The rate of operative vaginal delivery in the United States was 9% in 2005, a 42% reduction over the previous decade.1 The reasons for this decline are not fully understood but may include concern for fetal injury, such as skull fracture and intracranial hemorrhage, and maternal tissue trauma, a decrease in the training and experience of obstetricians in the use of forceps and vacuum, and an overall increase in cesarean-delivery rates. The potential for harm with the use of obstetric forceps and vacuum has been recognized since their introduction into practice. Until the development of cesarean delivery as a safe alternative, however, trauma related to the use of obstetric forceps was unavoidable. As cesarean delivery became more widely available in the early to mid-20th century, the use of forceps and vacuum for the more difficult cases of cephalopelvic disproportion decreased and new practices were developed to minimize morbidity and maximize safety of operative vaginal delivery. The concept of a trial of forceps or vacuum has evolved into one such practice. This approach, first developed in the 1950s, stresses the importance of the ability to perform an immediate cesarean delivery in those cases in which an initial attempt at operative vaginal delivery fails. The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Maternal-Fetal Medicine Units Network observational study of cesarean delivery offered an opportunity to study maternal and neonatal outcomes in women undergoing cesarean delivery after a trial of operative vaginal delivery and compare these outcomes with those of women undergoing second-stage cesarean without such intervention.3
The objective of our study was to compare maternal and neonatal outcomes in women undergoing second-stage cesarean delivery after a trial of operative vaginal delivery with those of women undergoing second-stage cesarean delivery without such an attempt.
MATERIALS AND METHODS
This is a secondary analysis of the Maternal-Fetal Medicine Units Network cesarean registry. This registry was an observational study conducted by the NICHD to assess several contemporary issues related to cesarean delivery. Between January 1, 1999, and December 31, 2000, all women undergoing cesarean delivery with a neonate of at least 500 g or 20 weeks of gestation at participating centers were ascertained prospectively. Each of the 13 centers participating in this NICHD Maternal-Fetal Medicine Units Network study obtained institutional review board approval before enrollment.
The primary outcomes for the cesarean-delivery registry have been reported previously.2 In brief, detailed information regarding medical and obstetrical history, intrapartum course, postpartum complications, and neonatal outcomes was abstracted directly from maternal and neonatal charts by specially trained and certified research nurses. All data were entered into a computerized database without patient identifiers and transmitted electronically to the George Washington University Biostatistics Center on a weekly basis. Electronic edit reports were generated each week and transmitted back to each center for correction or identification.
For this secondary analysis, maternal and neonatal outcomes of women who underwent second-stage cesarean delivery after an attempted operative vaginal delivery were compared with those of women who underwent second-stage cesarean delivery without such an attempt. This analysis was limited to singleton, nonanomalous gestations with vertex presentation. Demographics, labor characteristics, and the indication for the cesarean delivery were compared in the two groups. The indication for the operative vaginal delivery attempt was not available.
Maternal outcomes examined included the need for a blood transfusion, endometritis (defined as a persistent postpartum temperature of 37.8°C or higher with uterine tenderness and no other infection), wound complications (defined as infection at the skin-incision site, seroma, or hematoma), and maternal death. We compared the type of anesthesia used, including regional and general. Neonatal outcomes examined included umbilical artery pH less than 7.0, Apgar score of 3 or less at 5 minutes, seizures within 24 hours of birth, hypoxic ischemic encephalopathy, stillbirth, skull fracture, and neonatal death. We also looked at fetal injury and intracranial hemorrhage in the neonates diagnosed with hypoxic ischemic encephalopathy.
A separate data-collection form was completed for all neonates who had a clinical diagnosis of hypoxic ischemic encephalopathy or any of the following: seizures, cardiopulmonary resuscitation during the first 24 hours of life, umbilical cord pH value below 7.0, head injury at term, 5-minute Apgar score of less than 4, and maternal uterine rupture. All instances of hypoxic ischemic encephalopathy underwent secondary review by a local study investigator.
Statistical analyses included the Wilcoxon rank-sum test for continuous variables and the χ2 test or Fisher exact test for categorized variables. Unless otherwise noted, the response rate for the variables was 95% or greater. Nominal two-sided P values are reported, with statistical significance considered as P<.05. No adjustment was made for multiple comparisons. SAS software (SAS Institute, Cary, NC) was used for analysis.
During the 2-year study period, there were 29,612 singleton, vertex, nonanomalous pregnancies for which cesarean delivery was performed. A second-stage cesarean delivery was performed for 3,189 patients. Of these women, 640 underwent an attempt at operative vaginal delivery before the cesarean delivery—395 with forceps, 182 with vacuum, and 63 with both. A second-stage cesarean delivery without an attempt at operative delivery was performed for 2,549 patients.
Table 1 shows selected demographic and pregnancy characteristics. Women undergoing an attempt at operative vaginal delivery were younger, more likely to be nulliparous, and less likely to have undergone a previous cesarean delivery. Although birth weight was different between the groups, this difference was slight and not clinically significant. Table 2 shows labor characteristics between the groups. The use of labor epidural, oxytocin, and amniotomy was similar between the groups. The interval from admission to delivery was longer in the no-attempt group, but this difference was less than 1 hour and was not clinically significant. The primary indication for cesarean delivery was also different, with more women undergoing cesarean delivery for a nonreassuring fetal heart rate in the group that underwent an attempt at operative vaginal delivery (18.0% compared with 13.9%, P=.01).
Maternal outcomes are shown in Table 3. Women who underwent an attempt at operative vaginal delivery were more likely to have wound complications and to undergo general anesthesia due to failed regional anesthesia. An increased need for blood transfusion in the attempted-operative-vaginal-delivery group was seen; however, this was not significant. No maternal deaths occurred in the cohort.
Table 4 shows neonatal outcomes in the two groups. The attempted-operative-vaginal-delivery group had an increased incidence of umbilical artery pH less than 7.0. This information was not recorded for 57% of the neonates. The frequency of a neonate with an Apgar score of 3 or less at 5 minutes, seizure, or hypoxic ischemic encephalopathy was greater in the attempted-operative-vaginal-delivery group. Stillbirth and neonatal death were not different in the two groups. There were two cases of skull fracture in the attempted-vaginal-delivery group, but none were seen in the no-attempt group (0.31% compared with 0, P=.04). Further examination of the cases of hypoxic ischemic encephalopathy revealed that all 10 cases involved some level of concern about the fetal heart rate. In 2 of the 10 cases, there was a prolapsed cord, six cases had nonreassuring fetal heart rate listed as the primary reason for delivery, and four cases had nonreassuring heart rate listed as a secondary indication for delivery. There were no cases of fetal injury, including intracranial hemorrhage and skull fracture, in these 10 cases.
There were 733 (23%) cases that had a nonreassuring fetal heart rate tracing listed as the primary or secondary indication for cesarean. More than two thirds (69%) of the adverse neonatal outcomes were in this group, for an incidence of 5.7%. In the remaining 2,456 cases, there were 19 cases of adverse neonatal outcome, for an incidence of 0.8%. Table 5 shows the neonatal outcomes in the two groups, excluding those cases without a primary or secondary indication of a nonreassuring fetal heart rate. There were no longer any differences between the two groups.
We found that an unsuccessful attempt at operative vaginal delivery was associated with a greater rate of adverse maternal and neonatal outcomes relative to second-stage cesarean delivery without such an attempt. Adverse neonatal outcomes associated with an attempt at operative vaginal delivery included an Apgar score of 3 or less at 5 minutes, an umbilical artery cord pH of less than 7.0, seizures within 24 hours of birth, and hypoxic ischemic encephalopathy. Although the incidence of an umbilical artery cord pH less than 7.0 was greater in the attempted-operative-vaginal-delivery group, this may reflect the indication for obtaining the umbilical artery cord gas rather than a true increase in the incidence of this outcome. The cases of hypoxic ischemic encephalopathy showed no evidence of injury to the fetus secondary to the unsuccessful attempt, including skull fracture and intracranial hemorrhage. The increased maternal morbidity seen included wound complications and failed regional anesthesia resulting in the need for intubation and general anesthesia. We also found that the indication for cesarean delivery was different in the two groups, with intervention for a nonreassuring fetal heart rate being more common in the operative-vaginal-delivery group. Excluding those cases with an indication for cesarean delivery of a nonreassuring fetal heart rate eliminated the differences seen in neonatal outcomes in the two groups. Indeed, all of the cases of hypoxic ischemic encephalopathy had evidence of fetal jeopardy before delivery.
Historically, a failed forceps or vacuum delivery has been associated with unacceptably high maternal and neonatal morbidity. Freeth in 1950 reported a fetal mortality rate of 38% and a maternal mortality rate of 2% in cases of failed forceps operations.4 Similarly, Law in 1953 reviewed 37 cases of failed forceps operations and found perinatal mortality to be 24.3% and maternal morbidity to be 27%. There were no maternal deaths.4 These reports occurred during a time of very low cesarean-delivery rates when vaginal delivery was pursued regardless of the fetal consequences. In response to these reports and others, Douglas and Kaltreader introduced the concept of a trial of forceps.5 In their article, they describe a new approach to forceps, which, briefly, consisted of the correction of abnormality of position and gentle traction with the forceps. If progress with the forceps was not obtained immediately, the patient was prepped for an urgent cesarean delivery. This article marked the beginning of a new era in the use of obstetric forceps and came about in part because of the increased safety and use of cesarean delivery.
As the concept of a trial of forceps or vacuum became accepted, reports supporting this approach began to appear in the literature. Boyd in 1986 reported that the rates of adverse outcomes, including asphyxia in neonates born after an unsuccessful forceps attempt, were not different in neonates born by cesarean delivery for failure to progress.6 Both groups of neonates were at significantly higher risk of these outcomes, however, than were neonates who were delivered spontaneously. Revah et al report no significant difference in neonatal outcomes when comparing neonates born after a failed forceps attempt, vacuum attempt, or both with those delivered by women undergoing a cesarean delivery without such an attempt.7 These authors were careful to point out that study design is important in interpreting studies of this subject owing to the multiple confounders present in these cases, most importantly the indication for which the forceps or vacuum attempt is made. Towner et al made this point in their 1999 study of the effect of delivery mode on neonatal intracranial injury.8 They reported that cesarean delivery performed during labor as well as forceps and vacuum extraction were associated with an increased risk of intracranial hemorrhage when compared with spontaneous vaginal delivery. This association was driven by abnormal labor, that is, the method of delivery was not the primary factor associated with intracranial hemorrhage, but the indication for delivery was.
Although the concept of a trial of operative vaginal delivery with availability of immediate cesarean delivery for those cases that fail has become well established, the overall use of operative vaginal delivery has declined greatly.1 Murphy recently has raised concerns about the wisdom of such a decline owing to the morbidity associated with second-stage cesarean delivery. She reports increased risks of maternal hemorrhage, prolonged hospital stay, increased risk of bladder trauma, and extensions of the uterine incision into the broad ligament and vessels with second-stage cesarean delivery.9,10 Our recent report on the morbidity associated with second-stage cesarean delivery as compared with first-stage cesarean delivery also found increased maternal morbidity, including uterine-incision extension and incidental cystotomy as well as an increase in fetal injury, primarily due to laceration.11 The existing data therefore suggest that the use of operative vaginal delivery in the properly selected patient minimizes maternal risk without increasing neonatal morbidity.
Our study examined the consequences of an unsuccessful operative vaginal delivery attempt in the context of second-stage cesarean delivery. We are unable to make a definitive statement on safety because we do not have information on the women who had a successful attempt at operative vaginal delivery. In addition, the indications for which the operative vaginal delivery was attempted were unavailable. We are able to say however, that the neonates with the most serious adverse outcome measured, hypoxic ischemic encephalopathy, did not appear to suffer injury directly attributable to the instrument, such as intracranial hemorrhage or skull fracture. Furthermore, cases of adverse neonatal outcomes were strongly associated with evidence of fetal jeopardy before the attempt at operative vaginal delivery and may have little to do with the route of delivery itself. Our findings suggest that the circumstances leading to operative second-stage delivery play a significant role in the ultimate outcome of the neonate. In the absence of a nonreassuring fetal heart rate tracing, an attempt at operative vaginal delivery before performing a cesarean delivery was not associated with adverse neonatal outcomes.
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