Neural tube defects (NTDs) are the second most prevalent neonatal anomaly in the United States and occur on average in 1 in 1,000 deliveries.1 These defects result from incomplete fusion of the neural tube during embryogenesis. In addition to the considerable health care resources required for the management of the morbidity associated with this condition, the emotional and psychosocial impact on the infant and family can be tremendous. Generally speaking, survival and degree of physical handicap depend on the level of the spinal segment involved, the severity of the lesion, and associated anomalies.2 The number of infants born with NTDs has decreased in the last 3 decades for 2 main reasons. First, the widespread use of maternal serum alpha-fetoprotein screening programs and the availability of obstetric sonography have made antenatal detection of this condition the rule rather than the exception, thus allowing parents the option of terminating the pregnancy. Secondly, the appreciation of the role of folic acid therapy in the prevention of NTDs has allowed primary prevention strategies such as fortification of food and mineral supplements with folic acid.3–6 Cesarean delivery has been advocated as being superior to vaginal delivery in preventing further neurologic damage in fetuses with antenatally diagnosed myelomeningocele.7–12 It has been posited that the mechanical forces of labor and vaginal delivery may aggravate already compromised exposed nerve roots. These studies, however, have had critical methodological flaws, including poor design, selection bias, and lack of long-term follow-up data.7–12
The aim of this study was to evaluate whether long-term motor function and ambulatory status in infants with myelomeningocele is better if elective cesarean delivery is performed rather then allowing trial of labor.
MATERIALS AND METHODS
The Alfred I. duPont Hospital for Children in Wilmington is the largest pediatric care facility in the state of Delaware. It is the pediatric referral center for most of the state as well as hospitals affiliated with the Thomas Jefferson University in Philadelphia, Pennsylvania. The Spinal Dysfunction Center provides a central site for the care of children with spinal injury. The center is run by a pediatric rehabilitation physician and nursing team who coordinate the care of these infants among various multispecialty services (eg, neurosurgery, orthopedic, urology, and social work). A clinical database was used to identify all patients seen at the center between 1995 and 2000. The charts of all those with the diagnosis of myelomeningocele were reviewed. The ages of patients ranged from 2 to 21 years.
When myelomeningocele was diagnosed in an infant at Thomas Jefferson University, fetal karyotyping, echocardiography, and monthly sonographic estimation of fetal growth was offered. Mode of delivery was at the discretion of the patient and her obstetrician. After repair of the myelomeningocele at Thomas Jefferson University Hospital, infants received all subsequent care at Alfred I. duPont Hospital.
The Institutional Review Boards at both Thomas Jefferson University and Alfred I. duPont Hospital for Children approved this study. Neonatal and pediatric records were reviewed for gestational age at delivery, birthweight, anatomical level of lesion, and initial (0–6 months) and long-term (10 years or longer) motor level. Three categories of ambulation status were defined: independently ambulant, ambulant with assistance, or wheelchair-bound at age 2 and 10 years. These categories were correlated with plan of delivery: elective cesarean versus trial of labor. A sample size calculation was made by using the data of Luthy et al11 comparing means of motor-anatomical–level differences in 2 comparison groups (exposure to labor and type of delivery). A total sample size of 48 patients is required to achieve 80% power (2-tailed, α = .05 and β = .20) to detect an effect size of 2.2 on motor level of paralysis and a standard deviation of 2.65, as reported by Luthy et al.11 Categorical variables were analyzed by using the χ2 or Fisher exact test; continuous variables were analyzed by using the t test. A P value of less than 0.05 was considered significant. Logistic regression analysis, controlling for motor level of the neural tube defect, was used to evaluate the association between plan of delivery and ambulation status at age 2 and 10 years. Statistical analysis was performed by using SAS 8.2 (SAS Institute Inc, Cary, NC) and SPSS 10.1 for Windows (SPSS Inc, Chicago, IL).
Of the 106 patients whose charts were reviewed, 87 (82%) had all the required data and follow-up at 2 and 10 years, respectively. There were 44 patients in the elective cesarean group and 43 patients in the trial of labor group. All patients with an antenatal diagnosis of myelomeningocele (n = 23) were delivered by elective cesarean. The remaining 21 underwent elective cesarean for the following reasons: repeat (n = 13), breech (n = 6), hydrocephalus (n = 1), and twin gestation (n = 1). In the trial of labor group, 33 patients were successful, and 10 patients had cesarean delivery for obstetric indications. The indications for these nonelective cesarean deliveries included fetal distress (n = 1), failed induction of labor (n = 2), and failure to progress (n = 7). There were no significant differences in gestational age at delivery (37.5 ± 2.0 weeks versus 38.4 ± 2.5 weeks, P = .11) or birthweight (3,138 ± 587 g versus 3,327 ± 628 g, P = .21) between the elective cesarean and trial of labor groups (Table 1). There was a statistically significant difference between the groups when anatomical, initial, and current motor levels were compared. (Table 1). Patients in the elective cesarean group were overall less likely to be ambulatory when compared with those in the labor group at 2 years (independent 7% versus 28%, with assistance 63% versus 65%, or wheelchair-bound 30% versus 7%, P = .003) and at 10 years (independent 5% versus 21%, with assistance 30% versus 54%, or wheelchair-bound 65% versus 25%, P < .001) (Tables 2 and 3).
No statistically significant difference was identified with logistic regression analysis when the elective cesarean group was compared with the trial of labor group in the following categories: at age 2, ambulating with assistance rather than independently (odds ratio [OR] 2.5; 95% confidence interval [CI] 0.5, 16.9), being wheelchair-bound rather than ambulating with assistance (OR 1.9; 95% CI 0.3, 14.3); at age 10 years, ambulating with assistance rather than independently (OR 1.9; 95% CI 0.3, 22.9), being wheelchair-bound rather than ambulating with assistance (OR 2.9, 95% CI 0.8, 10.5).
The anatomical level was significantly associated with ambulation status. An increase of 1 spinal segment in anatomical level translated into a 52–56% decrease in the likelihood of more severe ambulation status. By using logistic regression and controlling for motor level of myelomeningocele, no significant association was observed between elective cesarean versus trial of labor and ambulatory status at ages 2 and 10 years.
Chervenak et al7 reported on a series of 9 cases of myelomeningocele diagnosed in fetuses. Four of these cases were detected antenatally, and these patients were delivered by elective cesarean. Three of the 4 infants survived and were followed up for 5–17 months. The authors, without providing information about the remaining 5 infants or long-term follow-up data regarding the 3 survivors after elective cesarean delivery, recommended that cesarean delivery be offered as a potential beneficial procedure because there was “… no clinical data demonstrating that vaginal delivery can be nontraumatic and nondetrimental… .”
Cochrane et al8 retrospectively studied the effect of labor and delivery on spinal cord function and ambulation in 208 patients with myelomeningocele. The mode of delivery did not appear to be associated with ambulatory status except in neonates presenting as breech, where they theorized that neurological function could be aggravated by vaginal delivery. They cautioned that, in their series, injury to the placode was not invariable with vaginal delivery and did occur even with cesarean delivery.
Hadi et al,9 reporting retrospectively on a series of 8 neonates delivered vaginally from a vertex presentation, described no cases of rupture of myelomeningocele sac and suggested that vaginal delivery may be safe if the myelomeningocele sac diameter does not exceed 4 cm. Sakala et al,10 in a retrospective comparison of 20 infants delivered vaginally with 15 delivered by cesarean, concurred with Hadi et al9 that cesarean delivery did not appear to confer any benefit to infants with myelomeningocele in terms of immediate or long-term outcome, and perhaps lesions larger than 6 cm in diameter were more likely to rupture during labor.
Luthy et al11 reported on cesarean delivery before the onset of labor and subsequent motor function. Forty-seven fetuses in whom isolated myelomeningocele was antenatally diagnosed and with normal karyotype and no severe hydrocephalus were followed up prospectively and offered cesarean delivery. These were compared with a historical cohort of 103 fetuses in whom myelomeningocele was diagnosed after birth who were delivered after trial of labor. The authors concluded that for fetuses with myelomeningocele, normal karyotype, and lack of severe hydrocephalus, cesarean delivery before the onset of labor may result in improved motor function. This conclusion begs the obvious question: Had that same cohort of infants been allowed trial of labor, would their outcome not have been just as good? Antenatal diagnosis, normal karyotype, absence of other anomalies including severe hydrocephalus, and delivery and care in a modern tertiary center with an awaiting multispecialty team would all be expected to be associated with a better outcome regardless of timing of delivery relative to labor. The specter of trauma to spinal nerves during labor was raised without being explored.
In a retrospective study of infants with myelomeningocele, Merrill et al12 compared outcome in 20 who were delivered vaginally to 15 who were delivered by cesarean. They found no difference in long-term motor function between the two groups. In our view, this report has the strongest study design to date and should thus be considered the most instructive. It is also the most relevant to contemporary obstetrics for the following reasons: A similar majority of infants in both groups had the benefit of antenatal diagnosis, birth at a tertiary care center, early surgical repair of the myelomeningocele, and related complications and multidisciplinary outpatient follow-up.
The goal of our study was to evaluate whether elective cesarean delivery, when compared with trial of labor, was associated with better long-term ambulation status in infants with myelomeningocele. This study has several important strengths. It is the longest follow-up period reported to date on such infants in the United States, according to a search of MEDLINE (1966 to January 2003; search terms: “neural tube defect,” “myelomeningocele,” “spina bifida,” and “mode of delivery”). Motor function was evaluated by using a parameter that is readily understood by medical personnel as well as the lay public and by using a large sample size. We did not find that elective cesarean delivery provided any clear benefit in long-term ambulation status when compared with trial of labor in infants born with myelomeningocele who were being cared for at a specialized medical facility. Our data also provide support to the commonly held impression that as these children grow older they are more likely to use a wheelchair or ambulate with support than to ambulate independently. This should not necessarily be seen as evidence of worsening neurological status. Because wheelchair-accessible amenities are common today, it may often be more convenient for the older child or young adult to use a wheelchair rather than braces. Our sample size of 87 gave us 97% power (α = .05) to detect an effect size of 2.2 on motor level of paralysis and a standard deviation of 2.65, as reported by Luthy et al,11 the most commonly cited study for clinical practice today.
There is unanimous agreement that motor function is largely dependent on the anatomical level of myelomeningocele. We contend that it is also the absence of other anomalies (including severe hydrocephalus) and the timely availability of a skilled medical team (including for long-term care), not the mode of delivery, that determine ultimate outcome. The ambulation status and accompanying complications of myelomeningocele may well be a manifestation of abnormal neural development.13 One may also conclude the following: 1) the theory of labor induced or aggravated placode injury remains unsubstantiated; 2) although, intuitively, the larger the myelomeningocele sac the more likely that rupture or leakage will occur during delivery, it is unclear if this is of any clinical significance; 3) injury to the myelomeningocele sac may occur regardless of mode of delivery.
Because the putative benefits of elective cesarean delivery in this context accrue almost entirely to the fetus, it is important that the benefits to this practice be evidence based. Anesthetic and thromboembolic complications are among the most significant risk factors for maternal mortality in the United States today. Both of these are more frequent after cesarean delivery. In the spirit of “first do no harm,” the onus should be on those who advocate elective cesarean delivery to demonstrate convincingly that this practice has merit over trial of labor rather than the reverse.
We conclude, therefore, that until a prospective randomized trial indicates otherwise, the preponderance of current scientific literature suggests that the optimal delivery management for infants with myelomeningocele is to allow trial of labor unless obstetric indications suggest otherwise.
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