Objective
The objective of the study was to assess the outcome of trial of labor after cesarean (TOLAC) in women with past failed operative vaginal delivery (OVD).
Study Design
A retrospective study of all women who underwent cesarean section (CS) because of a failed OVD in a tertiary medical center between 1996 and 2011. Women who had a subsequent delivery were identified, and the outcome of subsequent delivery was analyzed.
Results
Overall, 533 women underwent CS because of failed OVD during the study period. A total of 204 women (38.3%) had a subsequent delivery, of whom 93 (45.6%) had a TOLAC and 111 (54.4%) had a repeat elective CS. The success rate in the TOLAC group was 61.3% (n = 57). The most common indication for repeat CS was lack of progress (72.3%) among the 36 women in whom TOLAC failed (38.7%). The rate of postpartum hemorrhage and prolonged maternal hospitalization was lower in the TOLAC group than in the repeat CS group (2.2% vs 10.8%, P = .02, and 0% vs 8.1%, P = .005). There were no cases of rupture or dehiscence of the uterine scar. Factors associated with failed TOLAC were the occiput-posterior position and prolonged the second stage as the indication for OVD in the index pregnancy, maternal age older than 30 years at the time of subsequent delivery, and a birthweight in the subsequent pregnancy that is higher than the birthweight in the index pregnancy.
Conclusion
TOLAC in women who underwent a previous CS because of a failed OVD is associated with a relatively high success rate compared with the reported success rates among women with past CS during the second stage of labor. This information and the risk factors for TOLAC failure can be used when counseling these women regarding mode of delivery in subsequent pregnancy.
Trial of labor after previous cesarean delivery (TOLAC) remains a matter of debate. This controversy is reflected by the dramatic decrease in the rate of vaginal birth after cesarean (VBAC) in the United States during recent years from 28.3% in 1996 to 9.2% in 2004. In the face of this trend, in 2010 the National Institute of Health Panel called organizations to facilitate access to TOLAC after recognizing TOLAC as a reasonable option for many women with 1 prior low transverse uterine incision. Clearly, one of the measures that can assist clinicians in counseling women regarding TOLAC is improved prediction of the likelihood of successful VBAC.
Previous studies identified a considerable number of factors that are associated with successful VBAC, including the indication for cesarean section (CS) in the previous delivery. One specifically challenging scenario is the consultation regarding TOLAC to women for whom the previous CS followed a failed trial of operative vaginal delivery (OVD) using vacuum or forceps. Unfortunately, data regarding the likelihood of successful VBAC in this context are extremely limited. Only one previous study, conducted approximately 15 years ago, addressed this specific question. However, that study included women with past CS because of failed second stage of labor in general and was not focused on women with past failed OVD, and the number of women with past failed OVD was relatively small (n = 55).
Intuitively, a history of failed OVD would be expected to be associated with low VBAC success rates because of concern that such a history might indicate pelvic pathology. Nevertheless, failure of OVD may be related in many cases to relative or nonrecurring factors such as position of the fetal head, fetal macrosomia, or errors in the application of the vacuum cap or in the technique of OVD. Other factors that have been found to be associated with failed OVD include advanced maternal age, nulliparity, maternal obesity, induction of labor, and lack of prenatal care.
Prompted by the lack of data on the outcome of TOLAC in these cases, we aimed to assess the outcome of TOLAC in women with past failed OVD and to identify risk factors for TOLAC failure.
Materials and Methods
Study population
This was a retrospective study of all women who underwent CS following a failed OVD in a university-affiliated tertiary medical center between 1996 and 2011 (index delivery, Figure ). Those women who had a subsequent delivery in the same medical center were identified, and the outcome and mode of delivery in the subsequent delivery were assessed ( Figure ).
The characteristics of the index pregnancy and the outcome of subsequent pregnancy of women who had a TOLAC were analyzed and were compared with those of women who underwent an elective repeat CS in the subsequent pregnancy. In addition, to identify factors associated with TOLAC failure in this group of women, the characteristics of women who underwent a successful TOLAC (ie, those who eventually indeed delivered vaginally) in the subsequent pregnancy were compared with those of women in whom TOLAC failed (ie, those who eventually delivered by repeat CS).
Pregnancies complicated by any of the following conditions were excluded from the study group: multiple gestations, a history of a previous CS at the time of the index delivery, gestational age at delivery less than 37 weeks at the index or subsequent pregnancies, vertical uterine incision at the time of CS in the index pregnancy, the need for an urgent CS prior to the onset of labor in the subsequent pregnancy because of maternal and/or fetal complications, or major fetal anomalies. The study protocol was approved by the local institutional review board.
Data collection
Cases were initially identified using the comprehensive computerized perinatal database maintained in our medical center. Patient files and the electronic records were reviewed for demographic data, obstetrical history, data on index and subsequent pregnancies, labor and delivery data for index and subsequent pregnancies, and maternal and short-term neonatal outcome in the index and subsequent pregnancies.
Definitions
The indications for OVD in our center are prolonged second stage, as stipulated in the guidelines of the American College of Obstetricians and Gynecologists for nulliparous and multiparous women and nonreassuring fetal heart rate (NRFHR). We perform only low or outlet OVD. Vacuum extraction is considered as the method of choice in our institution when OVD is indicated. Failed vacuum extraction (VE) is defined as 2 cup detachments or no progression of the fetal head despite appropriate traction.
Respiratory morbidity was defined as any of the following: respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), or need for respiratory support. RDS was diagnosed by the presence of respiratory compromise, the need for administration of exogenous surfactant, and/or radiographic evidence of neonatal pulmonary hyaline membrane disease including atelectasis, air bronchograms, and a diffuse reticulogranular infiltrate.
Neonatal trauma was defined as any of the following factors: cephalohematoma, skull fracture, subdural/cerebral hematoma, intraventricular hemorrhage, or facial-nerve injury.
Data analysis
Data analysis was performed with the SPSS version 19.0 package (SPSS Inc, Chicago, IL). A Student t test and a Mann-Whitney U test were used to compare continuous variables with normal and nonnormal distribution between the groups, respectively. Normality was assessed using the Q-Q plot and the Kolmogorov-Smirnov test. The χ 2 and Fisher exact tests were used for categorical variables. Multivariable logistic regression analysis was used to identify factors associated with failed TOLAC. Variables that were found to be different between the VBAC failure and success groups ( P < .1) in the bivariate analysis as well as variables that were hypothesized to potentially affect the likelihood of success/failure based on clinical grounds were entered to the initial regression model. The forward likelihood ratio method was used for model reduction. Differences were considered significant at P < .05.
Results
Characteristics of the index and subsequent deliveries
Of the 5982 women who underwent a trial of OVD during the study period, 533 (8.9%) underwent CS because of OVD failure ( Figure ). Of these, 204 (38.3%) had a subsequent delivery in our medical center, of whom 93 (45.6%) had a TOLAC and 111 (54.4%) had an elective repeat CS ( Figure ).
Table 1 presents the characteristics of the index delivery (the failed OVD) for women who had a TOLAC or elective repeat CS in their subsequent pregnancy. Women who underwent TOLAC in their subsequent pregnancy were characterized by a lower maternal age and by a higher rate of persistent occiput-posterior (POP) position of the fetal head, epidural analgesia, and a prolonged second stage as the indication for the OVD at the time of the index pregnancy ( Table 1 ).
| Characteristics in index pregnancy | TOLAC in subsequent pregnancy (n = 93) | Elective repeat CS in subsequent pregnancy (n = 111) | P value |
|---|---|---|---|
| Maternal age, y | 26.0 ± 4.9 | 27.6 ± 3.8 | .009 |
| >30 y | 14 (15.1) | 23 (20.7) | .3 |
| Nulliparity | 88 (94.6) | 106 (95.5) | .8 |
| Gestational age at delivery, wks | 40.0 ± 1.5 | 39.6 ± 1.4 | .08 |
| Induction of labor | 19 (20.4) | 21 (18.9) | .8 |
| Past term | 5 (26.3) | 6 (28.6) | .9 |
| PROM | 6 (31.6) | 8 (38.1) | .7 |
| Suspected oligohydramnios | 3 (15.8) | 5 (23.8) | .5 |
| Suspected IUGR | 3 (15.8) | 1 (4.8) | .2 |
| Diabetes | 2 (10.5) | 1 (4.8) | .5 |
| Other | 3 (15.8) | 4 (19.0) | .8 |
| Type of OVD | .3 | ||
| Vacuum | 89 (95.7) | 109 (98.2) | |
| Forceps | 4 (4.3) | 2 (1.8) | |
| Indication for OVD | .002 | ||
| NRFHR | 16 (17.2) | 41 (36.9) | |
| Prolonged second stage | 77 (82.8) | 70 (63.1) | |
| POP position | 16 (17.2) | 6 (5.4) | .007 |
| Epidural analgesia | 75 (80.6) | 69 (62.2) | .004 |
| Birthweight, g | 3332 ± 407 | 3343 ± 361 | .8 |
| >4000 g | 5 (5.4) | 3 (2.7) | .3 |
Table 2 presents the characteristics of the subsequent delivery for women who had a TOLAC or elective repeat CS. Women in the TOLAC group were characterized by a lower maternal age, a shorter interval between index and subsequent delivery, and a higher gestational age at delivery compared with women who underwent an elective repeat CS ( Table 2 ).
| Characteristics in subsequent pregnancy | TOLAC in subsequent pregnancy (n = 93) | Elective repeat CS in subsequent pregnancy (n = 111) | P value |
|---|---|---|---|
| Maternal age, y | 28.5 ± 4.6 | 31.8 ± 3.6 | < .001 |
| >30 y | 30 (32.3) | 71 (64.0) | < .001 |
| Time from index delivery, y | 3.1 ± 1.5 | 3.9 ± 1.7 | .001 |
| Parity | 2 (2-3) | 2 (2-3) | .6 |
| Pregestational diabetes | 2 (2.2) | 1 (0.9) | .5 |
| Chronic hypertension | 1 (1.1) | 1 (0.9) | .9 |
| Gestational diabetes | 4 (4.3) | 3 (2.7) | .5 |
| Preeclampsia | 0 (0.0) | 0 (0.0) | N/A |
| Induction of labor | 0 (0.0) | N/A | N/A |
| Gestational age at delivery, wks | 39.0 ± 1.7 | 38.1 ± 1.3 | < .001 |
| Male fetal sex | 39 (41.9) | 50 (45.0) | .6 |
Outcome of subsequent delivery
Table 3 presents the outcome of the subsequent delivery for women who had a TOLAC or elective repeat CS. The success rate in the TOLAC group was 61.3% (n = 57), of whom 12 women (12.9%) underwent OVD of which none failed ( Table 3 ). Of the 36 women in whom TOLAC failed (38.7%), the most common reason for failure was lack of progress of labor (72.3%) ( Table 3 ). Of the women who underwent elective repeat CS, 79 cases (71.2%) were due to maternal preference, and 25 (22.5%) were due to medical indications including malpresentation, suspected macrosomia, and placenta previa ( Table 3 ).
| Outcome in subsequent pregnancy | TOLAC in subsequent pregnancy (n = 93) | Elective repeat CS in subsequent pregnancy (n = 111) |
|---|---|---|
| Mode of delivery | ||
| Spontaneous delivery | 45 (48.4) | N/A |
| Operative vaginal delivery | 12 (12.9) | N/A |
| Prolonged second stage | 8 (66.7) | N/A |
| Failure | 0 (0.0) | N/A |
| Cesarean section | 36 (38.7) | 111 (100.0) a |
| Lack of progress, first stage | 15 (41.7) | N/A |
| Lack of progress, second stage | 11 (30.6) | N/A |
| NRFHR | 10 (27.8) | N/A |
| Maternal request | N/A | 79 (71.2) |
| Breech | N/A | 13 (11.7) |
| Placenta previa | N/A | 4 (3.6) |
| Macrosomia | N/A | 8 (7.2) |
| Unknown | N/A | 7 (6.3) |
| Episiotomy | 38 (40.9) | N/A |
| Third- or fourth-degree perineal laceration | 0 (0.0) | N/A |
| POP position | 5 (5.4) | N/A |
| Epidural analgesia | 41 (44.1) | N/A |
| Intrapartum fever | 6 (6.5) | N/A |
| Meconium | 11 (11.8) | N/A |
| Postpartum hemorrhage | 2 (2.2) | 12 (10.8) b |
| Dehiscence or rupture of uterine scar | 0 (0.0) | 0 (0.0) |
| Bladder injury | 0 (0.0) | 0 (0.0) |
| Bowel injury | N/A | 0 (0.0) |
| Maternal hospital stay longer than 5 d | 0 (0.0) | 9 (8.1) a |
| Neonatal outcome | ||
| Birthweight, g | 3142 ± 305 | 3241 ± 448 c |
| >4000 g | 0 (0.0) | 8 (7.2) a |
| 5-minute Apgar <7 | 0 (0.0) | 0 (0.0) |
| NICU admission | 5 (5.4) | 7 (6.3) c |
| Respiratory morbidity d | 2 (2.2) | 4 (3.6) c |
| Neonatal birth trauma e | 0 (0.0) | 0 (0.0) |
c Difference is nonsignificant
d TTN, RDS, or the need for respiratory assistance
e Cephalohematoma, skull fracture, subdural/cerebral hematoma, intraventricular hemorrhage, or facial nerve injury.
The rate of postpartum hemorrhage and prolonged maternal hospitalization was lower in the TOLAC group than in the repeat CS group ( Table 3 ). There were no cases of rupture or dehiscence of the uterine scar or other intraoperative complications in either of the groups ( Table 3 ).
There were no significant differences with respect to the short-term neonatal outcome between the TOLAC and the repeat CS groups in terms of Apgar score, admission to the neonatal intensive care unit, respiratory morbidity, or birth trauma ( Table 3 ). The rate of macrosomia was significantly higher in the elective repeat CS group ( Table 3 ).
Risk factors for failed TOLAC
To identify the factors that are associated with failed TOLAC, the characteristics at the time of the index and subsequent pregnancies of women who underwent successful (n = 57) vs failed (n = 36) TOLAC were compared ( Table 4 ). Women in the failed TOLAC subgroup were characterized by a higher maternal age in the index and subsequent deliveries, a higher rate of trial of forceps (rather than vacuum) delivery, and a lower rate of the POP position of the fetal head in the index delivery, and by a neonatal birthweight that was higher in the subsequent pregnancy than in the index pregnancy ( Table 4 ).
