Vaginal Birth After Cesarean Delivery
- Most women with a prior cesarean delivery with a low transverse incision are candidates for VBAC and should be offered TOLAC;
- Epidural anesthesia may be used as part of TOLAC;
- Misoprostol should not be used for patients who have had a prior cesarean delivery or major uterine surgery.
- Two previous low transverse cesarean deliveries;
- One previous cesarean delivery with a low transverse incision, who are otherwise appropriate candidates for twin vaginal delivery;
- One previous cesarean delivery of unknown incision type, unless clinical suspicion of a previous classical uterine incision is high.
- Induction of labor during TOLAC is not contraindicated;
- In women with a prior low transverse uterine incision who are at low risk for adverse maternal or neonatal outcomes from external cephalic version and TOLAC, external cephalic version for breech presentation is not contraindicated.
Finally, 2 large multicenter studies have been publishing multiple studies on this issue, one out of Pennsylvania and the other out of the Maternal-Fetal Medicine Units. These large studies over the last decade have used multivariate statistics to examine risk factors. This means that other risk factors and confounding factors, such as birth weight, maternal age, obstetric history, and labor management, were controlled for in the analysis. In this article, factors associated with mode of delivery in the setting of a trial of labor and factors associated with uterine rupture in this same setting are reviewed.
Predictors of a Successful Trial of Labor
|Increased Chance of Success||Decreased Chance of Success|
|Prior vaginal delivery||Maternal obesity|
|Prior VBAC||Short maternal stature|
|Favorable cervix||Increased maternal age (>40)|
|Nonrecurring indication (breech, previa, herpes)||Induction of labor|
|Preterm delivery||Recurring indication (cephalopelvic disproportion [CPD], failed second stage)|
|Increased interpregnancy weight gain|
|Latina or African-American race/ethnicity|
|Gestational age ≥ 41 weeks|
|Preconceptional or gestational diabetes mellitus|
Risk Factors for Uterine Rupture
Table 2: Predictors of Uterine Rupture
|Increased Rate of Uterine Rupture||Decreased Rate of Uterine Rupture|
|Classical hysterotomy||Spontaneous labor|
|Two or more cesarean deliveries||Prior vaginal delivery|
|Single-layer closure||Longer interpregnancy interval|
|Induction of labor||Preterm delivery|
|Use of prostaglandins|
|Short interpregnancy interval|
|Infection at prior cesarean delivery|
|Study||Sample Size (N)||Rates|
|Miller, 1994||10,880||63 uterine ruptures (0.6%)*|
|Flamm, 1994||5,022||39 uterine ruptures (0.8%)|
|McMahon, 1996||3,249||10 uterine ruptures (0.3%)|
|Shipp, 1999||2,912||28 uterine ruptures (1%)|
|Landon, 2004||17,898||124 uterine ruptures (0.7 %)|
|Macones, 2005||13,331||128 uterine ruptures (0.9%)|
Several studies examining this issue have demonstrated that the rate of rupture for patients with an unknown uterine incision is approximately 0.6%. A case-control study of patients with and without uterine rupture did not find unknown hysterotomy to be a risk factor compared with low transverse hysterotomy.6
The rate of asymptomatic uterine dehiscence in patients undergoing a trial of labor after cesarean delivery is difficult to assess because it is not commonly investigated. Thus, while the overall power examining this issue in twins is not overwhelming, certainly no evidence suggests a higher risk of uterine rupture in these women.
However, among the 15,801 women who elected to have a repeat cesarean delivery, 2 maternal deaths were reported. Among the 17,898 women who underwent a trial of labor, no maternal deaths were reported due to the trial of labor or uterine rupture. This difference was too small to be statistically significant; however, the risk of repeat cesarean delivery to maternal morbidity and mortality should be considered.9
More recently, a study demonstrated that of 15,338 patients at term undergoing a trial of labor, 2 neonatal deaths and 7 cases of hypoxic-ischemic encephalopathy occurred for rates of 1.4 per 10,000 and 4.6 per 10,000 trials of labor, respectively.9 In their series, 114 uterine ruptures occurred among these patients, giving rates of 1.8% of neonatal death per uterine rupture and 6.2% of hypoxic-ischemic encephalopathy per uterine rupture.
Further, with each subsequent cesarean delivery, the risks of maternal morbidity and, potentially, maternal mortality increase. Thus, for a woman who wants more children, taking the risk of a trial of labor in the current pregnancy may hold more long-term benefits than the woman who is planning on a tubal ligation after delivery.
Management of Patients With Prior Cesarean Deliveries
- Acute abdominal pain, persistent beyond contractions
- A popping sensation
- Palpation of fetal parts outside the uterus upon Leopold maneuvers
- Repetitive or prolonged fetal heart rate deceleration
- High presenting part upon vaginal examination
- Vaginal bleeding