Increasing the Odds for Success With VBAC
If your institution allows higher levels, be extra vigilant as the dosage increases.
▸ Be leery of intrauterine pressure catheters. Old data had suggested that intrauterine pressure catheters could be useful for predicting uterine rupture during trials of labor after cesarean. However, these data have not been supported by further research. I do not recommend the routine use of these catheters to try to predict uterine rupture in women attempting VBAC.
▸ Be aware of signs of possible rupture. Clinical suspicion should be high in women who have unusual pain when epidural anesthesia is already in place and in women who need frequent epidural dosing during a VBAC trial.
Research has shown that both conditions are markers for possible impending uterine rupture during VBAC attempts. An analysis of 504 women who had epidural anesthetic during attempted VBAC, for instance, showed that women who had a uterine rupture received more epidural doses on average, especially during the final 90 minutes of labor, than women who did not have a uterine rupture (Am. J. Obstet. Gynecol. 2010;202:355.e1-5).
▸ Keep patients informed. Keeping your patient informed and comfortable with her options for delivery after cesarean section involves counseling throughout the course of prenatal care and could even include the use of an actual informed consent form for a trial of labor, which can help facilitate thorough discussions about the risks and benefits of attempting VBAC. Informed consent should extend into labor, however. Patients can be told that it is acceptable to inquire about stopping a trial of labor at any point. Giving patients the opportunity to “opt out” can be a good thing; it gives them more control over what's happening.
Consequences of Not Doing VBACs
There is a danger to too easily dismissing VBAC. Although most research has focused on uterine rupture and the index pregnancy, there is also research that clearly shows that serious maternal morbidity increases progressively with each repeat cesarean delivery. With multiple cesareans, each delivery becomes more complicated and carries more risk. The effect on maternal health can be profound.
A prospective observational study of approximately 30,000 women who had cesarean delivery without labor showed that the risks of cystotomy, bowel injury, ureteral injury, hysterectomy, and the need for postoperative ventilation, intensive care unit admission, and significant blood transfusion all were significantly increased with increasing numbers of cesarean deliveries (Obstet. Gynecol. 2006;107:1226-32).
Even more concerning is the risk of abnormal placentation. In this study, placenta accreta occurred in 0.24%, 0.31%, 0.57%, 2.13%, 2.33%, and 6.74% of women who were undergoing their first, second, third, fourth, fifth, and sixth or more cesarean deliveries. In women with placenta previa, the risk for placenta accreta rose progressively with each cesarean delivery—3.3% with the first cesarean, 11% with the second, 40% with the third, 61% with the fifth, and up to 67% with the fifth and sixth cesareans.
Because the rates of abnormal placentation are rising in the United States, it is extremely important that we consider not only the short-term complications of VBAC, such as uterine rupture, but also the long-term consequences of multiple repeat cesarean deliveries.
This part of the overall safety profile of VBAC is discussed in the NIH's draft consensus conference statement. The statement points out that women who have had VBAC have reduced abnormalities of placental growth and position in subsequent pregnancies, and that the incidence of placenta previa significantly increases in women with each additional cesarean delivery.
In counseling about elective repeat cesarean delivery versus a trial of labor, I often talk with women about the number of children they intend to have. If a woman has had a prior cesarean delivery and desires a large family, I am very inclined to strongly encourage her to pursue a trial of labor.
Vitals
Source Elsevier Global Medical News
Key Points
Dr. Macones offered these take-home points:
▸ Rates of uterine rupture and hypoxic ischemic encephalopathy are higher in women who attempt VBAC, but the absolute rates are quite low and similar to the complication rates of most other obstetrical procedures we do.
▸ Prior vaginal delivery is the only clinically useful predictive factor for VBAC success.
▸ VBAC outcomes can be maximized by inducing labor only when necessary, avoiding the use of multiple induction agents, avoiding higher doses of oxytocin, and being aware of signs of possible rupture.
▸ The long-term impact of multiple repeat cesareans should be factored into decision making, as serious maternal morbidity increases with each repeat cesarean delivery.
