The EXIT procedure: principles, pitfalls, and progress

Although performing procedures on a fetus before severing the umbilical cord has previously been reported, the principles of the ex utero intrapartum treatment (EXIT) procedure were first fully developed for reversing tracheal occlusion in fetuses with severe congenital diaphragmatic hernia. The EXIT procedure offers the advantage of insuring uteroplacental gas exchange while on placental support. The lessons learned in the development of the principles that underlie the EXIT procedure have improved outcomes when applied in other conditions, most notably in cases of airway obstruction. The range of indications for the EXIT procedure has expanded and currently includes giant fetal neck masses, lung or mediastinal tumors, congenital high airway obstruction syndrome, and EXIT to ECMO (extracorporeal membrane oxygenation), among others. This review summarizes the underlying principles of the EXIT procedure, the expanding indications for its use, the pitfalls of management, and the progress that has been made in its successful application.

Mesenchymal hamartoma of the chest wall

Mesenchymal hamartoma of the chest wall is an unusual lesion remarkable for its occurrence in early infancy and alarming clinical presentation, which often suggests malignancy. Despite its aggressive appearance and propensity to attain massive size, the lesion behaves biologically in a benign fashion, and may be treated conservatively, provided that there is no respiratory compromise secondary to mass effect. The case of an incompletely resected mesenchymal hamartoma that has behaved in a benign fashion after more than 4 years of follow-up is discussed here. We present this case to provide insight and raise clinicians' awareness of the behavior of an extremely rare tumor.

Severe pulmonary hypoplasia associated with giant cervical teratomas

BACKGROUND

The use of the ex utero intrapartum treatment (EXIT) procedure has salvaged many fetuses with giant neck masses. Despite an adequate airway, a subset of these patients die from an inability to achieve adequate gas exchange.

METHODS

We reviewed our experience with the EXIT procedure from 1996 to 2004. The EXIT was used to deliver 23 fetuses with giant neck masses.

RESULTS

Three fetuses with giant cervical teratomas died of severe pulmonary hypoplasia. On postmortem, these patients had severe airway distortion by the mass. The carina was retracted superiorly to the first or second rib resulting in compression of the lungs in the apices of the chest and pulmonary hypoplasia. Hypoplasia was reflected in the lung weights of 24 vs 38 g and 17 vs 34 g for age-matched normal lung.

CONCLUSIONS

Unsuspected obstructive fetal neck masses can be fatal because of an inability to secure an airway. Prenatal ultrasonography can identify fetuses at risk, allowing the fetus to be salvaged using the EXIT procedure. Despite obtaining airway control, a subset of these patients will die because of pulmonary hypoplasia. When counseling patients with large cervical masses it is important to discuss potential pulmonary hypoplasia in these patients.

Twin-twin transfusion syndrome: where do we go from here?

Management of Twin-Twin Transfusion Syndrome (TTTS) is one of the most challenging clinical problems concerning multiple gestations. The pathophysiology of TTTS and Quintero staging system are described. The importance of fetal echocardiograms in assessing prognosis and response to therapy is highlighted. Treatment modalities, particularly amnioreduction, microseptostomy, and fetoscopic laser photocoagulation, are discussed. Questions still remain as to how various treatment options affect short- and long-term cardiac and neurodevelopmental outcomes and which patients will benefit most from selective laser photocoagulation therapy.

Impact of Continuous Intraoperative Monitoring on Outcomes in Open Fetal Surgery

OBJECTIVES

There are shifts in fetal hemodynamics during open fetal surgery that were not appreciated until the use of intraoperative fetal echocardiography. We have developed an intraoperative monitoring strategy to continuously assess fetal hemodynamics. We hypothesized that this approach would enhance intraoperative management and survival.

METHODS

Medical records of open fetal surgery patients were reviewed since the implementation of this approach. Intraoperative fetal monitoring was accomplished by continuous echocardiography, pulse oximetry, establishment of intravenous access, and arterial blood gas and hemoglobin measurement. Overall survival was compared to fetal surgeries performed prior implementation of this monitoring strategy.

RESULTS

Resections of a congenital cystic adenomatoid malformation or a sacrococcygeal teratoma in nine hydropic fetuses were performed while using this monitoring strategy. Intraoperative echocardiography resulted in a change of management in 7 of 9 fetuses. The main observations on fetal echocardiography resulting in intraoperative intervention were decreased ventricular filling, bradycardia, and decreased ventricular contractility. Therapy included administration of volume expanders and/or inotropic agents. Overall fetal survival was 78% compared to a survival of 42% prior to the implementation of this approach.

CONCLUSION

Continuous intraoperative fetal monitoring provides real time assessment of fetal hemodynamics which results in changes in intraoperative management. The overall outcomes in these critically ill fetuses have been improved.

The ex utero intrapartum therapy procedure for high-risk fetal lung lesions

BACKGROUND

Indications for the ex utero intrapartum therapy (EXIT) procedure have expanded to include any fetal anomaly in which resuscitation of the neonate may be compromised.

METHODS

We reviewed the medical records of 9 patients after resection of lung lesions during the EXIT procedure.

RESULTS

The mean gestational age at EXIT procedure was 35.4 weeks. All lung masses maintained large sizes late into gestation with mean mass volume/head circumference ratio of 2.5 at presentation and 2.2 at EXIT. Seven of 9 fetuses demonstrated hydropic changes (n = 6) and/or polyhydramnios (n = 5), and underwent prenatal intervention including thoracentesis, thoracoamniotic shunt placement, amnioreduction, and/or betamethasone administration. Overall survival after EXIT for lung mass resection was 89%. The average time on placental bypass was 65 minutes. Postnatal complications included reoperation for air leak (n = 1), reoperation for bleeding (n = 1), and death from sepsis and prematurity (n = 1). Venoarterial extracorporeal membrane oxygenation was used in 4 neonates for persistent pulmonary hypertension. Maternal prenatal complications included polyhydramnios (n = 5), preterm labor (n = 4), and chorioamnionitis (n = 1). One mother required perioperative blood transfusion.

CONCLUSION

The EXIT procedure allows for controlled resection of large fetal lung lesions at delivery, avoiding acute respiratory decompensation related to mediastinal shift, air trapping, and compression of normal lung.

Management of fetal mediastinal teratoma

BACKGROUND/PURPOSE

Mediastinal teratomas are rare congenital germ cell tumors that prenatally can compress mediastinal structures and cause hydrops. Two possible presentations of massive fetal mediastinal teratoma include hydrops leading to fetal demise, or fetal esophageal and airway compression causing late-gestation polyhydramnios and preterm labor. The authors present 2 cases of fetal mediastinal teratoma that illustrate successful strategies for either of these presentations.

METHODS

A 37-year-old woman carrying a fetus with a mediastinal mass and secondary hydrops at 23 weeks of gestation underwent in utero resection of the mass. Delivery was by cesarean delivery at 25 weeks because of preterm labor. A 24-year-old mother carrying a fetus with a mediastinal mass and severe polyhydramnios at 36 weeks of gestation underwent an ex utero intrapartum therapy procedure for establishment of an airway and tumor resection on uteroplacental support.

RESULTS

These strategies resulted in physiologic improvement in the first case and controlled resection and resuscitation in the second. The first patient had significant sequelae of prematurity including bronchopulmonary dysplasia but is currently well at 9 months of age. The second patient is well at 1 year of age.

CONCLUSIONS

Massive fetal mediastinal teratoma can result in fetal or neonatal mortality by a variety of mechanisms. Optimal prenatal and perinatal management is required to salvage fetuses compromised by this lesion.

Prenatal Diagnosis and Management of Mainstem Bronchial Atresia

The prenatal diagnosis, natural history and management of mainstem bronchial atresia have not been described previously. We report two cases of prenatally diagnosed proximal bronchial atresia. The first patient presented at 18 weeks with sonographic and MRI findings consistent with bronchial atresia with fetal hydrops. The mother developed the mirror syndrome and labor was induced. A non-viable fetus was delivered at 25 weeks. The second patient presented at 16 weeks gestation with evidence of an intrathoracic mass that was subsequently prenatally diagnosed as a right mainstem bronchial atresia. The right lung increased rapidly in size and was associated with the onset of fetal hydrops. At 24 weeks, fetal pneumonectomy was performed but the fetus expired intraoperatively due to cardiovascular collapse. Post-mortem findings in both cases confirmed the presence of an atretic mainstem bronchus with massive enlargement of the lung. Bronchial atresia involving the mainstem bronchus is associated with a poor prognosis.

Prenatally diagnosed giant omphaloceles: short- and long-term outcomes

OBJECTIVES

To review prenatal findings, short- and long-term outcomes of giant omphaloceles (GO) managed at a single institution (1996-2001).

METHODS

Prenatal findings and early postnatal outcomes were retrospectively reviewed. Clinical short- and long-term outcomes were analyzed in eight and five children respectively. Parents and physicians of the children were surveyed by written questionnaires about the children's subsequent health issues. (IRB 2002-2-2683).

RESULTS

Seventeen pregnancies with GO were identified: Eight fetuses were live born, four ended in (terminations), two died in utero and three were lost to follow-up. Live-born fetuses had prenatal ascites, extreme levocardia and were delivered by cesarean section at a mean of 37 weeks' gestation with a mean birth weight of 2903 g. All neonates required intubation. Two infants (2/8) died within one year. Four of the six survivors had respiratory insufficiency with a mean ventilation time of 76 days. Respiratory and feeding problems complicated the early neonatal course. Long-term follow-up was available for five patients (mean age of 33.2 months). Asthma, recurrent pulmonary infections, feeding problems, gastroesophageal reflux and failure to thrive were the major problems.

CONCLUSIONS

Respiratory and feeding problems were the most common neonatal and long-term medical management issues. Parents need to be counseled prenatally about the probability of multiple surgeries and long hospitalization following birth.

Adenoviral mediated gene transfer of PDGF-B enhances wound healing in type I and type II diabetic wounds

We have shown that the genetically diabetic mouse (C57BLKS/J-m+/+Lepr(db)) has a wound healing and neovascularization deficit associated with an inability to recruit endothelial precursor cells (EPCs) to the wound. This may account for a fundamental mechanism in impaired diabetic wound healing. We hypothesized that the adenoviral mediated overexpression of platelet-derived growth factor-B (PDGF-B) would enhance wound healing, improve neovascularization, and recruit EPCs to the epithelial wound in three diabetic mouse models. Eight-mm full-thickness flank wounds were made in db/db, nonobese NOD/Ltj, streptozotocin, and C57BLKS/J mice. Wounds were treated with either 1 x 10(8) PFU Ad-PDGF-B or Ad LacZ or phosphate buffered saline solution. Wounds harvested at seven days were analyzed for epithelial gap, blood vessel density, granulation tissue area, and EPCs per high powered field. All three diabetic models have a significant wound healing and neovascularization defect compared to C57BLKS/J controls. Adenoviral-PDGF-B treatment significantly enhanced epithelial gap closure in db/db, streptozotocin, and nonobese NOD/Ltj mice as compared to diabetic phosphate buffered saline solution or Ad LacZ controls. A similar increase in the formation of granulation tissue and vessel density was also observed. All three models had reduced levels of GATA-2 positive EPCs in the wound bed that was corrected by the adenoviral mediated gene transfer of PDGF. EPC recruitment was positively correlated with neovascularization and wound healing. Three different diabetic models have a wound healing impairment and a decreased ability to recruit EPCs. The vulnerary effect of adenoviral mediated gene therapy with PDGF-B significantly enhanced wound healing and neovascularization in diabetic wounds. The PDGF-B mediated augmentation of EPC recruitment to the wound bed may be a fundamental mechanism of these results.

Reproductive outcomes after pregnancy complicated by maternal-fetal surgery

OBJECTIVE

The reproductive outcomes for women after the pregnancy complicated by maternal-fetal surgery were evaluated to obtain evidence-based information for prenatal risk counseling.

STUDY DESIGN

The retrospective review identified 83 women with maternal-fetal surgery from a single institution (1996-2002). These women were sent a consent form and a questionnaire to document postoperative problems, fertility, obstetric outcomes, and psychosocial concerns in pregnancy after the index fetal therapy. Institutional Review Board approval was obtained from Committee for Protection of Human Subjects.

RESULTS

The total return rate was 55 (66%). The pregnancy rate was 62% (18% spontaneous abortion, 24% preterm delivery, and 58% term delivery). Complications were reported in 12 of 34 pregnancies (35%), including uterine dehiscence/rupture (12%/6%), cesarean hysterectomy (3%), and antepartum hemorrhage requiring transfusion (9%).

CONCLUSION

The reproductive outcome of uterine dehiscence, rupture, and hysterectomy was 12%, 6%, and 3%, respectively, after a pregnancy complicated by maternal-fetal surgery. The uterine rupture rate is similar to the rupture rate after "classical" cesarean section (4%-9%).

Acute Cardiovascular Effects of Fetal Surgery in the Human

Background— Prenatal surgery for congenital anomalies can prevent fetal demise or alter the course of organ development, resulting in a more favorable condition at birth. The indications for fetal surgery continue to expand, yet little is known about the acute sequelae of fetal surgery on the human cardiovascular system.

Methods and Results— Echocardiography was used to evaluate the heart before, during, and early after fetal surgery for congenital anomalies, including repair of myelomeningocele (MMC, n=51), resection of intrathoracic masses (ITM, n=15), tracheal occlusion for congenital diaphragmatic hernia (CDH, n=13), and resection of sacrococcygeal teratoma (SCT, n=4). Fetuses with MMC all had normal cardiovascular systems entering into fetal surgery, whereas those with ITM, CDH, and SCT all exhibited secondary cardiovascular sequelae of the anomaly present. At fetal surgery, heart rate increased acutely, and combined cardiac output diminished at the time of fetal incision for all groups including those with MMC, which suggests diminished stroke volume. Ventricular dysfunction and valvular dysfunction were identified in all groups, as was acute constriction of the ductus arteriosus. Fetuses with ITM and SCT had the most significant changes at surgery.

Conclusions— Acute cardiovascular changes take place during fetal surgery that are likely a consequence of the physiology of the anomaly and the general effects of surgical stress, tocolytic agents, and anesthesia. Echocardiographic monitoring during fetal surgery is an important adjunct in the management of these patients.

Thoracoamniotic Shunts: Fetal Treatment of Pleural Effusions and Congenital Cystic Adenomatoid Malformations

OBJECTIVE

To determine whether fetuses that underwent thoracoamniotic shunt placement for treatment of pleural effusion (PE) or macrocystic congenital cystic adenomatoid malformation (CCAM) have an improved outcome as compared with an untreated population.

METHODS

A retrospective review from a single tertiary center was performed using thoracoamniotic shunt placement to treat PE or macrocystic CCAM between 1998 and 2001. Thoracoamniotic shunts were used on 26 occasions in 19 pregnancies.

RESULTS

The average gestational age at the diagnosis of PE and CCAM was 22 + 4 and 20 + 0 weeks, respectively. Shunts were offered in pregnancies complicated by hydrops or at significant risk for pulmonary hypoplasia. Shunts were placed at 26 + 2 weeks (average) and 23 + 1 weeks (average) in the PE and CCAM groups, respectively. In CCAM patients, the mean pre- and postshunting mass volumes were 50.5 and 25.7 cm(3), representing a 51% reduction in mass volume following shunt placement. In the PE group, the average delivery age was 33 + 5 weeks, with an average shunt placement to delivery time of 7 + 3 weeks. In the CCAM group, the average delivery was 33 + 3 weeks, with an average shunt placement to delivery time of 10 + 2 weeks. The postnatal survival rates were 67% (6/9) and 70% (7/10) in the PE and CCAM groups, respectively.

CONCLUSIONS

(1) Thoracoamniotic shunts should be considered as a treatment option for selected PE or macrocystic CCAM fetuses with hydrops or a significant risk for pulmonary hypoplasia; (2) the neonatal survival with shunting was similar for PE and CCAM groups and was improved as compared with literature reports, and (3) fetuses with CCAM presented earlier with hydrops than those with PE. Successful shunting resulted in a prolongation of pregnancy into the 3rd trimester in both groups.

Regenerative versus reparative healing in tendon: a study of biomechanical and histological properties in fetal sheep

Previous studies have shown fetal tissues heal in a regenerative fashion without scar formation. The objective of this study is to compare the healing properties of adult and fetal tendons. Time-mated pregnant ewes at 80-85 days of gestation were utilized. A partial, midsubstance tenotomy was performed in the lateral extensor fetal tendons, and analogous tenotomies were created in the maternal limbs. One week after injury, the fetal and adult animals were sacrificed, and tendons were histologically and mechanically evaluated. Immunohistochemical staining for transforming growth factor beta isoform 1 (TGF-beta1) was performed. Histologically, a gap with granulation tissue and inflammatory cells was visible in the site of wounding in the adult tendons. In the fetal tendons, no abnormalities were noted in the wound, with reconstitution of collagen architecture. TGF-beta1 expression was low in fetal but upregulated in the adult wounds. No significant differences were found in the biomechanical properties between groups. We identified regenerative healing properties in injured fetal tendon, while adult tendon tissue healed reparatively with scar formation. Fetal tendons demonstrated a limited recovery of mechanical properties after injury that was no better than that of the adult tendons at seven days. A better understanding of the mechanisms of fetal healing may lead to novel therapeutic strategies in the clinical setting.

Successful management of concommitant blunt injury to the trachea, esophagus, and cervical spine in a 6-year-old girl

A 6-year-old girl sustained an unusual constellation of injuries after blunt trauma sustained in a motor vehicle accident. Transection of the trachea and esophagus were managed successfully by repair through a median sternotomy while the patient was on cardiopulmonary bypass. A cervical spinal injury was fixated with halo traction and a femur fracture with internal fixation.

Hybrid Constructs for Craniofacial Reconstruction: Sustained Gene Delivery Using Demineralized Bone Matrix Putty

These experiments evaluate the efficacy of a demineralized bone matrix putty engineered as a hybrid construct for sustained, site-directed gene transfer using an adenoviral vector. In vitro experiments were performed to evaluate the optimal dosing for gene transfer to fetal calvarial osteoblasts and dural cells and for the sustainability of gene transfer from the hybrid constructs. In the dosing experiments, hybrid constructs were created by combining 0.5 mL of demineralized bone matrix putty (DBX; SYNTHES Maxillofacial, Monument, CO) with 1 x 10(8), 1 x 10(7), or 1 x 10(6) particle-forming units (PFU) of an adenoviral vector carrying the gene encoding green fluorescent protein (AdGFP). These constructs were then placed in direct contact, or in transwell coculture, with fetal murine calvarial osteoblasts or dural cells at a multiplicity of infection (MOI = viral particle/cell ratio) of 1000, 100, and 10. The sustainability of gene transfer was tested through transfer of the hybrid construct to wells containing untransfected cells every 24 hours for 30 days. In both experiments, gene transfer was determined through the visualization of GFP using fluorescence light microscopy 24 hours after the onset of transfection. Optimal dosing for gene transfer occurred at an MOI of 10 for calvarial osteoblasts and 100 for dural cells. At greater concentrations, toxicity was observed in the majority of samples. Gene transfer to fetal dural cells and calvarial osteoblasts was sustained throughout the 30-day period. These experiments suggest that adenoviral vectors could be successfully incorporated within demineralized bone matrix to provide effective, sustained, site-directed gene transfer.

Prenatal MR findings of the middle interhemispheric variant of holoprosencephaly

We report a case of the middle interhemispheric variant of holoprosencephaly (MIH) with noncleavage of the posterior portion of the frontal lobes and the parietal regions in a fetus at 22 weeks' gestation. To our knowledge, this is the first case of the rare MIH variant to be diagnosed in utero by use of ultrafast MR imaging and one of the few such reports to document gross and microscopic pathologic findings. Neuroimaging results correlated with those of gross and microscopic pathologic specimens obtained from the stillborn child. We conclude that ultrafast MR imaging can accurately distinguish holoprosencephaly subtypes in utero, which may affect counseling of parents.

Right congenital diaphragmatic hernia: Prenatal assessment and outcome

PURPOSE

To understand the natural history of right congenital diaphragmatic hernia (CDH), the authors retrospectively reviewed 27 cases of right CDH that presented for prenatal evaluation or postnatal treatment.

METHODS

Between 1995 and September 2002, a total of 194 cases of fetal CDH were evaluated and included 22 right-sided defects. The authors reviewed prenatal diagnostic studies (ultrasound scan, magnetic resonance imaging [MRI] echocardiography) and pre- and postnatal outcomes in these 22 cases of right CDH. Five additional cases of right CDH without a prenatal diagnosis were reviewed.

RESULTS

The mean gestational age at evaluation was 26.1 weeks. The lung area to head circumference ratio (LHR) ranged from 0.32 to 2.5. In all cases, the fetal liver was herniated into the right chest. Associated anomalies were common. There were no karyotype abnormalities (17 of 22 tested). There were 4 terminations. Nine of the 18 (50%) continuing pregnancies had polyhydramnios, premature rupture of membranes, or preterm labor. The mean gestational age at birth was 36.8 weeks. One patient underwent tracheal occlusion at 27 weeks, and 2 patients died before postnatal repair. Overall survival rate (22 prenatal plus 5 postnatal diagnoses) was 19 of 27 (70%). Postnatal survival rate was 19 of 23 (83%). A Gore-tex (W. L. Gore and Associates, Flagstaff, AZ) patch was utilized in 14 of 21 neonates undergoing surgery. Twelve of 23 (52%) required extracorporeal membrane oxygenation (ECMO) with a 75% survival rate. Significant morbidity occurred in 10 of 19 survivors and included neurologic sequelae in 6 of 19 (32%).

CONCLUSIONS

MRI was helpful in the determination of liver position and confirmation of diagnosis. The high incidence of preterm complications, frequent need for ECMO, and high prevalence of comorbidities are indicative of the severity of this CDH population and warrant close prenatal surveillance and delivery at a tertiary care center with ECMO capability.

Sacrococcygeal teratoma: prenatal assessment, fetal intervention, and outcome

PURPOSE

To understand the natural history and define indications for fetal intervention in sacrococcygeal teratoma (SCT), the authors reviewed all cases of fetal SCT presenting for evaluation.

METHODS

Prenatal diagnostic studies including ultrasound scan, magnetic resonance imaging (MRI), echocardiography and pre- and postnatal outcomes were reviewed in 30 cases of SCT that presented between September 1995 and January 2003.

RESULTS

The mean gestational age (GA) at presentation was 23.9 weeks (range, 19 to 38.5) with 3 sets of twins (10%). Overall outcomes included 4 terminations, 5 fetal demises, 7 neonatal deaths, and 14 survivors. Significant obstetric complications occurred in 81% of the 26 continuing pregnancies: polyhydramnios (n = 7), oligohydramnios (n = 4), preterm labor (n = 13), preeclampsia (n = 4), gestational diabetes (n = 1), HELLP syndrome (n = 1), and hyperemesis (n = 1). Fetal intervention included cyst aspiration (n = 6), amnioreduction (n = 3), amnioinfusion (n = 1), and open fetal surgical resection (n = 4). Indications for cyst aspiration and amnioreduction were maternal discomfort, preterm labor, and prevention of tumor rupture at delivery. Although 15 SCTs were solid causing risk for cardiac failure, only 4 fetuses met criteria for fetal debulking based on ultrasonographic and echocardiographic evidence of impending high output failure and favorable anatomy at 21, 23.6, 25, and 26 weeks' gestation. Intraoperative events included maternal blood transfusion (n = 1), fetal blood transfusion (n = 2), chorioamniotic membrane separation (n = 2), and fetal arrest requiring successful cardiopulmonary resuscitation (CPR) (n = 1). In the fetal resection group, 3 of 4 survived with mean GA at delivery of 29 weeks (range, 27.6 to 31.7 weeks), mean birth weight of 1.3 kg, hospital stay ranging from 16 to 34 weeks, and follow-up ranging from 20 months to 6 years. Postnatal complications in the fetal surgery group included neonatal death (n = 1, secondary to premature closure of ductus arteriosus with cardiac failure), embolic event (n = 1, resulting in unilateral renal agenesis, jejunal atresia), chronic lung disease (n = 1), and tumor recurrence (n = 1).

CONCLUSIONS

For fetal SCT, the rapidity at which cardiac compromise can develop and the high incidence of obstetric complications warrant close prenatal surveillance. Amnioreduction, cyst aspiration, and surgical debulking are potentially life-saving interventions.

Gene transfer to the tracheobronchial tree: implications for fetal gene therapy for cystic fibrosis

Gene transfer to the tracheobronchial tree has been an active area of investigation since the discovery of the genetic defect in the cystic fibrosis transmembrane conductance regulator over two decades ago. Cystic fibrosis (CF) is the most common lethal monogeneic disorder for which there is no cure short of lung transplantation. The ultimate goal of gene therapy in CF is to achieve efficient gene transfer at a level and distribution in target tracheobronchial epithelial cells and submucosal gland cells, which results in the genotypic and phenotypic correction of CF. This article reviews the current challenges and limitations of postnatal gene therapy to the tracheobronchial tree, and the potential advantages of fetal gene therapy for CF. We review recent work with novel viral vectors to achieve extremely efficient gene transfer in target cells in the respiratory epithelium and submucosal glands in models that are representative of the developing human fetal trachea. Finally, we will examine the prospects for, limitations of, and regulatory challenges facing the translation of fetal gene therapy from research to clinical application.

Abnormal Umbilical Cord Doppler Sonograms May Predict Impending Demise in Fetuses with Sacrococcygeal Teratoma

OBJECTIVE

To identify factors predictive of fetal demise in fetuses with sacrococcygeal teratoma (SCT).

METHOD

The recent management of monochorionic twins discordant for a large SCT and a singleton with a large SCT was reviewed.

RESULTS

Serial fetal echocardiography and ultrasonography with Doppler flow measurements documented rapid growth of the SCT in both cases with a relatively modest increase in combined cardiac output. No placentomegaly or hydrops was observed at any time. In both fetuses with SCT, evolution of abnormal umbilical artery waveforms was observed with the ultimate development of reversed end-diastolic umbilical arterial flow that was followed by sudden fetal demise.

CONCLUSION

Death in these 2 fetuses with large SCTs in the absence of placentomegaly/hydrops or hemodynamic changes suggestive of evolving high-output failure suggests a previously unrecognized mechanism of death in fetuses with large rapidly growing SCTs. In these cases, fetal demise may only be heralded by abnormal umbilical artery waveforms that progress to the premorbid observation of reversed diastolic umbilical artery blood flow. Umbilical artery waveform analysis should be closely monitored with other hemodynamic parameters in fetuses with large SCTs. In such fetuses, depending on the gestational age, abnormalities in umbilical artery waveform should be considered indications for early delivery or in utero intervention to prevent fetal demise.

Fetal myelomeningocele repair: short-term clinical outcomes

OBJECTIVE

The study was undertaken to evaluate short-term clinical outcomes with antenatal myelomeningocele (MMC) repair.

STUDY DESIGN

Retrospective review of 50 fetuses that underwent open fetal MMC closure was performed. Inclusion criteria included less than 26 weeks' gestation, thoracic to S1 level defect, absent clubfoot deformity, Arnold-Chiari malformation, ventriculomegaly less than 17 mm, normal karyotype, and no other anomalies.

RESULTS

Perinatal survival was 94% (47/50 fetuses). Mean age at delivery was 34 weeks 3 days. All fetuses demonstrated reversal of hindbrain herniation. Forty-three percent of the 50 fetuses have required ventriculoperitoneal shunting compared with 100% thoracic, 88% lumbar, and 68% sacral (85% overall) in 297 historic controls. Better-than-predicted leg function was seen in 57% of thoracic and lumbar level lesion patients.

CONCLUSION

Early experience with fetal MMC repair suggests a decreased need for ventriculoperitoneal shunting, arrest or slowing of progressive ventriculomegaly, and consistent resolution of hindbrain herniation. However, further long-term follow-up is needed to evaluate neurodevelopment and bladder and bowel function.