Do vaginal birth after cesarean outcomes differ based on hospital setting?

OBJECTIVE: The objective of the study was to test the null hypothesis that outcomes of vaginal birth after cesarean (VBAC) do not differ on the basis of the hospital setting. STUDY DESIGN: The study was a retrospective cohort study of women who were offered VBAC in 17 hospitals from 1996 to 2000. VBAC attempts occurring in hospitals with and without obstetrics-gynecology residency programs were compared, as were outcomes from university and community hospitals. Bivariate and multivariate logistic regression analyses assessed the association between hospital setting and VBAC outcomes. RESULTS: Of 25,065 women with 1 or more prior cesareans, the VBAC attempt rate was 56.1% at hospitals with obstetrics-gynecology residencies, 51.3% at hospitals without obstetrics-gynecology residencies, 61% at university hospitals, and 50.4% at community hospitals. The occurrence of failed VBAC, blood transfusion, or composite adverse outcome did not differ by hospital setting. There was a significant increase in the uterine rupture rate at community (1.2%) vs university hospitals (0.6%), but the absolute risk remained low. CONCLUSION: The rate of VBAC-associated complications is low, independent of hospital setting.

Does a maximum dose of oxytocin affect risk for uterine rupture in candidates for vaginal birth after cesarean delivery?

OBJECTIVE: The purpose of this study was to determine whether the maximum dose of oxytocin impacts the risk of uterine rupture in women who attempt vaginal birth after cesarean delivery (VBAC). STUDY DESIGN: We conducted a retrospective, multicenter cohort study of women with a history of cesarean delivery. We compared uterine rupture rates between VBAC candidates that did and did not receive oxytocin, analyzing the association between maximum dose of oxytocin and uterine rupture. Bivariate and multivariate analyses were performed. RESULTS: Of the 13,523 patients who elected a VBAC trial, 128 women experienced a uterine rupture; 80 of these ruptures were in women who received oxytocin (62.5%). There was evidence of "dose response" for maximum oxytocin amount and uterine rupture, with a uterine rupture rate of 2.07% (adjusted odds ratio, 2.98; 95% CI 1.51-5.90) at the highest dosages. CONCLUSION: In VBAC attempts, a dose-response relationship of maximum oxytocin and uterine rupture exists. These results provide evidence for vigilance when higher doses of oxytocin are given to patients who attempt VBAC.

Predicting placental abruption and previa in women with a previous cesarean delivery.

The purpose of this study was to determine if placental abruption or previa in women with a history of a prior cesarean delivery (CD) can be predicted. A retrospective cohort study of pregnant women with previous CD was conducted in 17 centers between 1996 and 2000. Women developing placenta previa or abruption in the subsequent pregnancy were compared with those without these complications. Bivariate and multivariable techniques were used to develop predictive models for placenta previa or abruption. The area under the receiver-operator characteristic curves, sensitivity, specificity, and accuracy of the models were compared. Among 25,076 women with prior CD, there were 361 (15 per 1000 births) with placenta previa and 309 (13 per 1000 births) with abruption. The significant risk factors for these complications include advanced maternal age, Asian race, increased parity, illicit drug use, history of spontaneous abortion, and three or more prior cesarean deliveries. Prediction models for abruption and previa had poor sensitivity (12% and 13% for abruption and previa, respectively). In women with at least one prior cesarean delivery, the risk factors for placental previa and abruption can be identified. However, prediction models combining these risk factors were too inefficient to be useful.

Predicting failure of a vaginal birth attempt after cesarean delivery.

OBJECTIVE: To identify a group of clinical factors that could be used to accurately predict failure in women attempting vaginal birth after cesarean (VBAC). METHODS: We conducted a planned secondary analysis of a retrospective cohort study of women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. We collected information about maternal history and outcomes of the index pregnancy. We used univariable and multivariable statistical methods to develop a multivariable prediction model for the outcome of VBAC failure. RESULTS: A total of 13,706 patients attempted VBAC, with a failure rate of 24.5%. Six variables were significantly associated with VBAC failure in our final logistic regression model: gestational age at delivery, maternal age, maternal race, labor type (spontaneous, augmented, or induced), history of vaginal delivery, and cephalopelvic disproportion or failed induction (combined variable) as prior cesarean indication. The area under the receiver operating characteristics curve is 0.717. To achieve a sensitivity of approximately 75%, a false-positive rate of approximately 40% would result. CONCLUSION: Our results indicate that significant clinical variables (prelabor and labor) cannot reliably predict VBAC failure. LEVEL OF EVIDENCE: II.

Vaginal birth after caesarean delivery: does maternal age affect safety and success?

To estimate maternal age effects on the rates of vaginal birth after caesarean delivery (VBAC), the related maternal complications and patient election to attempt VBAC, we conducted a secondary analysis of a retrospective cohort study of women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. We used bivariable and multivariable analyses to assess the association between maternal age and the study outcomes. A total of 25 005 patients were included, of whom 13 706 (54.81%) elected to attempt VBAC. After controlling for several confounding variables, using ages 21-34 years as the referent group, women aged 15-20 years were 27% less likely to have a failed VBAC attempt (OR = 0.73 [0.62, 0.87], P < 0.001). Analysing maternal age as a dichotomous variable, women who were of advanced maternal age (>or=35 years) were more likely to experience an unsuccessful trial of labour (OR = 1.14 [1.03, 1.25], P = 0.009). In addition, women >or=35 years of age had 39% more risk of experiencing one of the VBAC-related operative complications (OR = 1.39 [1.02, 1.89], P = 0.039). As women increase in age, they are less likely to attempt VBAC and more likely to have an unsuccessful labour trial. While teenage patients do not appear to be at increased risk for VBAC-related complications, patients of advanced maternal age do show an increase in composite VBAC-related operative complication rates.

Can uterine rupture in patients attempting vaginal birth after cesarean delivery be predicted?

OBJECTIVE: This study was undertaken to use multivariable methods to develop clinical predictive models for the occurrence of uterine rupture by using both antepartum and early intrapartum factors. STUDY DESIGN: This was a planned secondary analysis from a multicenter case-control study of uterine rupture among women attempting vaginal birth after cesarean (VBAC) delivery. Multivariable methods were used to develop 2 separate clinical predictive indices--one that used only prelabor factors and the other that used both prelabor and early labor factors. These indices were also assessed with the use of Receiver operating characteristic curves. RESULTS: We identified 134 cases of uterine rupture and 665 noncases. No single individual factor is sufficiently sensitive or specific for clinical prediction of uterine rupture. Likewise, the 2 clinical predictive indices were neither sufficiently sensitive nor specific for clinical use (receiver operating characteristic curve [area under the curve] 0.67 and 0.70, respectively). CONCLUSION: Uterine rupture cannot be predicted with either individual or combinations of clinical factors. This has important clinical and medical-legal implications.

Is vaginal birth after cesarean (VBAC) or elective repeat cesarean safer in women with a prior vaginal delivery?

OBJECTIVE: This study was undertaken to determine whether vaginal birth after cesarean (VBAC) or elective repeat cesarean delivery is safer overall for a woman with a prior vaginal delivery. STUDY DESIGN: This retrospective cohort study of pregnant women from 1996 to 2000 who had a prior cesarean delivery, was conducted in 17 centers. Trained nurses extracted historical and maternal outcome data on subjects by using standardized tools. This planned secondary analysis examined the subcohort that had also previously undergone a vaginal delivery, comparing those who underwent a VBAC trial with those who elected to have a repeat cesarean delivery. Outcomes included uterine rupture, bladder injury, fever, transfusion and a composite (uterine rupture, bladder injury, and artery laceration). We performed bivariate and multivariable analyses. RESULTS: Of 6619 patients with a prior cesarean delivery who had also had a prior vaginal delivery, 5041 patients attempted a VBAC delivery and 1578 had an elective cesarean delivery. Although there was no significant difference in uterine rupture or bladder injury between the two groups, women who underwent a VBAC attempt were less likely to experience the composite adverse maternal outcome, have a fever, or require a transfusion. CONCLUSION: Among VBAC candidates who have had a prior vaginal delivery, those who attempt a VBAC trial have decreased risk for overall major maternal morbidities, as well as maternal fever and transfusion requirement compared with women who elect repeat cesarean delivery. Physicians should make this more favorable benefit-risk ratio explicit when counseling this patient subpopulation on a trial of labor.

Safety and success of vaginal birth after cesarean delivery in patients with preeclampsia.

The objective of this study was to determine if preeclampsia (PRE) or gestational hypertension (GH) affects the rate of success of vaginal birth after cesarean delivery (VBAC), VBAC-related complications, or patient election to attempt VBAC. We performed a retrospective cohort study of all women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. Demographic, medical, and obstetric history, complications, treatment, and index pregnancy outcome information was collected on all patients in the database. Bivariate analysis and multivariable logistic regression were used to assess the independent association between GH and PRE and the rate of success of VBAC, VBAC-related complications, or patient election to attempt VBAC. A total of 25,005 patients were registered in the database. 13,706 (54.81%) attempted VBAC and 11,299 (45.19%) elected repeat cesarean delivery. After adjusting for confounding variables using multivariable logistic regression, patients with PRE were more likely to fail VBAC (relative risk [RR], 1.56; 95% CI, 1.22 to 2.00). Patients with GH were less likely to attempt VBAC (RR, 0.39; 95% CI, 0.34 to 0.46). A total of 304 (1.46%) patients had a uterine rupture. The VBAC group had a rupture rate of 0.93% and the elective cesarean group had a rupture rate of 0.04%. There was no difference in uterine rupture rates between the cohorts. Patients with gestational hypertension were less likely to attempt a VBAC. Patients with PRE, if they attempted a VBAC trial, had a higher VBAC failure rate. Patients with PRE or GH do not have increased uterine rupture rates. These findings can be used to improve mode of delivery counseling for VBAC candidate patients with preeclampsia.

Maternal complications with vaginal birth after cesarean delivery: a multicenter study.

OBJECTIVE: This study was undertaken to determine incidence and risk factors for uterine rupture in women attempting vaginal birth after cesarean delivery (VBAC) in a wide range of hospital settings. STUDY DESIGN: We performed a case-control study nested within a cohort of women who have had a prior cesarean to determine the incidence and risk factors for uterine rupture in women attempting VBAC. RESULTS: The incidence rate of uterine rupture in those who attempt VBAC was 9.8 per 1000. A prior vaginal delivery was associated with a lower risk of uterine rupture (adjusted odds ratio [OR] = 0.40, 95% CI 0.20-0.81). Although prostaglandins alone were not associated with uterine rupture, sequential use of prostaglandin and pitocin was associated with uterine rupture (adjusted OR = 3.07, 95% CI 0.98-9.88). CONCLUSION: Women with a prior cesarean should be offered VBAC, and women with a prior cesarean and prior vaginal delivery should be encouraged to VBAC. Although other studies have suggested that prostaglandins should be avoided, we suggest that inductions requiring sequential agents be avoided.

Vaginal birth after cesarean (VBAC) attempt in twin pregnancies: is it safe?

OBJECTIVE: The purpose of this study was to compare the rate of vaginal birth after cesarean (VBAC) attempt, VBAC failure, and major maternal adverse outcomes in women with a previous cesarean with twin or singleton pregnancies. STUDY DESIGN: This was a multicenter retrospective cohort study between the years 1996 and 2000. Subjects were identified by ICD-9 code. Trained research nurses collected medical record data on the outcome of VBAC attempts, and clinical outcomes, including uterine rupture and major operative injuries. We used bivariate and multivariable techniques to assess the association between twins and the outcomes. RESULTS: Of 25,005 patients with at least 1 previous cesarean, there were 535 twin pregnancies and 24,307 singleton pregnancies. Compared with patients with singleton gestations, patients with twins were less likely to attempt a VBAC (adjusted odds ratio [AOR] 0.3, 95% CI 0.2-0.4), but no more likely to have a VBAC failure (AOR 1.1, 95% CI 0.8-1.6), a uterine rupture (AOR 1.2, 95% CI 0.3-4.6), or a major maternal morbidity (AOR 1.6, 95% CI 0.7-3.7). CONCLUSION: Women with twin gestations are less likely to attempt a VBAC, but they are no more likely to fail a VBAC trial or experience a major morbid event compared with women with singleton gestations.