I just read a blog where a woman, with a prior vaginal birth and two cesareans, was told that her risk of uterine rupture was 5%. She was also told that since her VBAC would be within one year of her cesarean, her rupture risk doubled to 10%. It just breaks my heart to read of women receiving such misinformation from their OBs.
So, here is the link to Risk of Uterine Rupture With a Trial of Labor in Women With Multiple and Single Prior Cesarean Delivery (Obstetrics & Gynecology 2006;108:12-20) by Landon, et al, which I will refer to as Landon 2006.
This study of 975 women with multiple prior cesareans found a rupture rate of 0.9%. That’s a lot smaller than 5%. When will OBs either stop lying to women or get their facts straight?
Landon 2006 does not look at VBA2C within a year, but it does look at within two years. They found women whose VBA2C was two years or less after their cesarean to have a rupture rate of 1.1%. That’s a 1.2 times greater risk. Not double.
And women with a prior vaginal delivery, like our woman in question, had a rupture rate of 0.5%. Yes, half a percent. (Here’s the chart where you can see the 1.1% and 0.5% statistic.)
Landon 2006 lists other studies looking at rupture rates of VBA2C and found none reporting rates as high as 5%:
Landon 2006 concludes (emphasis mine):
A history of multiple cesarean deliveries is not associated with an increased rate of uterine rupture in women attempting vaginal birth compared with those with a single prior operation. Maternal morbidity is increased with trial of labor after multiple cesarean deliveries, compared with elective repeat cesarean delivery, but the absolute risk for complications is small. Vaginal birth after multiple cesarean deliveries should remain an option for eligible women.
In terms of success rates:
The overall trial-of-labor success rate was 13,138 of 17,890 (73%). Women with a single prior cesarean delivery had a success rate of 12,490 of 16,915 (74%) compared with 648 of 975 (66%) in women with multiple prior cesarean deliveries (P < .001). The trial of labor success rates were 584 of 871 (67%) for two prior, 53 of 84 (63%) for three prior, and 11 of 20 (55%) for four prior cesarean deliveries (P < .001).
In terms of infant (perinatal) outcomes:
Although our study also provides perinatal outcome data demonstrating no apparent increased risk with trial of labor compared with elective repeat cesarean delivery after multiple prior cesareans, we recognize that the population size is insufficient to address differences in these outcomes. It is, however, likely that a larger study population would demonstrate a small but increased risk for adverse perinatal outcomes in women undergoing trial of labor as we have demonstrated in the combined cohort of women with single and multiple prior operations.
But I wanted to look into this “within one year” issue and found Getting Pregnant After a Cesarean on BabyCenter which states:
In one study of 170 women, the risk of scar rupture was significantly higher when the gap between pregnancies was less than six months. In another more powerful, study of 2,409 women who opted for a VBAC, the women who had conceived within 18 months of their previous section were three times more likely to have a scar rupture than women with a longer gap between pregnancies. In a third study an increased risk of scar rupture was seen for women who had had a premature delivery by caesarean section, particularly if they hadn’t laboured at all before the section and if the gap between the deliveries was less than two years.
After a little research, I found the study of 2,409 women which I will refer to as Shipp 2001. Entitled Interdelivery Interval and Risk of Symptomatic Uterine Rupture (Obstetrics & Gynecology 2001;97:175-177), it looked at women with one prior cesarean and no prior vaginal births. They found rupture rates of 2.25% up to 18 months after cesarean and 1.05% for 19 months or longer. They concluded: “Women with interdelivery intervals of up to 18 months were three times as likely (95% confidence interval, 1.2, 7.2) to have symptomatic uterine rupture.”
So, Shipp 2001 shows a 2.25% UR risk in women with one prior CS and no prior vaginal births.
Landon 2006 shows a 0.9% UR risk in women with two prior CS and a 1.1% UR risk (a 1.2x greater risk) when VBA2C is within two years of the prior CS.
However, neither Shipp 2001 or Landon 2006 breaks out the numbers for women, like the one from the blog, with one prior vaginal birth AND two cesareans with a VBA2C within one year of her last CS. But I think by looking at the information from both studies, we can extrapolate that it’s way lower than 10% she was quoted.