Mary E. Dabrowiak

A Randomized Trial of Prenatal versus Postnatal Repair of Myelomeningocele

BACKGROUND Prenatal repair of myelomeningocele, the most common form of spina bifida, may result in better neurologic function than repair deferred until after delivery. We compared outcomes of in utero repair with standard postnatal repair. METHODS We randomly assigned eligible women to undergo either prenatal surgery before 26 weeks of gestation or standard postnatal repair. One primary outcome was a composite of fetal or neonatal death or the need for placement of a cerebrospinal fluid shunt by the age of 12 months. Another primary outcome at 30 months was a composite of mental development and motor function. RESULTS The trial was stopped for efficacy of prenatal surgery after the recruitment of 183 of a planned 200 patients. This report is based on results in 158 patients whose children were evaluated at 12 months. The first primary outcome occurred in 68% of the infants in the prenatal-surgery group and in 98% of those in the postnatal-surgery group (relative risk, 0.70; 97.7% confidence interval [CI], 0.58 to 0.84; P<0.001). Actual rates of shunt placement were 40% in the prenatal-surgery group and 82% in the postnatal-surgery group (relative risk, 0.48; 97.7% CI, 0.36 to 0.64; P<0.001). Prenatal surgery also resulted in improvement in the composite score for mental development and motor function at 30 months (P=0.007) and in improvement in several secondary outcomes, including hindbrain herniation by 12 months and ambulation by 30 months. However, prenatal surgery was associated with an increased risk of preterm delivery and uterine dehiscence at delivery. CONCLUSIONS Prenatal surgery for myelomeningocele reduced the need for shunting and improved motor outcomes at 30 months but was associated with maternal and fetal risks. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00060606.).

Bladder Function After Fetal Surgery for Myelomeningocele

BACKGROUND: A substudy of the Management of Myelomeningocele Study evaluating urological outcomes was conducted. METHODS: Pregnant women diagnosed with fetal myelomeningocele were randomly assigned to either prenatal or standard postnatal surgical repair. The substudy included patients randomly assigned after April 18, 2005. The primary outcome was defined in their children as death or the need for clean intermittent catheterization (CIC) by 30 months of age characterized by prespecified criteria. Secondary outcomes included bladder and kidney abnormalities observed by urodynamics and renal/bladder ultrasound at 12 and 30 months, which were analyzed as repeated measures. RESULTS: Of the 115 women enrolled in the substudy, the primary outcome occurred in 52% of children in the prenatal surgery group and 66% in the postnatal surgery group (relative risk [RR]: 0.78; 95% confidence interval [CI]: 0.57–1.07). Actual rates of CIC use were 38% and 51% in the prenatal and postnatal surgery groups, respectively (RR: 0.74; 95% CI: 0.48–1.12). Prenatal surgery resulted in less trabeculation (RR: 0.39; 95% CI: 0.19–0.79) and fewer cases of open bladder neck on urodynamics (RR: 0.61; 95% CI: 0.40–0.92) after adjustment by child’s gender and lesion level. The difference in trabeculation was confirmed by ultrasound. CONCLUSIONS: Prenatal surgery did not significantly reduce the need for CIC by 30 months of age but was associated with less bladder trabeculation and open bladder neck. The implications of these findings are unclear now, but support the need for long-term urologic follow-up of patients with myelomeningocele regardless of type of surgical repair.

Upper level of the spina bifida defect: how good are we?

To assess the accuracy of obstetric sonography in determining the upper level of myelomeningocele lesions.

The Management of Myelomeningocele Study: Obstetrical Outcomes and Risk Factors for Obstetrical Complications Following Prenatal Surgery

BACKGROUND The Management of Myelomeningocele Study was a multicenter randomized trial to compare prenatal and standard postnatal closure of myelomeningocele. The trial was stopped early at recommendation of the data and safety monitoring committee and outcome data for 158 of the 183 randomized women published. OBJECTIVE In this report, pregnancy outcomes for the complete trial cohort are presented. We also sought to analyze risk factors for adverse pregnancy outcome among those women who underwent prenatal myelomeningocele repair. STUDY DESIGN Pregnancy outcomes were compared between the 2 surgery groups. For women who underwent prenatal surgery, antecedent demographic, surgical, and pregnancy complication risk factors were evaluated for the following outcomes: premature spontaneous membrane rupture ≤34 weeks 0 days (preterm premature rupture of membranes), spontaneous membrane rupture at any gestational age, preterm delivery at ≤34 weeks 0 days, nonintact hysterotomy (minimal uterine wall tissue between fetal membranes and uterine serosa, or partial or complete dehiscence at delivery), and chorioamniotic membrane separation. Risk factors were evaluated using χ2 and Wilcoxon tests and multivariable logistic regression. RESULTS A total of 183 women were randomized: 91 to prenatal and 92 to postnatal surgery groups. Analysis of the complete cohort confirmed initial findings: that prenatal surgery was associated with an increased risk for membrane separation, oligohydramnios, spontaneous membrane rupture, spontaneous onset of labor, and earlier gestational age at birth. In multivariable logistic regression of the prenatal surgery group adjusting for clinical center, earlier gestational age at surgery and chorioamniotic membrane separation were associated with increased risk of spontaneous membrane rupture (odds ratio, 1.49; 95% confidence interval, 1.01-2.22; and odds ratio, 2.96, 95% confidence interval, 1.05-8.35, respectively). Oligohydramnios was associated with an increased risk of subsequent preterm delivery (odds ratio, 9.21; 95% confidence interval, 2.19-38.78). Nulliparity was a risk factor for nonintact hysterotomy (odds ratio, 3.68; 95% confidence interval, 1.35-10.05). CONCLUSION Despite the confirmed benefits of prenatal surgery, considerable maternal and fetal risk exists compared with postnatal repair. Early gestational age at surgery and development of chorioamniotic membrane separation are risk factors for ruptured membranes. Oligohydramnios is a risk factor for preterm delivery and nulliparity is a risk factor for nonintact hysterotomy at delivery.

Reducing perinatal complications and preterm delivery for patients undergoing in utero closure of fetal myelomeningocele: further modifications to the multidisciplinary surgical technique

UNLABELLED OBJECT.: As more pediatric neurosurgeons become involved with fetal myelomeningocele closure efforts, examining refined techniques in the overall surgical approach that could maximize beneficial outcomes becomes critical. The authors compared outcomes for patients who had undergone a modified technique with those for patients who had undergone fetal repair as part of the earlier Management of Myelomeningocele Study (MOMS). METHODS Demographic and outcomes data were collected for a series of 43 delivered patients who had undergone in utero myelomeningocele closure at the Fetal Center at Vanderbilt from March 2011 through January 2013 (the study cohort) and were compared with data for 78 patients who had undergone fetal repair as part of MOMS (the MOMS cohort). For the study cohort, no uterine trocar was used, and uterine entry, manipulation, and closure were modified to minimize separation of the amniotic membrane. Weekly ultrasound reports were obtained from primary maternal-fetal medicine providers and reviewed. A test for normality revealed that distribution for the study cohort was normal; therefore, parametric statistics were used for comparisons. RESULTS The incidence of premature rupture of membranes (22% vs 46%, p = 0.011) and chorioamnion separation (0% vs 26%, p < 0.001) were lower for the study cohort than for the MOMS cohort. Incidence of oligohydramnios did not differ between the cohorts. The mean (± SD) gestational age of 34.4 (± 6.6) weeks for the study cohort was similar to that for the MOMS cohort (34.1 ± 3.1 weeks). However, the proportion of infants born at term (37 weeks or greater) was significantly higher for the study cohort (16 of 41; 39%) than for the MOMS cohort (16 of 78; 21%) (p = 0.030). Compared with 10 (13%) of 78 patients in the MOMS cohort, only 2 (4%) of 41 infants in the study cohort were delivered earlier than 30 weeks of gestation (p = 0.084, approaching significance). For the study cohort, 2 fetal deaths were attributed to the intervention, and both were believed to be associated with placental disruption; one of these mothers had previously unidentified thrombophilia. Mortality rates did not statistically differ between the cohorts. CONCLUSIONS These early results suggest that careful attention to uterine entry, manipulation, and closure by the surgical team can result in a decreased rate of premature rupture of membranes and chorioamnion separation and can reduce early preterm delivery. Although these results are promising, their confirmation will require further study of a larger series of patients.

Upper level of the spina bifida defect: How good are we?

OBJECTIVE To assess the accuracy of obstetric sonography in determining the upper level of myelomeningocele lesions. METHODS This was a retrospective study of 171 consecutive cases of spina bifida repaired in utero. The upper level of the lesion as determined by obstetric sonography was assigned by community physicians prior to referral in the second trimester and by the authors at Vanderbilt University Medical Center during preoperative evaluation. One hundred and eleven cases had levels established by plane-film X-ray or magnetic resonance imaging after delivery and this was regarded as the gold standard. RESULTS Of the 171 community examinations, only 29% identified a specific upper level of the lesion; our corresponding examinations specified the lesion level in all cases. Of the 111 cases that had upper levels of the lesion established by post-delivery imaging, corresponding levels were available for comparison from 35 of the community examinations and from 111 of the examinations performed at Vanderbilt. All three assigned levels were available for comparison in 35 cases. In 26% of cases, community-assigned levels agreed exactly with post-delivery levels, while 66% agreed within one level and 80% agreed within two levels. In 38% of cases, levels assigned at Vanderbilt agreed exactly with post-delivery levels, while 78% agreed within one level and 96% agreed within two levels. Upper levels of the lesion assigned at Vanderbilt were significantly more accurate overall compared with those assigned by community physicians (signed rank test [paired comparison], P = 0.048). However, comparison of lesion levels assigned at Vanderbilt in the first 50 vs. the last 61 cases revealed a significant learning effect (Fishers exact test, P = 0.03). When comparison of lesion levels assigned by community physicians was restricted to the first 50 cases at Vanderbilt, accuracy was similar (n = 13; t-test, P = 0.16; rank sum test, 0.31). CONCLUSIONS Community physicians were successful in assigning the upper level of the spina bifida lesion only 29% of the time. When successful, the accuracy of these determinations was similar to that of the authors at Vanderbilt. A significant learning effect was demonstrated by improved accuracy over time at Vanderbilt. A concerted continuing medical education effort is indicated to improve the imaging skills of physicians in the accurate diagnosis of the severity of spina bifida in fetuses.