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ORIGINAL RESEARCH |
From the Divisions of Maternal Fetal Medicine and Research in Reproductive Health, Department of Obstetrics and Gynecology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania; Department of Obstetrics and Gynecology, Drexel University College of Medicine, Philadelphia, Pennsylvania; Department of Neurology, Alfred I. duPont Hospital for Children, Wilmington, Delaware; and Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
Address reprint requests to: Dawnette Lewis, MD, MPH, Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology North Shore–Long Island Jewish Health System, North Shore University Hospital, 300 Community Drive, Manhasset, NY 11030; e-mail: DAML2{at}aol.com.
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ABSTRACT |
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METHODS: This is a retrospective cohort study of patients with myelomeningocele followed at the Spinal Dysfunction Program at Alfred I. duPont Hospital for Children in Wilmington, Delaware. Medical 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 function. Ambulation status (independent ambulation, ambulant with assistance, or wheelchair-bound) at 2 and 10 years was compared with those delivered by elective cesarean versus those delivered after trial of labor.
RESULTS: Of the 106 patients with myelomeningocele that were identified, 87 (82%) had all the data required for this review. There were 44 patients in the elective cesarean group and 43 in the trial of labor group. There was no significant difference in gestational age at delivery or birthweight between the groups. There was statistical difference between the 2 groups when anatomical, initial, and current motor levels were compared. Compared with the elective cesarean group, patients in the trial of labor group were more likely to be ambulatory at 2 years (independently ambulant 7% versus 28%, ambulant with assistance 63% versus 65%, or wheelchair-bound 30% versus 7%, P = .003) and at 10 years (independently ambulant 5% versus 21%, ambulant with assistance 30% versus 54%, or wheelchair-bound 65% versus 25%, P < .001). However, when logistic regression analysis was used to control for motor level of myelomeningocele, no significant association was observed in ambulatory status at ages 2 and 10 years between infants delivered by elective cesarean or after trial of labor.
CONCLUSION: Elective cesarean delivery, when compared with delivery after trial of labor, was not associated with better motor function or ambulation status in myelomeningocele patients.
LEVEL OF EVIDENCE: II-2
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.
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MATERIALS AND METHODS |
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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, 
= .05 and ß = .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 
2 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).
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RESULTS |
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). 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).
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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.
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DISCUSSION |
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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 ( = .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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Footnotes |
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The authors thank Inna Chervoneva, MSc, Senior Biostatistician, Biostatistics Section, Department of Clinical Pharmacology, Thomas Jefferson University, Philadelphia, Pennsylvania, for assistance with statistical analysis, and Babu Cheku, MD, MPH, Division of Research in Reproductive Health, Department of Obstetrics and Gynecology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, for assistance with the power analysis and sample size calculations.
doi:10.1097/01.AOG.0000113624.94710.ce
Received June 20, 2003. Received in revised form October 27, 2003. Accepted November 13, 2003.
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