Comparison of two fetoscopic open neural tube defect repair techniques: single- vs three-layer closure

The first experience with 16 open microsurgical fetal surgeries for myelomeningocele in Germany

INTRODUCTION

Fetal surgery for spina bifida aperta has achieved great advancement in last decade offering three possible methods for surgical repair. Open fetal microsurgical repair still remains the gold standard considering long-term results available. Since 2016, we established a program offering this modality of treatment in Germany.

PATIENTS AND METHODS

All patients who underwent interdisciplinary prenatal evaluation following a standardized protocol between June 2016-June 2024. Sacral lesions were excluded. The surgical technique and protocol used were similar to that described in Management Of Myelomeningocele Study (MOMS).

RESULTS

Sixteen patients underwent surgery for spina bifida aperta without fetal nor maternal deaths. Microsurgical fetal repair was performed between 24th and 25th week of gestation age (GA) (Mean: 24 + 5 weeks GA). Lesion levels were mainly lumbosacral (n = 15) and one thoracolumbar (n = 1). Repair was successful in all 16 cases and with reversible hindbrain herniation at time of birth in 13/16 patients (81.3 %). Average time of delivery was 33 + 5 weeks GA, with 8 preterm deliveries occurring before 37 weeks GA; average birth weight was 2193 g. Maternal complications included 2 patients with uterine scar thinning. Hydrocephalus management was needed in 5/16 patiens (31.25 %) via ventriculo-peritoneal shunting.

CONCLUSION

Open fetal repair of spina bifida aperta in selected fetuses is safe and offers the unborn child a better quality of life but does not cure the disease and is not without risks or complications. Collaboration within the pediatric community is recommended to compile data in a common registry to develop standardized treatment and follow-up protocols.

Fetoscopic Myelomeningocele (MMC) Repair: Evolution of the Technique and a Call for Standardization

Fetal surgery has made significant strides over the past 40 years, facilitated by advances in technology and imaging modalities enabling the diagnosis and treatment of congenital anomalies in utero. The Management of Myelomeningocele Study (MOMS), a multicenter randomized controlled trial, established open fetal myelomeningocele (MMC) repair as the gold standard for improving neurological outcomes compared to postnatal repair. However, this approach is associated with increased maternal complications and preterm birth due to hysterotomy, prompting the exploration of minimally invasive alternatives. Due to the lack of an existing randomized control trial with fetoscopic MMC repair and variations in technique (percutaneous versus laparotomy/transuterine access, different trocar configurations, closure methods, and patch applications) among different fetal centers, more studies are needed to optimize this approach as an alternative to the standard of care. This paper proposes to assess the basics tenets of open fetal MMC repair and to establish guiding principles for a fetoscopic approach that could prove to be equivalent or superior to open fetal MMC repair in maternal and fetal outcomes and lead to clinical implementation.

Implementation of in utero laparotomy-assisted fetoscopic spina bifida repair in two centers in Latin America: rationale for this approach in this region

Background

Spina bifida (SB) is a severe congenital malformation that affects approximately 150,000 infants annually, predominantly in low- and middle-income countries, leading to significant morbidity and lifelong disabilities. In Latin America, the birth prevalence of SB is notably high, often exacerbated by limited healthcare resources and poor access to advanced medical care. The implementation of laparotomy-assisted fetoscopic in-utero SB repair programs in Latin America targets reducing prematurity rates and enabling vaginal births while preserving the benefits of decreased need for hydrocephalus treatment and improved mobility in children.

Objective

This study evaluated the safety, efficacy, and outcomes of laparotomy-assisted fetoscopic in-utero SB repair in Latin America compared to traditional open-hysterotomy methods.

Study design

This retrospective cohort study included 39 cases of laparotomy-assisted fetoscopic in-utero SB repair, with 14 cases from Mexico (2017-2021) and 25 cases from Colombia (2019-2024). These cases were compared to 78 cases from the MOMs trial and 314 from other Latin American centers using traditional open-hysterotomy methods. Statistical analyses included the Student's t-test, Kruskal-Wallis test, and Pearson's chi-square test.

Results

The gestational age (GA) at the time of surgery was significantly higher in fetoscopic centers (26±1.27 weeks) compared to the MOMs trial (23.6±1.42 weeks) and traditional hysterotomy methods (25.4±1 weeks) (P<.001). Mean GA at delivery was significantly earlier in the hysterotomy-based groups than in our fetoscopic group (MOMs: 34.1 [± 3.1] vs open-repair centers in LATAM: 34 [±3002] vs Fetoscopic: 35.3 [± 3.79] weeks; P values=.14 and 0004, respectively). Moreover, and the fetoscopic repair group exhibited a significantly lower rate of spontaneous preterm births (<34 weeks) at 15.8%, compared to 46.2% in the MOMs trial group and 49% in the other Latin American centers using traditional open-hysterotomy methods (P=.004 and .001, respectively). Additionally, the fetoscopic group had higher birthweights (2618±738g) and a lower cesarean delivery rate (65.8%) compared to the other groups (P<.001). Hydrocephalus treatment requirements at 12 months were similar across all groups. No maternal deaths or other outcomes such as pulmonary edema or need for maternal transfusion were noted in the fetoscopic SB repair group.

Conclusion

The laparotomy-assisted fetoscopic SB repair offers a feasible and safer alternative to traditional hysterotomy-based techniques in Latin America. This approach significantly reduces the rates of prematurity and cesarean deliveries, facilitating vaginal births and minimizing maternal morbidity. These findings support the broader adoption of fetoscopic SB repair in regions with a high prevalence of SB and suboptimal perinatal outcomes, underscoring its advantages over hysterotomy-based approaches.

"This is how we do it" Maternal and fetal anesthetic management for fetoscopic myelomeningocele repairs: the Texas Children's Fetal Center protocol

Prenatal repair of myelomeningocele (MMC) is associated with lower rates of hydrocephalus requiring ventriculoperitoneal shunt and improved motor function when compared with postnatal repair. Efforts aiming to develop less invasive surgical techniques to decrease the risk for the pregnant patient while achieving similar benefits for the fetus have led to the implementation of fetoscopic surgical techniques. While no ideal anesthetic technique for fetoscopic MMC repair has been demonstrated, we present our anesthetic approach for these repairs, including considerations for both the pregnant patient and the fetus. We emphasize the importance of the preoperative consultation to optimize any medical conditions and to set expectations for the perioperative course. Our preferred anesthetic technique for the pregnant patient includes general anesthesia with an epidural for postoperative analgesia. Intraoperative anesthetic considerations for patients undergoing fetoscopic surgery include tocolysis, meticulous control of hemodynamics, judicious fluid administration, and maternal temperature regulation. We also avoid long-acting neuromuscular blocking agents due to significant weakness observed when given in combination with magnesium sulfate. While the maternal anesthetic crosses the placenta, direct administration of anesthesia to the fetus is required to reliably blunt the stress response. Additional considerations for the fetus include monitoring, fetal resuscitation strategies, and the theoretical risk of anesthetic neurotoxicity. Postoperatively, we use a multi-modal, opioid sparing regimen for analgesia. As advances in fetal surgery aiming to minimize risk to the pregnant patient alter the surgical approach, maternal-fetal anesthesiologists must adapt and incorporate the unique considerations of fetoscopy into their anesthetic management.

The Intrauterine Treatment of Open Spinal Dysraphism

BACKGROUND

Open spinal dysraphism is a congenital malformation that causes major morbidity. Its consequences include sensory and motor impairment as well as bladder- and bowel dysfunction. It is often also associated with prenatal ventriculomegaly, which, in turn, necessitates postnatal treatment with a ventriculoperitoneal shunt in approximately 80% of cases. Prenatal therapy with coverage of neural tube defect can reduce the shunt rate and preserve motor function. In this review, we describe the different surgical procedures and their outcomes.

METHODS

This review is based on publications that were retrieved by a selective literature search in the MEDLINE, Web of Science, EMBASE, Scopus, and Cochrane databases, employing pertinent keywords. Studies of all types (except case reports) that were published in English or German in the period 2010-2024 were included.

RESULTS

The randomized, controlled MOMS trial showed that intrauterine surgery for defect closure resulted in less progressive neural tissue damage than postnatal surgery and reduced the need for shunting by approximately half (40% vs. 82%). Since the publication of these results, various prenatal surgical procedures have been established, including hysterotomy-assisted, percutaneous fetoscopic, and laparotomy-assisted fetoscopic closure. The individual surgical methods yield comparable results in terms of motor function and shunt rate. A problem with these procedures is that they increase the likelihood of preterm birth, to an extent that varies from one type of procedure to another.

CONCLUSION

Prenatal surgery improves motor function and reduces the shunt rate but long-term outcomes beyond adolescence are still lacking. Transparent and interdisciplinary counseling is essential in prenatal communication to inform parents not only about the potential benefits of this treatment, but also about its limitations and risks.

A new ex vivo model system to analyze factors affecting the integrity of fetal membranes in fetoscopic surgery

We developed an ex vivo model system to analyze the influence of relevant environmental and mechanical factors potentially affecting the integrity of fetal membranes during fetoscopic surgery. The set-up exposes amniochorion membranes to insufflation at predefined levels of gas pressure, flow, humidity, and temperature. Change in fetal membranes stiffness is quantified during the phase mimicking surgery through measurement of membranes' strain in response to cyclic overpressure. The trocar induced perforation creates a mechanical weakness whose stability is assessed by increasing the insufflation pressure until membrane rupture. Damage of the epithelial cells lining the amnion is assessed through live-dead staining. Initial experiments demonstrated the functionality of the new apparatus and the feasibility of the proposed protocols. Fetal membranes exposed to air with low humidity for approximately 1 h demonstrated significant embrittlement, while their mechanical integrity was maintained in case of gas insufflation at high humidity (air as well as CO2). Under dry circumstances, there was a significant rate of epithelial cell death. Separation of amnion and chorion in the region of the trocar site was visible in all experiments. This new model is a versatile platform for analyzing the mechanical, histological, and biological implications of fetoscopic surgery on fetal membranes.

The effect of using synthetic vs. biological dural substitutes during prenatal and postnatal repair of spina bifida on spinal cord tethering-a review of literature

Spina bifida is a congenital neural tube closure defect, with myelomeningocele being the most clinically significant open neural tube defect occurring in one in 1000 births worldwide as reported by Phillips LA et al. (Curr Probl Pediatr Adolesc Health Care 47(7):173-177, 2017) and Zerah M and Kulkarni AV (Handb Clin Neurol 112:975-991, 2013). With advances in fetal surgery, this condition can be corrected in utero. Despite such precision surgery, many complications may still arise, with consequent spinal cord tethering being a major one. When the roots of the spinal cord adhere to the spinal canal instead of floating freely within the dural sleeve within the canal, it is termed as "tethering" as discussed by Martínez-Lage JF et al. (Neurocirugia (Astur) 18(4):312-319, 2007). Tethering has a variety of complications, which are best avoided by analyzing the outcomes of the different dural substitutes and improving surgical techniques. This literature review evaluates the use of different dural substitutes in fetal and postnatal surgery, with their effects on spinal cord tethering. Finding a significant difference in spinal cord adherence outcomes between these two groups can help one introspect on the impact of ideal surgical techniques to be implemented, thus reducing subsequent tethering and other future surgical interventions.

Delivery Room Management of Infants with Surgical Conditions

Delivery room resuscitation of infants with surgical conditions can be complex and depends on an experienced and cohesive multidisciplinary team whose performance is more important than that of any individual team member. Existing resuscitation algorithms were not developed for infants with congenital anomalies, and delivery room resuscitation is largely dictated by expert opinion extrapolating physiologic expectations from infants without anomalies. As prenatal diagnosis rates improve, there is an increased ability to plan for the unique delivery room needs of infants with surgical conditions. In this review, we share expert opinion, including our center's delivery room management for neonatal noncardiac surgical conditions, and highlight knowledge gaps and the need for further studies and evidence-based practice to be incorporated into the delivery room care of infants with surgical conditions. Future research in this area is essential to move from an expert-based approach to a data-driven approach to improve and individualize delivery room resuscitation of infants with surgical conditions.

Anchoring device to prevent membrane detachment and preterm prelabor rupture of membranes after fetal intervention

OBJECTIVE

To assess the feasibility of using a novel device designed for minimally invasive suturing to anchor fetal membranes to the uterine wall and to close surgical defects after fetoscopy.

METHODS

We tested the WestStitch™ suturing device both ex vivo and in vivo. In the ex-vivo studies, 12-Fr trocar defects were created with a fetoscope in five specimens of human uterine tissue with fetal membranes attached. Specimens were examined for integrity of the anchoring stitch. For the in-vivo studies, trocar defects were created in the two uterine horns of three pregnant ewes, each carrying twins at approximately 79-90 days' gestation. One trocar defect in each ewe was repaired using the suture device, and the other was left unrepaired as a control. The repair sites were examined for membrane-anchoring integrity when the defect was created and at delivery.

RESULTS

Fetal membranes were anchored successfully to the uterine myometrium using the suture-delivery device in all five experiments performed ex vivo. The in-vivo experiments also revealed successful membrane anchoring compared with controls, both at the time of device deployment and 1-9 weeks after the procedure.

CONCLUSIONS

We successfully anchored amniotic membranes to the underlying myometrium using a suturing device, both ex vivo and in vivo. Further studies are needed to evaluate the efficacy of the device and to determine whether it can successfully anchor fetal membranes percutaneously in human patients. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Ambulation after in-utero fetoscopic or open neural tube defect repair: predictors for ambulation at 30 months

OBJECTIVES

To compare the ambulatory status of a cohort of children who had undergone prenatal repair of an open neural tube defect (ONTD) using one of two different methods (fetoscopic or open hysterotomy) with that of a cohort who had undergone postnatal repair, and to identify the best predictors of ambulation at 30 months of age.

METHODS

This was a retrospective review of a cohort of children who underwent ONTD repair either prenatally (n = 110), by fetoscopic surgery (n = 73) or open hysterotomy surgery (n = 37), or postnatally (n = 51), in a single tertiary hospital between November 2011 and May 2023. The cohort comprised a consecutive sample of cases who had undergone ONTD repair in-utero following Management of Myelomeningocele Study (MOMS) trial criteria and cases who had undergone postnatal repair, meeting the same criteria, which were also followed up after birth at the same institution. Motor function assessment by ultrasound was recorded at referral, 6 weeks after prenatal repair, or after referral in postnatally repaired cases, and at the last ultrasound scan before delivery. Clinical examinations to assess motor function at birth and at 12 months were retrieved from records. Intact motor function was defined as first sacral myotome (S1) motor function. Ambulatory status data at each follow-up visit were collected. The proportion of children who were able to walk independently after 30 months of age was compared between those who had undergone fetoscopic vs open prenatal surgery and between prenatal (by either fetoscopic or open surgery) and postnatal ONTD repair. Logistic regression analyses were performed to identify predictors for independent ambulation.

RESULTS

After 30 months, the proportion of infants who were able to walk independently was higher in prenatally vs postnatally repaired cases (51.8% vs 15.7%, P < 0.01), and there was no difference between those with fetoscopic (52.1%) vs open (51.4%) prenatal repair (P = 0.66). In the prenatally repaired group, having intact motor function at 12 months (adjusted odds ratio (aOR), 9.14 (95% CI, 2.64-31.63), P < 0.01) and at birth (aOR, 4.50 (95% CI, 1.21-16.80), P = 0.02) were significant predictors of independent walking at 30 months; an anatomical level of lesion below L2 at referral (aOR, 1.83 (95% CI, 1.30-2.58), P = 0.01) and female gender (aOR, 3.51 (95% CI, 1.43-8.61), P < 0.01) were also predictive for this outcome.

CONCLUSIONS

Prenatally repaired cases of ONTD have a better chance of being able to walk independently at 30 months than do those who undergo postnatal repair. In patients with prenatally repaired ONTD, ambulatory status at 30 months can be predicted by observing a low lesion level at referral (below L2) and intact motor function postnatally. These results have implications for parental counseling and planning for supportive therapy in pregnancies affected by ONTD. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal surgery for open neural tube defect with severe ventriculomegaly

OBJECTIVE

Prenatal open neural tube defect (ONTD) repair is performed to decrease the risk of needing treatment for hydrocephalus after birth and to preserve motor function. Some centers may not consider patients to be candidates for surgery if severe ventriculomegaly is present and there is no expected benefit in risk for hydrocephalus treatment. This study sought to compare the postnatal outcome of fetuses with ONTD and severe ventriculomegaly (ventricular width ≥ 15 mm) that underwent prenatal repair with the outcome of fetuses with severe ventriculomegaly that underwent postnatal repair and fetuses without severe ventriculomegaly (< 15 mm) that underwent prenatal repair.

METHODS

This was a retrospective study of fetuses with ONTD that underwent prenatal or postnatal repair between 2012 and 2021 at a single institution. The cohort was divided into two groups based on preoperative fetal ventricular size: those with severe ventriculomegaly (ventricular width ≥ 15 mm) and those without severe ventriculomegaly (< 15 mm). Fetal ventricular size was measured by magnetic resonance imaging before surgery using the standardized approach and the mean size of the left and right ventricles was used for analysis. Motor function of the lower extremities was assessed at the time of referral by ultrasound and if flexion-extension movements of the ankle were seen it was considered as preserved S1 motor function. Postnatal outcomes, including motor function of the lower extremities at birth and the need for a diversion procedure for hydrocephalus treatment during the first year after birth, were collected and compared between groups. Multivariate regression analysis was used to adjust for potential confounders.

RESULTS

In this study, 154 patients were included: 145 underwent fetal surgery (101 fetoscopic and 44 open hysterotomy) and nine with severe ventriculomegaly underwent postnatal repair. Among the 145 patients who underwent fetal surgery, 22 presented with severe ventriculomegaly. Fetuses with severe ventriculomegaly at referral that underwent prenatal repair were significantly more likely to need hydrocephalus treatment by 12 months after birth than those without severe ventriculomegaly (61.9% vs 28.9%, P < 0.01). However, motor function assessment at birth was similar between both prenatal repair groups (odds ratio, 0.92 (95% CI, 0.33-2.59), P = 0.88), adjusted for the anatomical level of the lesion. The prenatal repair group with severe ventriculomegaly had better preserved motor function at birth compared to the postnatal repair group with severe ventriculomegaly (median level, S1 vs L3, P < 0.01; proportion with S1 motor function, 68.2% vs 11.1%, P < 0.01). Fetuses with severe ventriculomegaly that underwent prenatal repair had an 18.9 (95% CI, 1.2-290.1)-times higher chance of having intact motor function at birth, adjusted for ethnicity, presence of club foot at referral and gestational age at delivery, compared with the postnatal repair group. There was no significant difference in the need for hydrocephalus treatment in the first year after birth between prenatal and postnatal repair groups with severe ventriculomegaly (61.9% vs 87.5%, P = 0.18).

CONCLUSIONS

Although fetuses with ONTD and severe ventriculomegaly do not seem to benefit from fetal surgery in terms of postnatal hydrocephalus treatment, there is an increased chance of preserved motor function at birth. Results from this study highlight the benefit of prenatal ONTD repair for cases with severe ventriculomegaly at referral to preserve motor function. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

The impact of a biocellulose-based repair of fetal open spina bifida on the need to untether the cord: is it time to unify techniques for prenatal repair?

OBJECTIVE

To report the need for cord untethering after prenatal repair of open spina bifida using a unique biocellulose-based technique performed at a later gestational age.

METHODS

An observational cohort study was conducted to determine the incidence of tethered cord syndrome. Between May 2013 and May 2022, we performed 172 procedures using the percutaneous fetoscopic approach in fetuses at 26-28 weeks of gestation. After placode dissection, a biocellulose patch was placed to cover the placode, a myofascial flap (when possible) was dissected, and the skin was closed. Owing to death or loss to follow-up, 23 cases were excluded. Cord tethering syndrome was defined as symptoms of medullary stretching, and the infants were evaluated and operated on by local neurosurgeons after an magnetic resonance imaging examination. Infants over 30-month had ambulation and neurodevelopment evaluations (PEDI scale).

RESULTS

Among 172 cases operated at a median gestational age of 26.7 weeks and delivered at 33.2 weeks, 149 cases were available for postnatal follow-up, and cord untethering was needed in 4.4% of cases (6/136; excluding 13 cases younger than 12 months). Cerebrospinal fluid diversion and bladder catheterization were needed in 38% and 36% of cases, respectively. Of the 78 cases evaluated at 30 months, 49% were ambulating independently, and 94% had normal social function.

CONCLUSION

The biocellulose-based technique was associated with a low rate of cord tethering, wich may be attributed to the lack of the duramater suture during prenatal repair, the formation of a neoduramater and/or later gestational age of surgery.

Perforation of cavum septi pellucidi in open spina bifida and need for hydrocephalus treatment by 1 year of age

OBJECTIVE

In-utero repair of an open neural tube defect (ONTD) reduces the risk of developing severe hydrocephalus postnatally. Perforation of the cavum septi pellucidi (CSP) may reflect increased intraventricular pressure in the fetal brain. We sought to evaluate the association of perforated CSP visualized on fetal imaging before and/or after in-utero ONTD repair with the eventual need for hydrocephalus treatment by 1 year of age.

METHODS

This was a retrospective cohort study of consecutive patients who underwent laparotomy-assisted fetoscopic ONTD repair between 2014 and 2021 at a single center. Eligibility criteria for surgery were based on those of the Management of Myelomeningocele Study (MOMS), although a maternal prepregnancy body mass index of up to 40 kg/m2 was allowed. Fetal brain imaging was performed with ultrasound and magnetic resonance imaging (MRI) at referral and 6 weeks postoperatively. Stored ultrasound and MRI scans were reviewed retrospectively to assess CSP integrity. Medical records were reviewed to determine whether hydrocephalus treatment was needed within 1 year of age. Parametric and non-parametric tests were used as appropriate to compare outcomes between cases with perforated CSP and those with intact CSP as determined on ultrasound at referral. Logistic regression analysis was performed to assess the predictive performance of various imaging markers for the need for hydrocephalus treatment.

RESULTS

A total of 110 patients were included. Perforated CSP was identified in 20.6% and 22.6% of cases on preoperative ultrasound and MRI, respectively, and in 26.6% and 24.2% on postoperative ultrasound and MRI, respectively. Ventricular size increased between referral and after surgery (median, 11.00 (range, 5.89-21.45) mm vs 16.00 (range, 7.00-43.5) mm; P < 0.01), as did the proportion of cases with severe ventriculomegaly (ventricular width ≥ 15 mm) (12.7% vs 57.8%; P < 0.01). Complete CSP evaluation was achieved on preoperative ultrasound in 107 cases, of which 22 had a perforated CSP and 85 had an intact CSP. The perforated-CSP group presented with larger ventricles (mean, 14.32 ± 3.45 mm vs 10.37 ± 2.37 mm; P < 0.01) and a higher rate of severe ventriculomegaly (40.9% vs 5.9%; P < 0.01) compared to those with an intact CSP. The same trends were observed at 6 weeks postoperatively for mean ventricular size (median, 21.0 (range, 13.0-43.5) mm vs 14.3 (range, 7.0-29.0) mm; P < 0.01) and severe ventriculomegaly (95.0% vs 46.8%; P < 0.01). Cases with a perforated CSP at referral had a lower rate of hindbrain herniation (HBH) reversal postoperatively (65.0% vs 88.6%; P = 0.01) and were more likely to require treatment for hydrocephalus (89.5% vs 22.7%; P < 0.01). The strongest predictor of the need for hydrocephalus treatment within 1 year of age was lack of HBH reversal on MRI (odds ratio (OR), 36.20 (95% CI, 5.96-219.12); P < 0.01) followed by perforated CSP on ultrasound at referral (OR, 23.40 (95% CI, 5.42-100.98); P < 0.01) and by perforated CSP at 6-week postoperative ultrasound (OR, 19.48 (95% CI, 5.68-66.68); P < 0.01).

CONCLUSIONS

The detection of a perforated CSP in fetuses with ONTD can reliably identify those cases at highest risk for needing hydrocephalus treatment by 1 year of age. Evaluation of this brain structure can improve counseling of families considering fetal surgery for ONTD, in order to set appropriate expectations about postnatal outcome. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Systematic classification and comparison of maternal and obstetrical complications following 2 different methods of fetal surgery for the repair of open neural tube defects

BACKGROUND

In utero repair of open neural tube defects using an open hysterotomy approach (hereafter referred to as "open") has been shown to reduce the need for ventriculoperitoneal shunting and to improve motor outcomes for affected infants. Laparotomy-assisted fetoscopic repair (hereafter referred to as "hybrid") is an alternative approach that may confer similar neurologic benefits while reducing the incidence of hysterotomy-related complications.

OBJECTIVE

This study aimed to analyze procedure-related maternal and fetal complications of in utero repair using the Clavien-Dindo classification, and to compare the outcomes of the hybrid and open approaches.

STUDY DESIGN

This was a retrospective cohort study conducted in a single center between September 2011 and July 2021. All patients who met the Management of Myelomeningocele Study criteria and who underwent either hybrid or open fetal surgery were included. Maternal complications were classified using a unique adaptation of the Clavien-Dindo scoring system, allowing the development of a comprehensive complication index score specific to fetal surgery. Primary fetal outcome was defined as gestational age at delivery and summarized according to the World Health Organization definitions of preterm delivery.

RESULTS

There were 146 fetuses with open neural tube defects who were eligible for, and underwent, in utero repair during the study period. Of these, 102 underwent hybrid fetoscopic repair and 44 underwent open hysterotomy repair. Gestational age at the time of surgery was higher in the hybrid group than in the open group (25.1 vs 24.8 weeks; P=.004). Maternal body mass index was lower in the hybrid than in the open group (25.4 vs 27.1 kg/m2; P=.02). The duration of hybrid fetoscopic surgery was significantly longer in the hybrid than in the open group (250 vs 164 minutes; P<.001). There was a significantly lower Clavien-Dindo Grade III complication rate (4.9% vs 43.2%; P<.001) and a significantly lower overall comprehensive maternal complication index (8.7 vs 22.6; P=.021) in the hybrid group than in the open group. Gestational age at delivery was significantly higher in the hybrid group than in the open group (38.1 vs 35.8 weeks; P<.001), and this finding persisted when gestational age at delivery was analyzed using the World Health Organization definitions of preterm delivery.

CONCLUSION

Use of our adaptation of the standardized Clavien-Dindo classification to assess the maternal complications associated with in utero open neural tube defect repair provides a new method for objectively assessing different fetal surgical approaches. It also provides a much-needed standardized tool to allow objective comparisons between methods, which can be used when counseling patients. The hybrid open neural tube defect repair was associated with lower rates of maternal adverse events , and later gestational age at delivery compared with the open approach.

Implication of chromosomal microarray analysis prior to in-utero repair of fetal open neural tube defect

OBJECTIVE

In-utero repair of open neural tube defects (ONTD) is an accepted treatment option with demonstrated superior outcome for eligible patients. While current guidelines recommend genetic testing by chromosomal microarray analysis (CMA) when a major congenital anomaly is detected prenatally, the requirement for an in-utero repair, based on the Management of Myelomeningocele Study (MOMS) criteria, is a normal karyotype. In this study, we aimed to evaluate if CMA should be recommended as a prerequisite for in-utero ONTD repair.

METHODS

This was a retrospective cohort study of pregnancies complicated by ONTD that underwent laparotomy-assisted fetoscopic repair or open-hysterotomy fetal surgery at a single tertiary center between September 2011 and July 2021. All patients met the MOMS eligibility criteria and had a normal karyotype. In a subset of the pregnancies (n = 77), CMA testing was also conducted. We reviewed the CMA results and divided the cohort into two groups according to whether clinically reportable copy-number variants (CNV) were detected (reportable-CNV group) or not (normal-CMA group). Surgical characteristics, complications, and maternal and early neonatal outcomes were compared between the two groups. The primary outcomes were fetal or neonatal death, hydrocephalus, motor function at 12 months of age and walking status at 30 months of age. Standard parametric and non-parametric statistical tests were employed as appropriate.

RESULTS

During the study period, 146 fetuses with ONTD were eligible for and underwent in-utero repair. CMA results were available for 77 (52.7%) patients. Of those, 65 (84%) had a normal CMA and 12 (16%) had a reportable CNV, two of which were classified as pathogenic. The first case with a pathogenic CNV was diagnosed with a 749-kb central 22q11.21 deletion spanning low-copy-repeat regions B-D of chromosome 22; the second case was diagnosed with a 1.3-Mb interstitial deletion at 1q21.1q21.2. Maternal demographics, clinical characteristics, operative data and postoperative complications were similar between those with normal CMA results and those with reportable CNVs. There were no significant differences in gestational age at delivery or any obstetric and early neonatal outcome between the study groups. Motor function at birth and at 12 months of age, and walking status at 30 months of age, were similar between the two groups.

CONCLUSIONS

Standard diagnostic testing with CMA should be offered when an ONTD is detected prenatally, as this approach has implications for counseling regarding prognosis and recurrence risk. Our results indicate that the presence of a clinically reportable CNV should not a priori affect eligibility for in-utero repair, as overall pregnancy outcome is similar in these cases to that of cases with normal CMA. Nevertheless, significant CMA results will require a case-by-case multidisciplinary discussion to evaluate eligibility. To generalize the conclusion of this single-center series, a larger, multicenter long-term study should be considered. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Abnormal prenatal brain development in Chiari II malformation

Introduction

The Chiari II is a relatively common birth defect that is associated with open spinal abnormalities and is characterized by caudal migration of the posterior fossa contents through the foramen magnum. The pathophysiology of Chiari II is not entirely known, and the neurobiological substrate beyond posterior fossa findings remains unexplored. We aimed to identify brain regions altered in Chiari II fetuses between 17 and 26 GW.

Methods

We used in vivo structural T2-weighted MRIs of 31 fetuses (6 controls and 25 cases with Chiari II).

Results

The results of our study indicated altered development of diencephalon and proliferative zones (ventricular and subventricular zones) in fetuses with a Chiari II malformation compared to controls. Specifically, fetuses with Chiari II showed significantly smaller volumes of the diencephalon and significantly larger volumes of lateral ventricles and proliferative zones.

Discussion

We conclude that regional brain development should be taken into consideration when evaluating prenatal brain development in fetuses with Chiari II.

Local host response of commercially available dural patches for fetal repair of spina bifida aperta in rabbit model

OBJECTIVE

Fetal surgery for spina bifida aperta (SBA) by open hysterotomy typically repairs anatomical native tissue in layers. Increasingly, fetoscopic repair is performed using a dural patch followed by skin closure. We studied the host response to selected commercially available patches currently being used in a fetal rabbit model for spina bifida repair.

METHODS

SBA was surgically induced at 23-24 days of gestation (term = 31 days). Fetal rabbits were assigned to unrepaired (SBA group), or immediate repair with Duragen™ or Durepair™. Non-operated littermates served as normal controls. At term, spinal cords underwent immunohistochemical staining including Nissl and glial fibrillary acidic protein. We hypothesized that spinal cord coverage with a dural patch and skin closure would preserve motor neuron density within the non-inferiority limit of 201.65 cells/mm² and reduce inflammation compared to unrepaired SBA fetuses.

RESULTS

Motor neuron density assessed by Nissl staining was conserved both by Duragen (n = 6, 89.5; 95% CI -158.3 to -20.6) and Durepair (n = 6, 37.0; 95% CI -132.6 to -58.5), whereas density of GFAP-positive cells to quantify inflammation was lower than in unrepaired SBA-fetuses (SBA 2366.0 ± 669.7 cells/mm² vs. Duragen 1274.0 ± 157.2 cells/mm² ; p = 0.0002, Durepair 1069.0 ± 270.7 cells/mm² ; p < 0.0001).

CONCLUSIONS

Covering the rabbit spinal cord with either Duragen or Durepair followed by skin closure preserves motor neuron density and reduces the inflammatory response.

Advances in Fetal Surgical Repair of Open Spina Bifida

Spina bifida remains a common congenital anomaly of the central nervous system despite national fortification of foods with folic acid, with a prevalence of 2-4 per 10,000 live births. Prenatal screening for the early detection of this condition provides patients with the opportunity to consider various management options during pregnancy. Prenatal repair of open spina bifida, traditionally performed by the open maternal-fetal surgical approach through hysterotomy, has been shown to improve outcomes for the child, including decreased need for cerebrospinal fluid diversion surgery and improved lower neuromotor function. However, the open maternal-fetal surgical approach is associated with relatively increased risk for the patient and the overall pregnancy, as well as future pregnancies. Recent advances in minimally invasive prenatal repair of open spina bifida through fetoscopy have shown similar benefits for the child but relatively improved outcomes for the pregnant patient and future childbearing.

A comparison of MRI appearance and surgical detethering rates between intrauterine and postnatal myelomeningocele closures: a single-center pilot matched cohort study

INTRODUCTION

Intrauterine myelomeningocele repair (IUMR) and postnatal myelomeningocele repair (PNMR) differ in terms of both setting and surgical technique. A simplified technique in IUMR, in which a dural onlay is used followed by skin closure, has been adopted at our institution. The goal of this study was to compare the rates of clinical tethering in IUMR and PNMR patients, as well as to evaluate the appearance on MRI.

METHODS

We conducted a retrospective review of 36 patients with MMC repaired at our institution, with 2:1 PNMR to IUMR matching based on lesion level. A pediatric neuroradiologist blinded to the clinical details reviewed the patients' lumbar spine MRIs for the distance from neural tissue to skin and the presence or absence of a syrinx. An EMR review was then done to evaluate for detethering procedures and need for CSF diversion.

RESULTS

Mean age at MRI was 4.0 years and mean age at last follow-up was 6.1 years, with no significant difference between the PNMR and IUMR groups. There was no significant difference between groups in the distance from neural tissue to skin (PNMR 13.5 mm vs IUMR 17.6 mm; p = 0.5). There was no difference in need for detethering operations between groups (PNMR 12.5% vs IUMR 16.7%; RR 0.75; CI 0.1-5.1).

CONCLUSIONS

There was no significant difference between postnatal- and intrauterine-repaired myelomeningocele on MRI or in need for detethering operations. These results imply that a more straightforward and time-efficient IUMR closure technique does not lead to an increased rate of tethering when compared to the multilayered PNMR.

Minimally Invasive Fetal Surgery and the Next Frontier

Most patients with congenital anomalies do not require prenatal intervention. Furthermore, many congenital anomalies requiring surgical intervention are treated adequately after birth. However, there is a subset of patients with congenital anomalies who will die before birth, shortly after birth, or experience severe postnatal complications without fetal surgery. Fetal surgery is unique in that an operation is performed on the fetus as well as the pregnant woman who does not receive any direct benefit from the surgery but rather lends herself to risks, such as hemorrhage, abruption, and preterm labor. The maternal risks involved with fetal surgery have limited the extent to which fetal interventions may be performed but have, in turn, led to technical innovations that have significantly advanced the field. This review will examine congenital abnormalities that can be treated with minimally invasive fetal surgery and introduce the next frontier of prenatal management of fetal surgical pathology.

Effect of preoperative low-normal cervical length on perinatal outcome after laparotomy-assisted fetoscopic spina bifida repair

OBJECTIVE

To determine if preoperative cervical length in the low-normal range increases the risk of adverse perinatal outcome in patients undergoing fetoscopic spina bifida repair.

METHODS

This was a retrospective cohort study of patients who underwent fetal spina bifida repair between September 2014 and May 2022 at a single center. Cervical length was measured on transvaginal ultrasound during the week before surgery. Eligibility for laparotomy-assisted fetoscopic spina bifida repair was as per the criteria of the Management of Myelomeningocele Study, although maternal body mass index (BMI) up to 40 kg/m² was allowed. Laparotomy-assisted fetoscopic spina bifida repair was performed, with carbon dioxide insufflation via two 12-French ports in the exteriorized uterus. All patients received the same peri- and postoperative tocolysis regimen, including magnesium sulfate, nifedipine and indomethacin. Postoperative follow-up ultrasound scans were performed either weekly (< 32 weeks' gestation) or twice a week (≥ 32 weeks). Perinatal outcome was compared between patients with a preoperative cervical length of 25-30 mm vs those with a cervical length > 30 mm. Logistic regression analyses and generalized linear mixed regression analyses were used to predict delivery at less than 30, 34 and 37 weeks' gestation.

RESULTS

The study included 99 patients with a preoperative cervical length > 30 mm and 12 patients with a cervix 25-30 mm in length. One further case which underwent spina bifida repair was excluded because cervical length was measured > 1 week before surgery. No differences in maternal demographics, gestational age (GA) at surgery, duration of surgery or duration of carbon dioxide uterine insufflation were observed between groups. Cases with low-normal cervical length had an earlier GA at delivery (median (range), 35.2 (25.1-39.7) weeks vs 38.2 (26.0-40.9) weeks; P = 0.01), higher rates of delivery at < 34 weeks (41.7% vs 10.2%; P = 0.01) and < 30 weeks (25.0% vs 1.0%; P < 0.01) and a higher rate of preterm prelabor rupture of membranes (PPROM) (58.3% vs 26.3%; P = 0.04) at an earlier GA (mean ± SD, 29.3 ± 4.0 weeks vs 33.0 ± 2.4 weeks; P = 0.05) compared to those with a normal cervical length. Neonates of cases with low-normal cervical length had a longer stay in the neonatal intensive care unit (20 (7-162) days vs 9 (3-253) days; P = 0.02) and higher rates of respiratory distress syndrome (50.0% vs 14.4%; P < 0.01), sepsis (16.7% vs 1.0%; P = 0.03), necrotizing enterocolitis (16.7% vs 0%; P = 0.01) and retinopathy (33.3% vs 1.0%; P < 0.01). There was an association between preoperative cervical length and risk of delivery at < 30 weeks which was significant only for patients with a maternal BMI < 25 kg/m² (odds ratio, 0.37 (95% CI, 0.07-0.81); P = 0.02).

CONCLUSIONS

Low-normal cervical length (25-30 mm) as measured before in-utero laparotomy-assisted fetoscopic spina bifida repair may increase the risk of adverse perinatal outcomes, including PPROM and preterm birth, leading to higher rates of neonatal complications. These data warrant further research and are of critical relevance for clinical teams considering the eligibility of patients for in-utero spina bifida repair. Based on this evidence, patients with a low-normal cervical length should be aware of their increased risk for adverse perinatal outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Neuroprotection is improved by watertightness of fetal spina bifida repair in the sheep model

OBJECTIVES

A contributing factor to unsuccessful prenatal spina bifida aperta (SBA) repair via an open approach may be incomplete neurosurgical repair causing persistent in-utero leakage of cerebrospinal fluid (CSF) and exposure of the fetal spinal cord to amniotic fluid. We aimed to investigate the neurostructural and neurofunctional efficacy of watertight prenatal SBA repair in a validated SBA fetal lamb model.

METHODS

A well-powered superiority study was conducted in the validated SBA fetal lamb model (n = 7 per group). The outcomes of lambs which underwent watertight or non-watertight multilayer repair through an open approach were compared to those of unrepaired SBA lambs (historical controls) at delivery (term = 145 days). At ∼75 days, fetal lambs underwent standardized induction of lumbar SBA. At ∼100 days, they were assigned to an either watertight or non-watertight layered repair group based on an intraoperative watertightness test using subcutaneous fluorescein injection. At 1-2 days postnatally, as primary outcome, we assessed reversal of hindbrain herniation using magnetic resonance imaging (MRI). Secondary proxies of neuroprotection were: absence of CSF leakage at the repair site; hindlimb motor function based on joint-movement score, locomotor grade and Motor Evoked Potential (MEP); four-score neuroprotection scale, encompassing live birth, complete hindbrain herniation reversal, absence of CSF leakage and joint-movement score ≥ 9/15; and brain and spinal cord histology and immunohistochemistry. As the watertightness test cannot be used clinically due to its invasiveness, we developed a potential surrogate intraoperative three-score skin-repair-quality scale based on visual assessment of the quality of the skin repair (suture inter-run distance ≤ 3 mm, absence of tear and absence of ischemia), with high quality defined by a score ≥ 2/3 and low quality by a score < 2/3, and assessed its relationship with improved outcome.

RESULTS

Compared with unrepaired lambs, lambs with watertight repair achieved a high level of neuroprotection (neuroprotection score of 4/4 in 5/7 vs 0/7 lambs) as evidenced by: a significant 100% (vs 14%) reversal of hindbrain herniation on MRI; low CSF leakage (14% vs 100%); better hindlimb motor function, with higher joint-movement score, locomotor grade and MEP area under the curve and peak-to-peak amplitude; higher neuronal density in the hippocampus and corpus callosum; and higher reactive astrogliosis at the SBA lesion epicenter. Conversely, lambs with non-watertight SBA repair did not achieve the same level of neuroprotection (score of 4/4 in 1/7 lambs) compared with unrepaired lambs, with: a non-significant 86% (vs 14%) reversal of hindbrain herniation; high CSF leakage (43% vs 100%); no improvement in motor function; low brain neuron count in both the hippocampus and corpus callosum; and small spinal astroglial cell area at the epicenter. Both watertight layered repair and high (≥ 2/3) intraoperative skin-repair-quality score were associated with improved outcome, but the watertightness test and skin-repair-quality scale could not be used interchangeably due to result discrepancies.

CONCLUSIONS

Watertight layered fetal SBA repair is neuroprotective since it improves brain and spinal-cord structure and function in the fetal lamb model. This translational research has important clinical implications. A neurosurgical technique that achieves watertightness should be adopted in all fetal centers to improve neuroprotection. Future clinical studies could assess whether a high skin-repair-quality score (≥ 2/3) correlates with neuroprotection. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Lifesaving Treatments for the Tiniest Patients-A Narrative Description of Old and New Minimally Invasive Approaches in the Arena of Fetal Surgery

Fetal surgery has become a lifesaving reality for hundreds of fetuses each year. The development of a formidable spectrum of safe and effective minimally invasive techniques for fetal interventions since the early 1990s until today has led to an increasing acceptance of novel procedures by both patients and health care providers. From his vast personal experience of more than 20 years as one of the pioneers at the forefront of clinical minimally invasive fetal surgery, the author describes and comments on old and new minimally invasive approaches, highlighting their lifesaving or quality-of-life-improving potential. He provides easy-to-use practical information on how to perform partial amniotic carbon dioxide insufflation (PACI), how to assess lung function in fetuses with pulmonary hypoplasia, how to deal with giant CPAMS, how to insert shunts into fetuses with LUTO and hydrothorax when conventional devices are not available, and how to resuscitate a fetus during fetal cardiac intervention. Furthermore, the author proposes a curriculum for future fetal surgeons, solicits for the centralization of patients, for adequate maternal counseling, for adequate pain management and adequate hygienic conditions during interventions, and last but not least for starting the process of academic recognition of the matured field as an independent specialty. These steps will allow more affected expectant women and their unborn children to gain access to modern minimally invasive fetal surgery and therapy. The opportunity to treat more patients at dedicated centers will also result in more opportunities for the research of rare diseases and conditions, promising even better pre- and postnatal care in the future.

Fetoscopic Myelomeningocele Repair with Complete Release of the Tethered Spinal Cord Using a Three-Port Technique: Twelve-Month Follow-Up-A Case Report

Open spina bifida is one of the most common congenital defects of the central nervous system. Open fetal surgery, which is one of the available therapeutic options, remains the gold standard for prenatal repairs. Fetoscopic closure may lower the number of maternal complications associated with open fetal surgery. Regardless of the approach, the outcome may be compromised by the development of tethered spinal cord (TSC) syndrome. At 24.2 weeks of gestation, a primipara was admitted due to fetal myelomeningocele and was deemed eligible for fetoscopic repair. Fetal surgery was performed at 25.0 weeks of gestation. It was the first complete untethering of the spinal cord and anatomic reconstruction (dura mater, spinal erectors, skin) achieved during a fetoscopic repair of spina bifida. Cesarean section due to placental abruption was performed at 31.1 weeks of gestation. VP shunting, with no need for revision, was performed at 5 weeks postdelivery due to progressing ventriculomegaly. No clinical or radiological signs of secondary tethering were observed. Neurological examination at 11 months postdelivery revealed cranial nerves without any signs of damage, axial hypotonia, decreased muscle tone in the lower extremities, and absent pathological reflexes. Motor development was slightly retarded. Complete untethering of the neural structures should always be performed, regardless of the surgical approach, as it is the only course of action that lowers the risk for developing secondary TSC.

Association between ambulatory skills and diffusion tensor imaging of corpus callosal white matter in infants with spina bifida

OBJECTIVES

To assess brain white matter using diffusion tensor imaging (DTI) at 1 year of age in infants diagnosed with open neural tube defect (ONTD) and explore the association of DTI parameters with ambulatory skills at 30 months of age.

METHODS

Magnetic resonance imaging (MRI) was performed at an average of 12 months of age and included an echo planar axial DTI sequence with diffusion gradients along 20 non-collinear directions. TORTOISE software was used to correct DTI raw data for motion artifacts, and DtiStudio, DiffeoMap and RoiEditor were used for further postprocessing. DTI data were analyzed in terms of fractional anisotropy (FA), trace, radial diffusivity and axial diffusivity. These parameters reflect the integrity and maturation of white-matter motor pathways. At 30 months of age, ambulation status was evaluated by a developmental pediatrician, and infants were classified as ambulatory if they were able to walk independently with or without orthoses or as non-ambulatory if they could not. Linear mixed-effects method was used to examine the association between study outcomes and study group. Possible confounders were sought, and analyses were adjusted for age at MRI scan and ventricular size by including them in the regression model as covariates.

RESULTS

Twenty patients with ONTD were included in this study, including three cases that underwent postnatal repair and 17 cases that underwent prenatal repair. There were five ambulatory and 15 non-ambulatory infants evaluated at a mean age of 31.5 ± 5.7 months. MRI was performed at 50.3 (2-132.4) weeks postpartum. When DTI analysis results were compared between ambulatory and non-ambulatory infants, significant differences were observed in the corpus callosum (CC). Compared with non-ambulatory infants, ambulatory infants had increased FA in the splenium (0.62 (0.48-0.75) vs 0.41 (0.34-0.49); P = 0.01, adjusted P = 0.02), genu (0.64 (0.47-0.80) vs 0.47 (0.35-0.61); P = 0.03, adjusted P = 0.004) and body (0.55 (0.45-0.65) vs 0.40 (0.35-0.46), P = 0.01, adjusted P = 0.01). Reduced trace was observed in the CC of ambulatory children at the level of the splenium (0.0027 (0.0018-0.0037) vs 0.0039 (0.0034-0.0044) mm² /s; P = 0.04, adjusted P = 0.03) and genu (0.0029 (0.0020-0.0038) vs 0.0039 (0.0033-0.0045) mm² /s; P = 0.04, adjusted P = 0.01). In addition, radial diffusivity was reduced in the CC of the ambulatory children at the level of the splenium (0.00057 (0.00025-0.00089) vs 0.0010 (0.00084-0.00120) mm² /s; P = 0.02, adjusted P = 0.02) and the genu (0.00058 (0.00028-0.00088) vs 0.0010 (0.00085-0.00118) mm² /s; P = 0.02, adjusted P = 0.02). There were no differences in axial diffusivity between ambulatory and non-ambulatory children.

CONCLUSION

This study demonstrates a significant association between white matter integrity of connecting fibers of the corpus callosum, as assessed by DTI, and ambulatory skills at 30 months of age in infants with ONTD. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Primary vs patch-based skin closure for in-utero spina bifida repair

OBJECTIVE

During in-utero spina bifida (SB) repair, closure of large defects is often challenging, requiring tissue graft for watertight skin closure. No prior studies have compared primary skin closure vs patch-based repair. Our objective was to compare neonatal and 1-year outcomes associated with these two types of skin closure for in-utero SB repair.

METHODS

This was a prospective cohort study of 102 patients undergoing open prenatal SB repair from September 2011 to August 2021 at a single institution. All patients met the inclusion criteria of the Management of Myelomeningocele Study (MOMS), and the surgical procedure for in-utero SB repair was similar to that described in the MOMS trial. During the surgery, if primary skin approximation was not feasible due to the large size of the defect, the decision was at the discretion of the pediatric neurosurgeon to utilize a patch for closure. Neonatal outcomes at birth and 1-year outcomes were compared between the primary skin and patch-based closure groups.

RESULTS

Of 102 patients included in the study, 70 (68.6%) underwent primary skin closure and 32 (31.4%) patch-based closure. The patch type included acellular bovine skin matrix (Durepair®; n = 31) and human acellular dermal matrix (Alloderm®; n = 1). Fetuses with myeloschisis were more likely to require patch-based repair than those with myelomeningocele. The median time of fetal repair was 4 min longer for patch-based compared with primary skin closure (37 vs 33 min; P = 0.001). Following patch-based repair, neonates had a longer length of stay in the neonatal intensive care unit (NICU) by 24 days (adjusted risk ratio, 2.40 (95% CI, 1.41-4.29)) compared to those that underwent primary skin closure. There was no difference between the two groups in the other neonatal outcomes, including the need for ventriculoperitoneal shunt placement and cerebrospinal fluid leakage. Outcome at 1 year of age was available for 90 infants. Need for wound revision within their first year after birth was more common in infants who underwent patch-based vs those with primary skin closure (19.4% vs 5.1%; P = 0.05). There was no difference between the two groups in other 1-year outcomes, including the need for ventriculoperitoneal shunt placement by 1 year of age and surgery for tethered cord.

CONCLUSIONS

Patch-based closure during SB repair is often needed in fetuses with myeloschisis and is associated with prolonged fetal surgery time, long NICU stay and need for wound revision within the first year after birth. Further studies are required to identify optimal patches for SB repair or alternative methods to improve outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Minimally Invasive Bimanual Fetal Surgery—A Review

Background: The aim of this review is to discuss experimental and clinical techniques and interventions of fetal surgery which have been performed minimally invasively by the means of a three-port approach for the fetoscope and instruments for the left and right hand of the surgeon (bimanual minimally invasive fetal surgery). Methods: a print and electronic literature search was performed; the titles and abstracts were screened and included reports were reviewed in a two-step approach. First, reports other than minimally invasive fetal surgery were excluded, then a full text review and analysis of the reported data was performed. Results: 17 reports were included. The heterogeneity of the included reports was high. Although reports on human fetoscopic surgical procedures can be found, most of them do not pick out bimanual fetal surgery as a central theme but rather address interventions applying a fetoscope with a working channel for a laser fiber, needle or flexible instrument. Most reports were on experimentation in animal models, the human application of minimally invasive fetoscopic bimanual surgery is rare and has at best been explored for the prenatal treatment of spina bifida. Some reported bimanual fetoscopic procedures were performed on the exteriorized uterus via a maternal laparotomy and can therefore not be classified as being truly minimally invasive. Discussion: our results demonstrate that minimally invasive fetoscopic bimanual surgery is rare, even in animal models, excluding many other techniques and procedures that are loosely termed ‘minimally invasive fetal surgery’ which we suggest to better label as ‘interventions’. Thus, more research on percutaneous minimally invasive bimanual fetoscopic surgery is warranted, with the aim to reduce the maternal, uterine and fetal trauma for correction of congenital malformations.

Percutaneous/mini-laparotomy fetoscopic repair of open spina bifida: a novel surgical technique

Open spina bifida (OSB) is the most common congenital anomaly of the central nervous system compatible with life. Prenatal repair of open spina bifida via open maternal-fetal surgery has been shown to improve postnatal neurological outcomes, including reducing the need for ventriculoperitoneal shunting and improving lower neuromotor function. Fetoscopic repair of OSB minimizes the maternal risks while providing similar neurosurgical outcomes to the fetus. Two fetoscopic techniques are currently in use: (1) the laparotomy-assisted approach, and (2) the percutaneous approach. The laparotomy-assisted fetoscopic technique appears to be associated with less risk of preterm birth compared to the percutaneous approach. However, the percutaneous approach avoids laparotomy and uterine exteriorization, and is associated with less anesthesia risk and improved maternal post-surgical recovery. The purpose of this paper is to describe our experience with a novel surgical approach, which we call percutaneous/mini-laparotomy fetoscopy (PML), in which access to the uterus for one of the ports is done via a mini-laparotomy, while the other ports are inserted percutaneously. This technique draws on the benefits of both the laparotomy-assisted and the percutaneous techniques, while minimizing their drawbacks. This surgical approach may prove invaluable in the prenatal repair of open spina bifida as well as other complex fetal surgical procedures.

Dural substitutes for spina bifida repair: past, present, and future

PURPOSE

The use of materials to facilitate dural closure during spina bifida (SB) repair has been a highly studied aspect of the surgical procedure. The overall objective of this review is to present key findings pertaining to the success of the materials used in clinical and pre-clinical studies. Additionally, this review aims to aid fetal surgeons as they prepare for open or fetoscopic prenatal SB repairs.

METHODS

Relevant publications centered on dural substitutes used during SB repair were identified. Important information from each article was extracted including year of publication, material class and sub-class, animal model used in pre-clinical studies, whether the repair was conducted pre-or postnatally, the bioactive agent delivered, and key findings from the study.

RESULTS

Out of 1,121 publications, 71 were selected for full review. We identified the investigation of 33 different patches where 20 and 63 publications studied synthetic and natural materials, respectively. From this library, 43.6% focused on clinical results, 36.6% focused on pre-clinical results, and 19.8% focused on tissue engineering approaches. Overall, the use of patches, irrespective of material, have shown to successfully protect the spinal cord and most have shown promising survival and neurological outcomes.

CONCLUSION

While most have shown significant promise as a therapeutic strategy in both clinical and pre-clinical studies, none of the patches developed so far are deemed perfect for SB repair. Therefore, there is an opportunity to develop new materials and strategies that aim to overcome these challenges and further improve the outcomes of SB patients.

Controversies in Fetal Surgery: Prenatal Repair of Myelomeningocele in the Modern Era

Fetal surgery is a constantly evolving field that showed noticeable progress with the treatment of myelomeningocele (MMC) using prenatal repair. Despite this success, there are ongoing questions regarding the optimal approach for fetal myelomeningocele repair, as well as which patients are eligible. Expansion of the inclusion and exclusion criteria is an important ongoing area of study for myelomeningocele including the recent Management of Myelomeningocele Plus trial. The significant personal and financial burden required of families seeking treatment has likely limited its accessibility to the general population.

Fetoscopic insufflation of heated-humidified carbon dioxide during simulated spina bifida repair is safe under controlled anesthesia in the fetal lamb

OBJECTIVE

To assess the safety of Partial-Amniotic-Insufflation-of-heated-humidified-CO₂ (hPACI) during fetoscopic spina bifida repair (fSB-repair).

METHOD

A simulated fSB-repair through an exteriorized uterus under hPACI was performed in 100-day fetal lambs (term = 145 days) under a laboratory anesthesia protocol (n = 5; group 1) which is known to induce maternal-fetal acidosis and hypercapnia. Since these may not occur clinically, we applied a clinical anesthesia protocol (n = 5; group 2), keeping maternal parameters within physiological conditions, that is, controlled maternal arterial carbon dioxide (CO2) pressure (pCO₂  = 30 mmHg), blood pressure (≥67 mmHg), and temperature (37.1-39.8°C). Our superiority study used fetal pH as the primary outcome.

RESULTS

Compared to group 1, controlled anesthesia normalized fetal pH (7.23 ± 0.02 vs. 7.36 ± 0.02, p < 0.001), pCO₂ (70.0 ± 9.1 vs. 43.0 ± 1.0 mmHg, p = 0.011) and bicarbonate (27.8 ± 1.1 vs. 24.0 ± 0.9 mmol/L, p = 0.071) at baseline. It kept them within clinically acceptable limits (pH ≥ 7.23, pCO₂  ≤ 70 mmHg, bicarbonate ≤ 30 mm/L) for ≥120 min of hPACI as opposed to ≤30 min in group one. Fetal pO₂ and lactate were comparable between groups and generally within normal range. Fetal brain histology demonstrated fewer apoptotic cells and higher neuronal density in the prefrontal cortex in group two. There was no difference in fetal membrane inflammation, which was mild.

CONCLUSION

Fetoscopic insufflation of heated-humidified CO₂ during simulated fSB-repair through an exteriorized uterus can be done safely under controlled anesthesia.

Complex gastroschisis: a new indication for fetal surgery?

Gastroschisis (GS) is a congenital abdominal wall defect, in which the bowel eviscerates from the abdominal cavity. It is a non-lethal isolated anomaly and its pathogenesis is hypothesized to occur as a result of two hits: primary rupture of the 'physiological' umbilical hernia (congenital anomaly) followed by progressive damage of the eviscerated bowel (secondary injury). The second hit is thought to be caused by a combination of mesenteric ischemia from constriction in the abdominal wall defect and prolonged amniotic fluid exposure with resultant inflammatory damage, which eventually leads to bowel dysfunction and complications. GS can be classified as either simple or complex, with the latter being complicated by a combination of intestinal atresia, stenosis, perforation, volvulus and/or necrosis. Complex GS requires multiple neonatal surgeries and is associated with significantly greater postnatal morbidity and mortality than is simple GS. The intrauterine reduction of the eviscerated bowel before irreversible damage occurs and subsequent defect closure may diminish or potentially prevent the bowel damage and other fetal and neonatal complications associated with this condition. Serial prenatal amnioexchange has been studied in cases with GS as a potential intervention but never adopted because of its unproven benefit in terms of survival and bowel and lung function. We believe that recent advances in prenatal diagnosis and fetoscopic surgery justify reconsideration of the antenatal management of complex GS under the rubric of the criteria for fetal surgery established by the International Fetal Medicine and Surgery Society (IFMSS). Herein, we discuss how conditions for fetoscopic repair of complex GS might be favorable according to the IFMSS criteria, including an established natural history, an accurate prenatal diagnosis, absence of fully effective perinatal treatment due to prolonged need for neonatal intensive care, experimental evidence for fetoscopic repair and maternal and fetal safety of fetoscopy in expert fetal centers. Finally, we propose a research agenda that will help overcome barriers to progress and provide a pathway toward clinical implementation. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Experience of 300 cases of prenatal fetoscopic open spina bifida repair: report of the International Fetoscopic Neural Tube Defect Repair Consortium

BACKGROUND

The multicenter randomized controlled trial Management of Myelomeningocele Study demonstrated that prenatal repair of open spina bifida by hysterotomy, compared with postnatal repair, decreases the need for ventriculoperitoneal shunting and increases the chances of independent ambulation. However, the hysterotomy approach is associated with risks that are inherent to the uterine incision. Fetal surgeons from around the world embarked on fetoscopic open spina bifida repair aiming to reduce maternal and fetal/neonatal risks while preserving the neurologic benefits of in utero surgery to the child.

OBJECTIVE

This study aimed to report the main obstetrical, perinatal, and neurosurgical outcomes in the first 12 months of life of children undergoing prenatal fetoscopic repair of open spina bifida included in an international registry and to compare these with the results reported in the Management of Myelomeningocele Study and in a subsequent large cohort of patients who received an open fetal surgery repair.

STUDY DESIGN

All known centers performing fetoscopic spina bifida repair were contacted and invited to participate in a Fetoscopic Myelomeningocele Repair Consortium and enroll their patients in a registry. Patient data entered into this fetoscopic registry were analyzed for this report. Fisher exact test was performed for comparison of categorical variables in the registry with both the Management of Myelomeningocele Study and a post-Management of Myelomeningocele Study cohort. Binary logistic regression analyses were used to assess the registry data for predictors of preterm birth at <30 weeks' gestation, preterm premature rupture of membranes, and need for postnatal cerebrospinal fluid diversion in the fetoscopic registry.

RESULTS

There were 300 patients in the fetoscopic registry, 78 in the Management of Myelomeningocele Study, and 100 in the post-Management of Myelomeningocele Study cohort. The 3 data sets showed similar anatomic levels of the spinal lesion, mean gestational age at delivery, distribution of motor function compared with upper anatomic level of the lesion in the neonates, and perinatal death. In the Management of Myelomeningocele Study (26.16±1.6 weeks) and post-Management of Myelomeningocele Study cohort (23.3 [20.2-25.6] weeks), compared with the fetoscopic registry group (23.6±1.4 weeks), the gestational age at surgery was lower (comparing fetoscopic repair group with the Management of Myelomeningocele Study; P<.01). After open fetal surgery, all patients were delivered by cesarean delivery, whereas in the fetoscopic registry approximately one-third were delivered vaginally (P<.01). At cesarean delivery, areas of dehiscence or thinning in the scar were observed in 34% of cases in the Management of Myelomeningocele Study, in 49% in the post-Management of Myelomeningocele Study cohort, and in 0% in the fetoscopic registry (P<.01 for both comparisons). At 12 months of age, there was no significant difference in the number of patients requiring treatment for hydrocephalus between those in the fetoscopic registry and the Management of Myelomeningocele Study.

CONCLUSION

Prenatal and postnatal outcomes up to 12 months of age after prenatal fetoscopic and open fetal surgery repair of open spina bifida are similar. Fetoscopic repair allows for having a vaginal delivery and eliminates the risk of uterine scar dehiscence, therefore protecting subsequent pregnancies of unnecessary maternal and fetal risks.

Two-port, exteriorized uterus, fetoscopic meningomyelocele closure has fewer adverse neonatal outcomes than open hysterotomy closure

BACKGROUND

In utero closure of meningomyelocele using an open hysterotomy approach is associated with preterm delivery and adverse neonatal outcomes.

OBJECTIVE

This study compared the neonatal outcomes in in utero meningomyelocele closure using a 2-port, exteriorized uterus, fetoscopic approach vs the conventional open hysterotomy approach.

STUDY DESIGN

This retrospective cohort study included all consecutive patients who underwent in utero meningomyelocele closure using open hysterotomy (n=44) or a 2-port, exteriorized uterus, fetoscopic approach (n=46) at a single institution between 2012 and 2020. The 2-port, exteriorized uterus, fetoscopic closure was composed of the following 3 layers: a bovine collagen patch, a myofascial layer, and a skin. The frequency of respiratory distress syndrome and a composite of other adverse neonatal outcomes, including retinopathy of prematurity, periventricular leukomalacia, and perinatal death, were compared between the study groups. Regression analyses were performed to determine any association between the fetoscopic closure and adverse neonatal outcomes, adjusted for several confounders, including gestational age of <37 weeks at delivery.

RESULTS

The fetoscopic closure was associated with a lower rate of respiratory distress syndrome than the open hysterotomy closure (11.5% [5 of 45] vs 29.5% [13 of 44]; P=.037). The proportion of neonates with a composite of other adverse neonatal outcomes in the fetoscopic group was half of that observed patients in the open hysterotomy group; however, this difference did not reach statistical significance (4.3% [2 of 46] vs 9.1% [4 of 44]; P=.429). Here, regression analysis has demonstrated that fetoscopic meningomyelocele closure was associated with a lower risk of respiratory distress syndrome (adjusted odds ratio, 0.23; 95% confidence interval, 0.06-0.84; P=.026) than open hysterotomy closure.

CONCLUSION

In utero meningomyelocele closure using a 2-port, exteriorized uterus, fetoscopic approach was associated with a lower risk of respiratory distress syndrome than the conventional open hysterotomy meningomyelocele closure.

The effects of cold, dry and heated, humidified amniotic insufflation on sheep fetal membranes

INTRODUCTION

Uterine distension with pressurised carbon dioxide (CO₂) (amniotic insufflation) is used clinically to improve visibility during keyhole fetal surgery. However, there are concerns that amniotic insufflation with unconditioned (cold, dry) CO₂ damages the fetal membranes which leads to post-operative preterm prelabour rupture of membranes (iatrogenic PPROM). We assessed whether heating and humidifying the insufflated CO₂ could reduce fetal membrane damage in sheep.

METHODS

Thirteen pregnant ewes at 103-106 days gestation underwent amniotic insufflation with cold, dry (22 °C, 0-5% humidity, n = 6) or heated, humidified (40 °C, 95-100% humidity, n = 7) CO₂ at 15 mmHg for 180 min. Twelve non-insufflated amniotic sacs acted as controls. Fetal membrane sections were collected after insufflation and analysed for molecular and histological markers of cell damage (caspase 3 and high mobility group box 1 [HMGB1]), inflammation (interleukin 1-alpha [IL1-alpha], IL8 and vascular cell adhesion molecule [VCAM]) and collagen weakening (matrix metalloprotease 9 [MMP9]).

RESULTS

Exposure to cold, dry CO₂ increased mRNA levels of caspase 3, HMGB1, IL1-alpha, IL8, VCAM and MMP9 and increased amniotic epithelial caspase 3 and HMGB1 cell counts relative to controls. Exposure to heated, humidified CO₂ also increased IL8 levels relative to controls however, HMGB1, IL1-alpha and VCAM mRNA levels and amniotic epithelial HMGB1 cell counts were significantly lower than the cold, dry group.

DISCUSSION

Amniotic insufflation with cold, dry CO₂ damaged the amniotic epithelium and induced fetal membrane inflammation. Heated, humidified insufflation partially mitigated this damage and inflammation in sheep and may prove an important step in reducing the risk of iatrogenic PPROM following keyhole fetal surgery.

Economic analysis of prenatal fetoscopic vs open-hysterotomy repair of open neural tube defect

OBJECTIVE

Fetal repair of an open neural tube defect (ONTD) by open hysterotomy has been shown to reduce the need for ventriculoperitoneal shunting and improve motor outcomes for infants, but increases the risk of Cesarean section and prematurity. Fetoscopic repair is an alternative approach that may confer similar neurological benefits but allows for vaginal delivery and reduces the incidence of hysterotomy-related complications. We sought to compare the costs of care from fetal surgery until neonatal discharge, as well as the clinical outcomes, associated with each surgical approach.

METHODS

This was a retrospective cohort study of patients who underwent prenatal ONTD repair, using either the open-hysterotomy or the fetoscopic approach, at a single institution between 2012 and 2018. Clinical outcomes were collected by chart review. A cost-consequence analysis was conducted from the hospital perspective, and included all inpatient and ambulatory hospital and physician costs incurred for the care of mothers and their infants, from the time of maternal admission for fetal ONTD repair up to postnatal maternal and infant discharge. Costs were estimated using cost-to-charge ratios for hospital billing and the Medicare physician fee schedule for physician billing.

RESULTS

Seventy-eight patients were included in the analysis, of whom 47 underwent fetoscopic repair and 31 underwent open-hysterotomy repair. In the fetoscopic-repair group, compared with the open-repair group, fewer women underwent Cesarean section (53% vs 100%; P < 0.001) and the median gestational age at birth was significantly higher (38.1 weeks (interquartile range (IQR), 35.2-39.1 weeks) vs 35.7 weeks (IQR, 33.9-37.0 weeks); P < 0.001). No case of uterine dehiscence was observed in the fetoscopic-repair group, compared with an incidence of 16% in the open-repair group. After adjusting for baseline characteristics, there was no significant difference in the total cost of care between the fetoscopic-repair and the open-repair groups (median, $76 978 (IQR, $60 312-$115 386) vs $65 103 (IQR, $57 758-$108 103); P = 0.458).

CONCLUSIONS

Fetoscopic repair of ONTD, when compared with the open-hysterotomy approach, reduces the incidence of Cesarean section and preterm delivery with no significant difference in total costs of care from surgery to infant discharge. This novel approach may represent a cost-effective alternative to improve maternal and neonatal outcomes for this high-risk population. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Doppler changes in umbilical artery, middle cerebral artery, cerebroplacental ratio and ductus venosus during open fetal microneurosurgery for intrauterine open spina bifida repair

OBJECTIVE

To describe changes in fetal Doppler parameters during a novel technique for open fetal microneurosurgery for open spina bifida (OSB) repair.

METHODS

This was a prospective study of 44 fetuses undergoing open fetal surgery for OSB repair using a novel microneurosurgery approach that is characterized by a mini-hysterotomy (diameter of 15 mm), minimal fetal manipulation and maintenance of a constant normal amniotic fluid volume throughout the procedure. Doppler velocimetry of the umbilical artery (UA), fetal middle cerebral artery (MCA) and ductus venosus (DV) was performed before the start of surgery and at prespecified timepoints during fetal surgery. UA pulsatility index (PI) > 95^th percentile, DV-PI > 95^th percentile, MCA-PI < 5^th percentile and cerebroplacental ratio (CPR) < 5^th percentile were considered abnormal.

RESULTS

Median gestational age at fetal surgery was 25.2 weeks (range, 22.9-27.9 weeks). Doppler recordings were successfully obtained in all cases during all timepoints throughout the surgery. As compared with Doppler values before surgery, there was a significant increase in the proportion of fetuses with MCA-PI < 5^th percentile (63.6% vs 13.6%; P < 0.001), CPR < 5^th percentile (65.9% vs 15.9%; P < 0.001) and DV-PI > 95^th percentile (22.7% vs 0%; P = 0.01) and a non-significant increase in the proportion of fetuses with UA-PI > 95^th percentile (11.4% vs 0%; P = 0.12) during fetal surgery. None of the fetuses showed absent or reversed end-diastolic velocity in the UA or absent or reversed DV a-wave at any stage during OSB repair. All abnormal Doppler parameters returned to normal after surgery.

CONCLUSIONS

During open fetal surgery for OSB repair, a small hysterotomy, reduced fetal manipulation and maintenance of a normal amniotic fluid volume seem to prevent severe fetal Doppler abnormalities. The mild Doppler changes observed during fetal surgery could be a manifestation of fetal adaptation to the stress of fetal surgery. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of the volume of the myelomeningocele sac on imaging, prenatal neurosurgery and motor outcomes: a retrospective cohort study

To investigate the association of the myelomeningocele (MMC) volume with prenatal and postnatal motor function (MF) in cases who underwent a prenatal repair. Retrospective cohort study (11/2011 to 03/2019) of 63 patients who underwent a prenatal MMC repair (37 fetoscopic, 26 open-hysterotomy). At referral, measurements of the volume of MMC was performed based on ultrasound scans. A large MMC was defined as greater than the optimal volume threshold (ROC analysis) for the prediction of intact MF at referral (2.7 cc). Prenatal or postnatal intact motor function (S1) was defined as the observation of plantar flexion of the ankle based on ultrasound scan or postnatal examination. 23/63 participants presented a large MMC. Large MMC lesions was associated with an increased risk of having clubfeet by 9.5 times (CI%95[2.1–41.8], p < 0.01), and reduces the chances of having an intact MF at referral by 0.19 times (CI%95[0.1–0.6], p < 0.01). At birth, a large MMC reduces the chance of having an intact MF by 0.09 times (CI%95[0.01–0.49], p < 0.01), and increases the risk of having clubfeet by 3.7 times (CI%95[0.8–18.3], p = 0.11). A lower proportion of intact MF and a higher proportion of clubfeet pre- or postnatally were observed in cases with a large MMC sac who underwent a prenatal repair.

Trial registration: Clinicaltrials.gov NCT02230072 and NCT03794011 registered on September 3rd, 2014 and January 4th, 2019.

Fetoscopic myelomeningocoele closure: Is the scientific evidence enough to challenge the gold standard for prenatal surgery?

Since the completion of the Management of Myelomeningocoele Study, maternal-fetal surgery for spina bifida has become a valid option for expecting parents. More recently, multiple groups are exploring a minimally invasive approach and recent outcomes have addressed many of the initial concerns with this approach. Based on a previously published framework, we attempt to delineate the developmental stage of the surgical techniques. Furthermore, we discuss the barriers of performing randomized controlled trials comparing two surgical interventions and suggest that data collection through registries is an alternative method to gather high-grade evidence.

Validation of a high-fidelity training model for fetoscopic spina bifida surgery

Open fetal surgery for spina bifida (SB) is safe and effective yet invasive. The growing interest in fetoscopic SB repair (fSB-repair) prompts the need for appropriate training. We aimed to develop and validate a high-fidelity training model for fSB-repair. fSB-repair was simulated in the abdominal cavity and on the stomach of adult rabbits. Laparoscopic fetal surgeons served either as novices (n = 2) or experts (n = 3) based on their experience. Technical performance was evaluated using competency Cumulative Sum (CUSUM) analysis and the group splitting method. Main outcome measure for CUSUM competency was a composite binary outcome for surgical success, i.e. watertight repair, operation time ≤ 180 min and Objective-Structured-Assessment-of-Technical-Skills (OSATS) score ≥ 18/25. Construct validity was first confirmed since competency levels of novices and experts during their six first cases using both methods were significantly different. Criterion validity was also established as 33 consecutive procedures were needed for novices to reach competency using learning curve CUSUM, which is a number comparable to that of clinical fSB-repair. Finally, we surveyed expert fetal surgeons worldwide to assess face and content validity. Respondents (26/49; 53%) confirmed it with ≥ 71% of scores for overall realism ≥ 4/7 and usefulness ≥ 3/5. We propose to use our high-fidelity model to determine and shorten the learning curve of laparoscopic fetal surgeons and retain operative skills.