Correction of congenital diaphragmatic hernia in utero. III. Development of a successful surgical technique using abdominoplasty to avoid compromise of umbilical blood flow

Prenatal diagnostic and intervention considerations in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a life-threatening birth defect with significant morbidity and mortality. The prenatal management of a pregnancy with a fetus affected with CDH is complex and requires a multi-disciplinary team approach. An improved understanding of prenatal diagnosis and management is essential to developing strategies to optimize outcomes for these patients. In this review, we explore the current knowledge on diagnosis, severity stratification, prognostic prediction, and indications for fetal intervention in the fetus with CDH.

The Rearing of Maternal-Fetal Surgery: The Maturation of a Field from Conception to Adulthood

Maternal-fetal surgery is fraught with inherent controversy from within the medical community and general public. Despite these challenges, the field of maternal-fetal surgery evolved into an international enterprise. Carefully nurtured by pioneers with foresight and resilience, the field navigated ethical dilemmas with rigorous scientific methodology, collaboration, transparency, and accordance. These central pillars are consistent throughout the brief but momentous history of maternal-fetal surgery, serving as the catalyst for its success. The maturation of fetal intervention is an exemplar of technological innovation propelling clinical innovation, as well as a celebration of mastering the delicate balance between caution and optimism.

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.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare birth defect characterized by incomplete closure of the diaphragm and herniation of fetal abdominal organs into the chest that results in pulmonary hypoplasia, postnatal pulmonary hypertension owing to vascular remodelling and cardiac dysfunction. The high mortality and morbidity rates associated with CDH are directly related to the severity of cardiopulmonary pathophysiology. Although the aetiology remains unknown, CDH has a polygenic origin in approximately one-third of cases. CDH is typically diagnosed with antenatal ultrasonography, which also aids in risk stratification, alongside fetal MRI and echocardiography. At specialized centres, prenatal management includes fetal endoscopic tracheal occlusion, which is a surgical intervention aimed at promoting lung growth in utero. Postnatal management focuses on cardiopulmonary stabilization and, in severe cases, can involve extracorporeal life support. Clinical practice guidelines continue to evolve owing to the rapidly changing landscape of therapeutic options, which include pulmonary hypertension management, ventilation strategies and surgical approaches. Survivors often have long-term, multisystem morbidities, including pulmonary dysfunction, gastroesophageal reflux, musculoskeletal deformities and neurodevelopmental impairment. Emerging research focuses on small RNA species as biomarkers of severity and regenerative medicine approaches to improve fetal lung development.

Modern fetal surgery-a historical review of the happenings that shaped modern fetal surgery and its practices

The history of fetal surgery is one of constant evolution. Over the last 50 years, fetal surgery has progressed from a mere idea to an internationally respected innovative field of surgery. This article aims to provide a historical review of how the enterprise of maternal-fetal surgery came to be its modern version. This review is less focused on the history of specific therapies for a relatively small number of conditions, and more on how the whole field of maternal-fetal surgery evolved. The various internal and external influences that steered the field's evolution are discussed in chronologic order. Since the start of modern fetal surgery in the 1980s, large paradigm shifts have characterized the growth of the field as a whole. Innovative interventions are now based on physiologic manipulation as opposed to simple anatomic repair, fetoscopy has become the more frequently preferred surgical approach, and rigorous scientific evaluation with randomized controlled trials is now the standard expected by the community. In a very similar fashion to when the field first began in the early 1980s, recently community's leaders have risen to protect the integrity of maternal-fetal surgery by publishing ethical guidelines for innovation and clinical practice. This incredible history of innovation, rigorous science and ethical contemplation is the foundation on which modern maternal-fetal surgery rests.

Prenatal genetic diagnosis: Fetal therapy as a possible solution to a positive test

BACKGROUND

Fetal abnormalities cause 20% of perinatal deaths. Advances in prenatal genetic and other types of screening offer great opportunities for identifying high risk pregnancies.

METHODS

Through a literature search, here we summarise what are the prenatal diagnostic technique that are being used and how those techniques may allow for prenatal interventions.

RESULTS

Next generation sequencing and non-invasive prenatal testing are fundamental for clinical diagnostics because of their sensitivity and accuracy in identifying point mutations, aneuploidies, and microdeletions, respectively. Timely identification of genetic disorders and other fetal abnormalities enables early intervention, such as in-utero gene therapy, fetal drug therapy and prenatal surgery.

CONCLUSION

Prenatal intervention is mainly focused on conditions that may cause death or lifelong disabilities, like spina bifida, congenital diaphragm hernia and sacrococcygeal teratoma; and may be an alternative therapeutic option to termination of pregnancy. However, it is not yet widely available, due to lack of specialized centers.

Prenatal regenerative fetoscopic interventions for congenital anomalies

Fetal intervention has progressed in the past two decades from experimental proof-of-concept to practice-adopted, life saving interventions in human fetuses with congenital anomalies. This progress is informed by advances in innovative research, prenatal diagnosis, and fetal surgical techniques. Invasive open hysterotomy, associated with notable maternal-fetal risks, is steadily replaced by less invasive fetoscopic alternatives. A better understanding of the natural history and pathophysiology of congenital diseases has advanced the prenatal regenerative paradigm. By altering the natural course of disease through regrowth or redevelopment of malformed fetal organs, prenatal regenerative medicine has transformed maternal-fetal care. This review discusses the uses of regenerative medicine in the prenatal diagnosis and management of three congenital diseases: congenital diaphragmatic hernia, lower urinary tract obstruction, and spina bifida.

Fetal tracheal occlusion for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) remains one of the most elusive birth defects to treat. Despite greater knowledge of disease and advances in technology, approximately one-third of CDH children born today still die. Consequently, clinicians and researchers have struggled to find the optimal treatment strategies for CDH. Without further innovations in postnatal treatment, many have focused an antenatal approach to improve pulmonary function. Fetoscopic Endoluminal Tracheal Occlusion (FETO) for CDH has evolved to the bedside after decades of research. While still under clinical investigation, FETO remains a promising adjunct to the treatment of CDH.

Fetal intervention for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a condition that results from incomplete diaphragm formation during embryogenesis. The diaphragmatic defect allows for herniation of abdominal viscera into the chest, and the resulting pulmonary hypoplasia and pulmonary hypertension can lead to cardiorespiratory failure in the neonatal period. There is a wide spectrum of disease severity in CDH, and while advances in neonatal care and the introduction of extracorporeal membrane oxygenation have improved outcomes in many cases, the most severe defects are still associated with high morbidity and mortality. Improvements in prenatal diagnostic and prognostic capabilities have created an opportunity to select high risk patients for fetal intervention. Three decades of refinements in the fetal surgical therapy for CDH have led to the current technique of Fetoscopic Endoluminal Tracheal Occlusion (FETO). Herein, we review the current considerations for selecting patients for fetal intervention, and the contemporary fetal surgical operation for CDH, FETO, with a focus on early outcomes and ongoing studies.

Prenatal intervention for the management of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is the result of incomplete formation of the diaphragm that occurs during embryogenesis. The defect in the diaphragm permits the herniation of abdominal organs into the thoracic cavity contributing to the impairment of normal growth and development of the fetal lung. In addition to the hypoplastic lung, anomalies of the pulmonary arterioles worsen the pulmonary hypertension that can have detrimental effects in severe cases. Most cases of CDH can be effectively managed postnatally. Advances in neonatal and surgical care have resulted in improved outcomes over the years. When available, extracorporeal membrane oxygenation can provide temporary cardiorespiratory support for those not effectively supported by mechanical ventilation. In spite of these advances, very severe cases of CDH still carry a very high mortality and morbidity rate. Advances in imaging and evaluation now allow for early and accurate prenatal diagnosis of CDH, thereby identifying those at greatest risk who may benefit from prenatal intervention. This review article discusses some of the surgical and non-surgical prenatal interventions in the management of isolated severe congenital diaphragmatic hernia.

Evaluation of alveolar epithelial cells in the sheep model of congenital diaphragmatic hernia: Type 1 alveolar epithelial cells and histopathological image analysis

BACKGROUND

There are few reports comparing type 1 alveolar epithelial cell development with histopathological image analysis. We investigated these as indicators of maturity in fetal lambs' lungs in a congenital diaphragmatic hernia (CDH) model.

METHODS

We created left CDH in 4 fetal lambs at 75 or 76days' gestation (Group A). Controls were 5 sham-operated lambs (Group B); both groups delivered at term. The right lower lung lobe (RLL) and left lower lobe (LLL) were sampled. Using histopathological image analysis, alveoli/air sacs count (AC), alveoli/air sacs area percentage (AP), average area (AA), total area (TA), and perimeter (PM) were determined. We also evaluated total lung volumes, radial alveolar count (RAC), and Type 1 alveolar epithelial cells ratio (AT1 ratio), which we previously reported. Regression analysis was performed, with p<0.05 considered significant.

RESULTS

RLL and LLL AT1 ratio and LLL RAC in Group A were lower than in Group B. There are no significant differences demonstrated by histopathological image analysis. In Group A, the AT1 ratio in the LLL was lower than in the RLL. There were no differences between LLL and RLL in Group B.

CONCLUSION

AT1 ratio was superior to the other indicators evaluating lung maturity.

Fetal surgery: a critical review

Therapeutic fetal surgical procedures are predicated upon the ability to make an accurate fetal diagnosis. The earliest open fetal surgical procedures were introduced in the 1960s to treat Rh isoimmunisation. They were introduced when it became possible to predict impending fetal demise. Open procedures were abandoned when percutaneous approaches proved superior. The introduction of fetal ultrasound allowed the diagnosis of other congenital anomalies, some being amenable to fetal interventions. Open fetal surgical procedures were initially utilised, with significant maternal morbidity. For some anomalies, percutaneous approaches became favoured. In general, all of these procedures involved significant risks to the mother, to save a baby that was likely to die before or shortly after birth without fetal intervention. Fetal repair for myelomeningocele was a "sea change" in approach. The same maternal risks were taken to improve the quality of life of the affected fetus, not save its life. The completion of the "MOMs Trial" has occasioned a "tsunami" of centres in North America applying this approach. Others are attempting percutaneous repairs, with mixed results. This paper reviews the history of fetal surgery, focusing on the themes of the tension between accurate diagnosis and prognosis and open versus "minimally invasive" approaches.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

The making of fetal surgery

Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990 s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials.

The pediatric surgeons' contribution to in utero treatment of twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate the outcome of twin-to-twin transfusion syndrome (TTTS) treated using a combination of endoscopic fetal surgery-specific techniques and surgical restraint.

SUMMARY BACKGROUND DATA

TTTS is a condition of identical twins that, if progressive and left untreated, leads to 100% mortality. The best treatment option is obliteration of the intertwin placental anastomoses, but fetal surgery carries significant maternal and fetal risks. Even if successful, percutaneous endoscopic laser ablation of placental vessels (LASER) causes premature rupture of membranes (PROM) in 10% to 20% of pregnancies. Patient selection is particularly critical because the progression of the disease is unpredictable. This has prompted many to intervene early, yielding survival rates of >=1 twin of 75% to 80%.

METHODS

We developed a minimally invasive approach to fetal surgery, a unique membrane sealing technique and a conservative algorithm that reserves intervention for severe TTTS. Pregnancies with TTTS (stages I-IV) managed in the last 8 years were reviewed. LASER was offered in stage III/IV only.

RESULTS

Ninety-eight cases of TTTS were managed in a pediatric surgery/maternal-fetal medicine collaborative Fetal Treatment Program-39 were observed (40%) and 59 underwent LASER (60%). Survival of >= twin was seen in 82.7%, and overall survival was 69.4%. These survival rates are similar to, or better than, other comparable series with similar stage distribution (low:high stage ratio 1:1) in which all patients underwent LASER. PROM rate was 4%.

CONCLUSIONS

Reserving LASER treatment for severe TTTS results in outcomes similar to, or better than, LASER for all stages. Applying fetal surgery-specific endoscopic techniques, including port-site sealing, reduces postoperative complications.

Fetal intervention: providing reasonable access to quality care

Interest in fetal intervention has become widespread in recent years. Laser therapy for the treatment of severe twin-twin transfusion alone has been the subject of more than 100 peer-reviewed articles in the past 3 years. Significant issues have arisen that affect the availability of these new therapies in the United States. Formal training fellowships have yet to be established. Questions as to the ultimate number of treatment centers that are required to provide reasonable access should be addressed. The establishment of research networks to evaluate new fetal therapies through randomized clinical trials would appear paramount to the advancement of the field.

Vitamin A deficiency (VAD), teratogenic, and surgical models of congenital diaphragmatic hernia (CDH)

Congenital diaphragmatic hernia (CDH) is a congenital malformation that occurs with a frequency of 0.08 to 0.45 per 1,000 births. Children with CDH are born with the abdominal contents herniated through the diaphragm and exhibit an associated pulmonary hypoplasia which is frequently accompanied by severe morbidity and mortality. Although the etiology of CDH is largely unknown, considerable progress has been made in understanding its molecular mechanisms through the usage of genetic, teratogenic, and surgical models. The following review focuses on the teratogenic and surgical models of CDH and the possible molecular mechanisms of nitrofen (a diphenyl ether, formerly used as an herbicide) in both induction of CDH and pulmonary hypoplasia. In addition, the mechanisms of other compounds including several anti-inflammatory agents that have been linked to CDH will be discussed. Furthermore, this review will also explore the importance of vitamin A in lung and diaphragm development and the possible mechanisms of teratogen interference in vitamin A homeostasis. Continued exploration of these models will bring forth a clearer understanding of CDH and its molecular underpinnings, which will ultimately facilitate development of therapeutic strategies.

Fetal Tracheal Occlusion for the Treatment of Congenital Diaphragmatic Hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) continues to be associated with significant mortality and morbidity rates despite advances in neonatal care. Fetal intervention for CDH has been studied for 25 years. After initial difficulties encountered with open fetal repair, attention has turned to tracheal occlusion (TO) as a method to correct pulmonary hypoplasia before birth. This article reviews our contribution to this field of research and outlines the current status of this treatment modality.

MATERIALS AND METHODS

Using the fetal lamb model, we have studied the effects of fetal TO on tracheal fluid pressure, lung growth and type II pneumocyte maturation, and surfactant production. We developed a minimally invasive and reversible technique of TO, using a detachable balloon placed using single-port tracheoscopy. We examined differential lung growth, structural maturation, pulmonary artery remodeling, and lung function during an 8-h resuscitation period in lambs, comparing normal controls, lambs with a surgically created CDH, those with CDH+TO, and those with CDH+TO and release of TO 1 week before delivery. We also studied the potential benefits of maternal betamethasone administration and the administration of surfactant at birth. Using a neonatal piglet model, we examined the effect of postnatal pulmonary distension with perfluorocarbon on lung growth. More recently, we turned to the rat nitrofen-induced CDH model to study the effects of TO on bronchial branching and some molecular markers of lung growth (Shh and LGL1).

CONCLUSIONS

Fetal TO is being used to treat human CDH, but its application remains limited by the absence of reliable and widely reproducible prenatal prognostic criteria. A better understanding of the molecular events guiding the lung growth seen with TO may help to refine its use in humans.

Lung development is not necessary for diaphragm development in mice

BACKGROUND/PURPOSE

Congenital diaphragmatic hernia affects approximately 1 in every 2000 live births. The etiology of these diaphragmatic defects is unknown. Using mice with a targeted deletion of fibroblast growth factor 10 (FGF10), which display a complete lack of lung tissue, we have examined the relationship between lung hypoplasia and diaphragmatic development.

METHODS

The diaphragms of FGF10 null mice were examined at 2 embryonic time-points and compared with their heterozygous and wild-type littermates.

RESULTS

FGF10 null mice had phenotypically normal diaphragms when compared with wild-type littermates at both time-points studied.

CONCLUSION

Normal diaphragm development appears to occur independent of lung development in mice.

Fetal surgery for congenital diaphragmatic hernia: the North American experience

The role for fetal surgery in treating fetuses with congenital diaphragmatic hernia (CDH) is unclear. Two decades of investigation have improved our understanding of the prenatal natural history, pathophysiology, and outcomes of these patients. During this same period, there have been advances in fetal surgery techniques including improvements in fetal monitoring, maternal-fetal anesthesia, tocolysis, and improved instrumentation to permit increased application of videoscopic approaches. Because of technical challenges, open fetal repair of CDH has been abandoned. Fetal tracheal ligation has shown promise, but a recently published prospective, randomized trial failed to show a benefit of fetoscopic tracheal ligation compared with expert postnatal treatment. Although there is evidence that postnatal outcomes for infants with this disease have improved with the adoption of gentilation ventilator management, high-frequency ventilation, and ECMO, there continues to be a subset of infants with severe CDH that die or suffer serious long-term morbidity despite advanced surgical care. The purpose of this article is to review issues related to prenatal diagnosis, patient selection, and outcomes for fetal surgery; and ultimately to assess whether there is a role for fetal surgery in treating fetuses with CDH.

The effect of gastroschisis on experimental diaphragmatic hernia in fetal rabbits

PURPOSE

In this study, the authors analyzed the effect of experimentally induced gastroschisis on pulmonary hypoplasia in fetal rabbits with congenital diaphragmatic hernia (CDH).

METHODS

Twenty-three pregnant rabbits underwent fetal surgery on gestational day 24 through 27. A left diaphragmatic hernia was created in 1 fetus (DH group) from each rabbit, and a left diaphragmatic hernia with gastroschisis was created in another fetus (GS group). The fetuses were delivered on gestational day 27 through 33. Histologic and morphometric examination of the lungs in each group was done.

RESULTS

In the DH group, the lungs were hypoplastic with a decrease in lung weight to body weight ratio and an increase pulmonary arterial medial wall thickness. The alveolar septae were markedly thickened with increased interstitial tissue and diminished alveolar air spaces. In the GS group, the alveolar septae were thickened but narrower than those of DH group, and air spaces were increased. The pulmonary arterial wall was markedly thickened in the DH group but only slightly thickened in the GS group.

CONCLUSIONS

Pulmonary hypoplasia seen in newborn rabbits after experimentally induced diaphragmatic hernia is less severe in those rabbits with both gastroschisis and DH.

Recent advances in fetal surgery

Fetal surgery is now an accepted modality for treatment of a variety of lethal and non-lethal congenital conditions. It represents a new, fast-moving frontier of medicine in which cooperative mulitdisciplinary effort and input are required to assure both fetal and maternal welfare. A wide range of therapeutic strategies from percutaneous to open invasive techniques has led to a complex list of different procedures for different diseases. This review identifies the most common disease entities managed by fetal intervention, examines the evolution in development of techniques to those currently used, and describes the prospective, randomized trials presently underway that are designed to establish the safety and determine true efficacy of treatment. Fetal surgery as a (multi)discipline continues to strive to minimize maternal and fetal risk. Undoubtedly, as tocolytic therapy and neonatal intensive efforts improve, fetal therapy will expand.

A randomized trial of fetal endoscopic tracheal occlusion for severe fetal congenital diaphragmatic hernia

BACKGROUND

Experimental and clinical data suggest that fetal endoscopic tracheal occlusion to induce lung growth may improve the outcome of severe congenital diaphragmatic hernia. We performed a randomized, controlled trial comparing fetal tracheal occlusion with standard postnatal care.

METHODS

Women carrying fetuses that were between 22 and 27 weeks of gestation and that had severe, left-sided congenital diaphragmatic hernia (liver herniation and a lung-to-head ratio below 1.4), with no other detectable anomalies, were randomly assigned to fetal endoscopic tracheal occlusion or standard care. The primary outcome was survival at the age of 90 days; the secondary outcomes were measures of maternal and neonatal morbidity.

RESULTS

Of 28 women who met the entry criteria, 24 agreed to randomization. Enrollment was stopped after 24 patients had been enrolled because of the unexpectedly high survival rate with standard care and the conclusion of the data safety monitoring board that further recruitment would not result in significant differences between the groups. Eight of 11 fetuses (73 percent) in the tracheal-occlusion group and 10 of 13 (77 percent) in the group that received standard care survived to 90 days of age (P=1.00). The severity of the congenital diaphragmatic hernia at randomization, as measured by the lung-to-head ratio, was inversely related to survival in both groups. Premature rupture of the membranes and preterm delivery were more common in the group receiving the intervention than in the group receiving standard care (mean [+/-SD] gestational age at delivery, 30.8+/-2.0 weeks vs. 37.0+/-1.5 weeks; P<0.001). The rates of neonatal morbidity did not differ between the groups.

CONCLUSIONS

Tracheal occlusion did not improve survival or morbidity rates in this cohort of fetuses with congenital diaphragmatic hernia.

Congenital diaphragmatic hernia: advances in prenatal therapy

Despite intensive clinical and experimental efforts, mortality from CDH remains high. More than two decades of research in multiple centers has led to a better understanding of the pathophysiology, prognosis, and treatment options for fetuses that have CDH. It now appears that fetuses that have prenatally diagnosed CDH can be stratified into high- and low-risk groups based upon sonographic parameters. Fetuses that do not have liver herniation into the chest that have a favorable LHR have an excellent chance of survival with postnatal therapy. Prenatal diagnosis allows the time and place of delivery to be planned in advance so these infants can be treated in a tertiary care nursery that has maximal medical and surgical therapy. Fetuses that have liver herniation into the chest and an unfavorable LHR have a grim prognosis. These fetuses might benefit from in utero intervention. There is no role for open fetal repair of the diaphragmatic detect; however, fetoscopic temporary tracheal occlusion might improve lung growth and development and might decrease morbidity and mortality in these infants. The FETENDO strategy appears to work, and for the first time it offers hope to the fetus that has high-risk CDH, but its efficacy must be proven in a proper randomized, controlled trial.

Effect of immediate versus slow intrauterine reduction of congenital diaphragmatic hernia on lung development in the sheep: a morphometric analysis of term pulmonary structure and maturity

The incidence of congenital diaphragmatic hernia (CDH) is 1:1,200-5, 000, and the condition is associated with high mortality and morbidity attributed principally to associated pulmonary hypoplasia. One treatment approach has been for intrauterine intervention to induce lung growth to a sufficient level to allow survival at birth. Repair of the hernia in utero has been attempted, using a method of immediate reduction and repair of the hernia (patch) compared to a slow reduction method using a silastic "silo" sewn over the diaphragm defect to contain the hernial contents. In animal studies, this second method has been associated with lower fetal morbidity and mortality. This study, utilizing the sheep model of CDH, focuses on analysis of lung structural development and maturation, comparing the efficacy of the immediate vs. slow methods of hernial repair in preventing/reversing pulmonary hypoplasia. We hypothesized that: a) Both the immediate (patch) and slow (silo) methods of hernia repair performed in the lamb model of CDH will stimulate lung growth and structural development and restore lung structure and maturity towards normal levels by term gestation; b) Effects will be detectable by morphometric measurement of the following parameters: lung volume; parenchyma to nonparenchyma tissue ratio; volume density of connective tissue in nonparenchyma; gas exchange tissue to airspace ratio; gas exchange surface area; capillary loading; alveolar/airspace density; and alveolar perimeter; c) Effects will be seen in all lobes of the lung; and d) There will be no significant difference in lung size or structural parameters between the two groups. Forty-four pregnant ewes were allocated randomly to one of four groups. Fetal lambs in three groups (n = 36) underwent CDH creation at days 72-74 of gestation. Of surviving lambs showing an adequate hernia, 9 were not operated on further, 11 underwent "repair" using a silastic chimney around the hernial contents (slow reduction), and 11 underwent "repair" by a silastic patch over the diaphragmatic defect (immediate reduction). The fourth group were normal controls. All surviving lambs (n = 8 in each group) were delivered by Cesarian section at 141-143 days (term = 145-149 days). Lungs were obtained at autopsy, inflation-fixed, divided into lobes, and sampled, and morphometric analysis was performed. Comparisons were made between these groups and with matched normal controls and CDH untreated animals prepared in conjunction and previously reported. The lungs from the CDH animals treated by both methods of fetal hernia repair showed significant lung growth and structural development and maturation, although they remained significantly hypoplastic compared to normal. There were minor differences in the lung parameters between these two groups, with a tendency for the slow method to provide more normal parameter values. An exception was the increase in lung volume that was greater for the immediate (patch) method, particularly in the left lower lobe. In conclusion, intrauterine hernia repair by both methods is capable of partially reversing total lung and lobar structural hypoplasia and immaturity. The slow reduction method, with reduced potential for mortality and morbidity, is at least as good at reversing pulmonary hypoplasia as the immediate method. Alternative intrauterine interventions to prevent or reverse pulmonary hypoplasia are discussed and compared with the hernia repair methods used in this study.

Fetal urinary tract abnormalities. Natural history, pathophysiology, and treatment

Urologic abnormalities are commonly detected on routine obstetric sonographic examinations. The progressive nature and potential reversibility of obstructive urologic anomalies have led to interest in in utero treatment of these lesions. Over 90% of obstructive urologic lesions do not need treatment until after birth. For a select group of patients, antenatal treatment may improve postnatal renal and pulmonary function. When indicated, minimally invasive nephroamniotic or vesicoamniotic stenting is the preferred method of treatment.

Correction of congenital diaphragmatic hernia in utero VII: a prospective trial

BACKGROUND

Congenital diaphragmatic hernia (CDH) remains an unsolved problem. Despite optimal postnatal care, up to 60% of CDH babies die. Experimental evidence and clinical experience have shown that in utero repair of CDH is feasible and can reverse pulmonary hypoplasia, but only in fetuses without liver herniation. For this subgroup, the safety and efficacy of repair before birth has not been compared with standard care after birth.

METHODS

Four fetuses in whom CDH without liver herniation was diagnosed underwent open fetal surgery for repair of the CDH. Seven comparison fetuses were treated conventionally. Neonatal mortality was the principle outcome variable. Secondary outcome variables included death of all causes until 2 years of age, number of days of ventilatory support, length of hospital stay, requirement for extracorporeal membrane oxygenation (ECMO), and total hospital charges.

RESULTS

There was no difference in survival between the fetal surgery group and the postnatally treated comparison group (75% v 86%). Fetal surgery patients were born more prematurely than the comparison group (32 weeks v 38 weeks' gestation). Length of ventilatory support and requirement for ECMO were equivalent in the fetal surgery group and the postnatally treated comparison group. Length of hospital stay and hospital charges did not differ between the groups.

CONCLUSIONS

Open fetal surgery is physiologically sound and technically feasible, but does not improve survival over standard postnatal treatment in the subgroup of CDH fetuses without liver herniation, primarily because overall survival in this subgroup is favorable with or without prenatal intervention. These data suggest that fetuses who have prenatally diagnosed CDH and without evidence of liver herniation should be treated postnatally.

Models of persistent pulmonary hypertension of the newborn (PPHN) and the role of cyclic guanosine monophosphate (GMP) in pulmonary vasorelaxation

At birth, a marked decrease in pulmonary vascular resistance allows the lung to establish gas exchange. Persistent pulmonary hypertension of the newborn (PPHN) occurs when this normal adaptation of gas exchange does not occur. We review animal models used to study the pathogenesis and treatment of PPHN. Both acute models, such as acute hypoxia and infusion of vasoconstrictors, and chronic models of PPHN created both before and immediately after birth are described. Inhaled nitric oxide is an important emerging therapy for PPHN. We review nitric oxide receptor mechanisms, including soluble guanylate cyclase, which produces cGMP when stimulated by nitric oxide, and phosphodiesterases, which control the intensity and duration of cGMP signal transduction. A better understanding of these mechanisms of regulation of vascular tone may lead to safer use of nitric oxide and improved clinical outcomes.

Tracheal ligation: the dark side of in utero congenital diaphragmatic hernia treatment

Currently there are two in utero procedures that have been proposed for the treatment of Congenital diaphragmatic hernia (CDH); reduction of the herniated viscera with repair of the diaphragmatic defect (CDH repair) and stimulation of lung growth by ligation of the fetal trachea (CDH + TL). Recent studies have shown that CDH + TL may result in a significant surfactant deficiency. The aim of this study was to compare the postnatal lung function of these two interventions using the fetal lamb model of CDH. CDH was created in 14 lambs at 78 days' gestation. At 110 days, seven lambs had their trachea ligated through a transverse neck incision and seven had repair of their diaphragmatic defect via a left subcostal incision. At term the lambs were instrumented with the umbilical circulation intact, then delivered and ventilated to a standard protocol for 4 hours. Pulmonary hemodynamics and blood gas levels were measured and compared every 30 minutes. Four lambs in the CDH repair group and five lambs in the CDH + TL group survived to be studied. After the initial data were analyzed, a further group of CDH + TL lambs (n = 4) were studied. In this group a replacement dose of surfactant (Infasurf, Ony Inc, Buffalo, NY) was administered. These initial results cast doubt on tracheal ligation as an in utero therapy for CDH, and indicate that the lung produced by this intervention is not physiologically normal as previously thought. However, the function of these lungs can be normalized if the surfactant deficiency is corrected. If this improvement can be maintained and there is recovery of the endogenous surfactant system, then in utero tracheal ligation may become a viable treatment for fetal CDH.

Effect of intrauterine repair of diaphragmatic hernia on the accompanying pulmonary hypoplasia in the fetal rabbit

Severe pulmonary hypoplasia precluding the sustenance of life is often found in newborns with prenatally diagnosed congenital diaphragmatic hernia (CDH). In utero repair of the hernia it is thought to be the sole method of salvaging these patients. To study the efficacy and feasibility of in utero repair of CDH, diaphragmatic hernias (DH) were produced successfully in 81 of 90 fetal rabbits by diaphragmatic perforation via a left thoracotomy at 22 days' gestation (term = 31 days). The DHs were repaired successfully in 25 of 50 fetal rabbits at 26 days' gestation. The rabbits with repaired and non-repaired DHs and their litter-mates (the control group) were delivered at 29 days' gestation by cesarean section. Some of the rabbits were killed and subjected to measurements of body and lung weight, determination of the DNA and surfactant (disaturated phosphatidylcholine; DSPC) contents of the lungs, and light and electron microscopic examination of the lung. Some newborn rabbits underwent endotracheal intubation and measurement of pressure-volume curves and pulmonary compliance. The total lung/body weight ratios and total lung DNA contents in the repair group were greater than those in the non-repair Group (P <0.01). There were no differences among the three groups in regard to body weight. When compared with the control group, both the repair and non-repair groups had increased DSPC content (P <0.01 andP <0.05, respectively), although there was no difference between the repair and non-repair groups. Histologically, the thickness of the terminal air spaces was smaller and the size of the lung acini was larger in the repair group than the non-repair group. Electron-microscopically, the number of type 11 lung cells in both the repair and nonrepair groups tended to be larger than that in the control group. When compared with the non-repair group, the repair group showed increased values for pressure-volume curves (P <0.01) and pulmonary compliance (P <0.01). In conclusion, in utero repair of CDHs is effective in improving the hypoplasticity of the lung accompanying this lesion.

Fetal surgery

Although most fetal defects are best managed after birth, a few with predictable, life-threatening developmental consequences have been successfully corrected in utero. Many technical problems have been solved, but preterm labor remains a significant risk to mother and fetus. Less invasive interventional techniques and fetal stem cell transplantation promise to extend the indications for intervention.

Experimental fetal tracheal ligation and congenital diaphragmatic hernia: a pulmonary vascular morphometric analysis

The authors have previously shown that fetal tracheal ligation (TL) reverses the pulmonary hypoplasia in experimental diaphragmatic hernia (DH) by accelerating fetal alveolar growth. The purpose of this study was to determine if growth of the accompanying macroscopic and microscopic pulmonary vasculature is also accelerated. Eighteen fetal lambs were divided into three experimental groups: diaphragmatic hernia (DH), DH and simultaneous tracheal ligation (DH/TL), and sham-operated controls (C). Animals were delivered near term, the lungs retrieved, and pulmonary capillary growth (5 to 50 microns in diameter) evaluated by standard morphometric techniques. Capillary ultrastructure was evaluated by electron microscopy. Nine additional fetal lambs of the same gestational age were equally divided into the same three groups and their lungs analyzed by pulmonary arteriography for evaluation of large vessel growth (< 100-microns diameter). Computer digital analysis of angiogram lung slices showed that the total area of large vessels was increased in DH/TL lungs when compared with DH lungs and decreased in DH lungs when compared with C lungs (P = .003); however, the ratio of large vessel area per unit of lung area was similar in all groups. Microscopic morphometry of the capillary bed showed that the total number of capillaries was increased in DH/TL lungs over both DH and C lungs (P = .0001); however, the number of capillaries per alveolus (cap/alv) was similar in all groups. In DH/TL lungs, electron microscopy showed normal capillary wall structure and normal thickness of the capillary-alveolar interface, whereas in DH lungs, capillary structure was abnormal and the capillary-alveolar interface was thickened.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal lamb pulmonary hypoplasia: pulmonary vascular and myocardial abnormalities

Neonatal pulmonary hypoplasia resulting from a congenital diaphragmatic hernia (CDH) produces hemodynamic changes and morphologic abnormalities of the pulmonary vasculature. To characterize the myocardial and pulmonary vascular status of the fetus with pulmonary hypoplasia, we studied four chronically instrumented, near-term fetal lambs with pulmonary hypoplasia, induced by producing a diaphragmatic hernia. We found an elevation in the pulmonary arterial pressure (control, 43.8 +/- 5.9 mmHg; CDH, 58.8 +/- 9.1 mmHg; p < 0.05), an elevation in the systemic arterial pressure (control, 43.8 +/- 0.48 mmHg; CDH, 58.6 +/- 6.7 mmHg; p < 0.05), and an elevation in the pulmonary vascular resistance (control, 0.47 +/- 0.11; CDH, 3.87 +/- 1.9; p < 0.05). In addition, though the total pulmonary blood flow was reduced (control, 83.5 +/- 32.9 mL/min; CDH, 22.2 +/- 17.6 mL/min; p < 0.05), the blood flow reduction was proportional to the reduction in the lung mass (control, 79.8 +/- 28.1 [in flow per 100-g lung weight]; CDH, 85.4 +/- 71.7). The increase in the pulmonary vascular resistance in relation to the unit lung mass (control, 0.55 +/- 0.33; CDH, 0.99 +/- 0.5) was not as pronounced as its increase in relation to the total pulmonary blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental fetal tracheal ligation reverses the structural and physiological effects of pulmonary hypoplasia in congenital diaphragmatic hernia

Infants with congenital diaphragmatic hernia (DH) and profound pulmonary hypoplasia are currently unsalvageable. The authors previously demonstrated that tracheal ligation (TL) accelerates fetal lung growth and reverses the pulmonary hypoplasia of fetal nephrectomy. The purpose of this study was to determine if the pulmonary hypoplasia of experimental DH could be similarly reversed and, if so, whether the resulting lungs would show better function than those of their DH counterparts. Eighteen fetal lambs were divided into three experimental groups of six animals each. In group 1, DH was created at 90 days' gestation. In group 2, DH was created at 90 days' gestation and TL performed during the same operation. Group 3 consisted of sham-operated controls. These animals were delivered near full-term, and their lungs analyzed by standard morphometric techniques. Ten additional fetal lambs were divided into two experimental groups of five animals each. In group 4, DH was created at 90 days' gestation. In group 5, DH was created at 90 days' gestation and TL performed 20 days later, at 110 days' gestation. These animals were pressure-ventilated via tracheostomy over a 2-hour period in which PaO2, PaCO2, and compliance were measured. Intratracheal pressure (ITP) was measured at the time of delivery in all groups. Upon retrieval, DH animals had abdominal viscera in the chest and small lungs; in contrast, DH/TL animals had the herniated viscera reduced from the chest by enlarged lungs. DH/TL lungs showed markedly increased growth, with significant increases in lung volume:body weight ratio (LV:BW; P = .0001), alveolar surface area (ALV.SA; P = .0001), and alveolar number (ALV#) (P = .0001) when compared with those of the DH or control group. This growth was associated with a normal maturation pattern based on histological appearance, normal airspace fraction, and normal alveolar numerical density. ITP in the DH/TL group was increased when compared with that of DH and control animals (P = .0001). Total lung DNA and protein were both elevated in the DH/TL animals (P = .0001). However, the DNA:protein ratio remained normal, suggesting lung growth had occurred through cell proliferation, not by hypertrophy. When ventilated over a range of settings, DH/TL lungs were more compliant (P = .0001) and achieved higher PaO2s (P < .003) and lower PaCO2s (P = .0001) than their DH counterparts. From these data, the authors conclude: (1) Experimental fetal DH produces hypoplastic lungs that are not capable of adequate gas exchange with conventional ventilation.(ABSTRACT TRUNCATED AT 400 WORDS)

Correction of congenital diaphragmatic hernia in utero: VI. Hard-earned lessons

Extensive experimental work suggests that repair of congenital diaphragmatic hernia (CDH) in utero may salvage severely affected fetuses who otherwise have a high expected mortality despite optimal postnatal care including extracorporeal membrane oxygenation (ECMO). We have reported that repair of CDH in utero is physiologically sound and safe for the mother, but technically difficult especially when the liver is herniated into the fetal chest. In the 3 years since our last report (1989 to 1991), 61 additional patients were referred for consideration of in utero repair. Fetal repair was attempted in 14 with severe isolated left CDH diagnosed before 24 weeks gestation. Five fetuses died intraoperatively, from technical problems related to reduction of incarcerated liver and uterine contractions--problems which have subsequently been surmounted. Nine patients were successfully repaired. Four babies survived, two delivered prematurely and died, and three died in utero within 48 hours of repair. Intraoperative technical problems have been overcome; the factors limiting successful outcome are postoperative physiologic management of the maternal-fetal unit and effective tocolysis to control preterm labor.

In utero repair of diaphragmatic hernia

This report describes the first in utero repair of diaphragmatic hernia in Australia. The patient was a 32 year old woman with major infertility problems who was diagnosed at 15 weeks gestation as having an infant with diaphragmatic hernia. After extensive consideration and counselling the parents requested in utero repair. This was performed at 28 weeks gestation and was technically successful, but the infant was found to be dead after uterine closure. The mother has subsequently been delivered of normal twins at term by Caesarean section. In utero repair of diaphragmatic hernia requires a high degree of team work, is technically demanding and has major ethical implications. It should be restricted to nationally designated units.

Intrathoracic silo for fetal diaphragmatic hernia: lung growth and slow reduction of abdominal viscera

Correction of a left congenital diaphragmatic hernia in a human fetus with a large volume of liver in the chest requires reduction of liver and viscera into the abdomen. This can kink the ductus venosus and cause the death of the fetus. Therefore, we have repaired surgically created diaphragmatic hernias in fetal lambs by leaving viscera in the chest wrapped in a silastic chimney. With fetal growth there is a relative reduction of hernia volume over weeks, potentially avoiding kinking the ductus venosus. In four groups of lambs lung size and static respiratory system compliance at birth were compared. Lambs treated by this new technique (silo, n = 7) were compared with lambs that had undergone immediate complete correction with a flat silastic patch in the diaphragm plus an abdominal patch (patch, n = 8), with lambs with uncorrected hernias (n = 6), and with normals (n = 8). There was no significant difference between total lung weights (131 +/- 6 g v 157 +/- 13 g, mean +/- SEM, silo v patch) and lung displacement volumes (142 +/- 7 mL v 162 +/- 14 mL) in either surgically corrected group. Lungs from those corrected by silo were significantly heavier than those with uncorrected herniae (131 +/- 6 g v 56 +/- 5 g, P < .01), but were not as heavy as normal lungs (131 +/- 6 g v 257 +/- 16 g, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

The CDH two-step: a dance of necessity

Repair of fetal diaphragmatic hernia has proven technically difficult especially when the left lobe of the fetal liver is incarcerated in the chest. A step-wise approach from both above and below the diaphragm solves several frustrating technical problems.

Biochemical immaturity of lungs in congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia (CDH) continue to have unacceptably high mortality rates. To better understand the associated pulmonary pathology we measured biochemical parameters of lung maturity in neonatal rats with or without congenital diaphragmatic hernia created by maternal feeding of a single dose of nitrofen on day 9.5 or day 11.5 of gestation. Lungs from neonatal rats with large CDH (n = 9, 5 right-sided, 4 left-sided) had a significantly lower lung weight (P = .0001), lung weight/body weight ratio (P = .0001), disaturated phosphatidylcholine (DSPC) per microgram DNA (P < .005), total DSPC (P = .0001), total DNA (P < .05), protein per microgram DNA (P < .05), and total protein content (P < .005) when compared with lungs from the litter mates without congenital diaphragmatic hernia (n = 10). The lungs of rats with hernia also had significantly higher DNA concentrations (P < .05) and glycogen concentrations (P < .05). These data demonstrate that lungs in neonatal rats with large CDH are biochemically immature. Treatment directed toward correcting the pulmonary biochemical immaturity of affected fetuses before birth may improve the prognosis for these babies.