378/DC1/1
Several times they mention "Maternal death rates do not differ between TOLAC and ERCD"
I just can not fathom this. How can major surgery not have a higher death rate?

Christa Bartley
www.birthNETWORK.org By: RNChrista

The likelihood of a healthy woman dying during a relatively simple surgery in this day and age is miniscule. This means that the rate of maternal death during elective repeat cesarean surgery vs. planned vaginal birth is so low that it would take a huge sample size to show a difference. The sample size here was 19,000 women--not big enough.

Of interest, though, is that the AAFP practice guidelines, which are based on an Agency for Healthcare Research and Quality (AHRQ) systematic review, the highest quality source of evidence we have on the issue, also state that there is no difference in hysterectomy and contradictory evidence on transfusion rates. Again, if you compare rates between planned vaginal and planned cesarean birth overall, these complications are too rare for differences to show up in a statistical analysis. However, it you look at rates with multiple prior cesareans vs. one prior cesarean, or VBAC, differences are significant. This is because rates of both those outcomes climb as the number of cesareans goes up, which in turn happens because rates of placenta previa (placenta overlays the cervix) and placenta accreta (placenta invades the muscular wall of the uterus, sometimes growing through it and invading pelvic organs) also climb as the number of cesareans goes up. If you look at the bigger picture: that a woman may go on to have more children either planned or unplanned, the balance tips toward planned VBAC. With supportive care, her chances of VBAC are 75% (3 out of 4). Even when factors are against vaginal birth, her likelihood in the worst case is still 50/50. (I find it fascinating, by the way, that not one study looking at factors influencing likelihood of VBAC look at care provider practice variation or attitude, which, of course, is the biggest influence of all.) A vaginal birth ends her exposure to the potential harms of accumulating cesarean sections.

The AAFP guidelines state that the AHRQ systematic review also fails to find an association between inducing labor by whatever method or strengthening labor with oxytocin. This puzzles me. I happen to be in the middle of studying this issue, and I'm finding a consistent association with the scar giving way in the studies I'm reading. I'm going to get the AHRQ report and take a look.

-- Henci By: Henci Goer

Thanks for replying Henci.
While it was great to see they had some positive information, some things puzzled me too, including the lack of association of labor induction/augmentation with uterine rupture. Keep us informed on what the AHRQ report says.
Thanks! By: RNChrista

"Thanks for replying Henci.
While it was great to see they had some positive information, some things puzzled me too, including the lack of association of labor induction/augmentation with uterine rupture. Keep us informed on what the AHRQ report says.
Thanks!"

Sorry it took a while to get back to you. Here's the scoop on the AHRQ systematic review:

Starting with all induction vs. spontaneous labor, 8 studies made their cut totalling 1,671 women being induced with PGE2, oxytocin, or amniotomy/oxytocin/PGE2 and one tiny study of 16 women induced with mifepristone vs. 16 spontaneous labors. I doubt that this small a population sample has the statistical power to detect a small, but clinically important, difference between groups. Also, all the induction studies the AHRQ reviewers cited antedate the rise in the use of single-layer uterine suturing.

Similarly, only four studies of oxytocin induction vs. spontaneous labor were included, the latest of which was published in 1990. The total # of women induced with oxytocin was 2108. Here again, this means the population is too small to be likely to detect a difference. In addition, The likelihood of rupture depends on oxytocin protocol. I'd be willing to bet obstetricians were much more cautious about oxytocin back in the 1980s than they are now.

As for PGE2 induction, they cited three studies totalling 625 women having PGE2 induction. Same problem here.

Recent studies published since the AHRQ group ran their lit searches show a consistent increase in scar rupture rates with oxytocin and PGE2 use. The one exception is one out of Italy that designed a strict protocol for induction and augmentation different from the one they use on women with no uterine scar and that takes into account the vulnerability of the scar. (Locatelli A, Regalia AL, Ghidini A, et al. Risks of induction of labour in women with a uterine scar from previous low transverse caesarean section. BJOG 2004;111(12):1394-9.) They had a scar rupture rate of 0.3%--that's 3 per 1,000--in induced and spontaneous onset labors and a VBAC rate of 71% in induced labors and 82% in spontaneous onset labors.

Late next winter (Feb 2006), the Coalition for Maternity Services will be publishing a document tentatively entitled "Evidence Basis for the Ten Steps to Mother-Friendly Care." This will put a lot of the data grassroots groups and progressive care providers need for issues such as the one raised here at their fingertips.

-- Henci
By: Henci Goer