Experimental treatment of bilateral fetal chylothorax using in-utero pleurodesis

Outcome and etiology of fetal pleural effusion, fetal ascites and hydrops fetalis after fetal intervention: retrospective observational cohort from a single institution

OBJECTIVES

Non-immune hydrops fetalis (NIHF) is the pathological accumulation of fluids in fetal compartments, without maternal isoimmunization. Fetal interventions (e.g. shunting, fetal paracentesis, fetal thoracocentesis, fetal pleurodesis) are used to alleviate fluid accumulations, but the outcome is uncertain because the underlying causes of NIHF vary. We aimed to explore the etiology and long-term outcome of NIHF after fetal intervention.

METHODS

This was a retrospective review of fetuses with NIHF, defined by the presence of fetal ascites, pleural or pericardial effusion, skin edema or cystic hygroma, or a combination of these features, who underwent intervention at our institution during the period 2012-2021. Clinical surveillance, genetic analysis and viral infection screening were used to define the etiology. Chart reviews and telephone interviews were conducted to assess the long-term outcomes.

RESULTS

In total, 55 fetuses were enrolled and 46 cases had final follow-up data after delivery. Etiology was identified in 33 cases, including four for which the underlying causes were not identified initially using small-gene-panel tests but which were later diagnosed with monogenic disorders by whole-exome sequencing (WES). Twenty-three cases with follow-up survived, having a follow-up period of 2-11 years at the time of writing, of which 17 were healthy. All 11 cases initially presenting as congenital chylothorax survived with favorable outcome.

CONCLUSIONS

The etiologies of NIHF are heterogeneous, and the long-term (spanning 2-11 years) outcome of fetal intervention varies, according to the underlying etiology, with cases caused by congenital chylothorax having the best prognosis. Genome-wide tests, such as WES, may be helpful in determining the underlying condition in cases caused by a genetic disorder, and this may affect fetal therapy approaches in the future. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Syndromic and single gene disorders associated with fetal pleural effusion (I): Noonan syndrome, RASopathy and congenital lymphatic anomalies

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides an overview of syndromic and single gene disorders associated with fetal pleural effusion that is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Chromosomal abnormalities associated with fetal pleural effusion (I): General overview

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides an overview of chromosomal abnormalities associated with fetal pleural effusion which is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Chromosomal abnormalities associated with fetal pleural effusion (II): Specific and non-specific chromosome aberrations

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides a comprehensive view of specific and non-specific chromosome aberrations associated with fetal pleural effusion which is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Diagnostic yield from prenatal exome sequencing for non-immune hydrops fetalis: A systematic review and meta-analysis

Non-immune hydrops fetalis (NIHF) has multiple genetic etiologies diagnosable by exome sequencing (ES). We evaluated the yield of prenatal ES for NIHF, and the contribution of additional clinical findings and history. Systematic review was performed with PROSPERO tag 232951 using CINAHL, PubMed, and Ovid MEDLINE from January 1, 2000 through December 1, 2021. Selected studies performed ES to augment standard prenatal diagnostic approaches. Cases meeting a strict NIHF phenotype were tabulated with structured data imputed from papers or requested from authors. Genetic variants and diagnostic outcomes were harmonized across studies using current ACMG and ClinGen variant classification guidelines. Thirty-one studies reporting 445 NIHF cases had a 37% (95% CI: 32%-41%) diagnostic rate. There was no significant difference between isolated NIHF and NIHF with fetal malformations or between recurrent and simplex cases. Diagnostic rate was higher for consanguineous than non-consanguineous cases. Disease categories included RASopathies (24%), neuromuscular (21%), metabolic (17%), lymphatic (13%), other syndromes (9%), cardiovascular (5%), hematologic (2%), skeletal (2%), and other categories (7%). Inheritance patterns included recessive (55%), dominant (41%), and X-linked (4%). ES should be considered in the diagnostic workup of NIHF with and without associated ultrasound findings regardless of history of recurrence or consanguinity.

Survival of Hydrops Fetalis with and without Fetal Intervention

Objectives: To investigate the survival rate of hydrops fetalis after fetal interventions and neonatal intensive care. Methods: We reviewed the medical records of patients diagnosed with hydrops fetalis from January 2009 to December 2019 at Changhua Christian Children’s Hospital. All cases had abnormal fluid accumulation in at least two body compartments during pre- and postnatal examination. The primary outcome measure was the mortality rate. We also collected information regarding disease etiology, duration of hospital stay, Apgar score, gestational age at birth, initial hydrops fetalis diagnosis, fetal intervention, first albumin and pH levels, and maternal history. Results: Of the 42 cases enrolled, 30 survived and 12 died; the mortality rate was 28.6%. Furthermore, 22 cases received fetal intervention, while 20 cases did not; there was no significant difference in their survival rates (75% and 68%, respectively). Survival rate was associated with gestational age at birth, initial diagnosis time, birthweight, Apgar score, initial albumin and pH levels, and gestational hypertension. Only one case was immune-mediated. Among the nonimmune-mediated cases, the three most common etiologies were lymphatic dysplasia (12/42), idiopathic disorders (10/42), and cardiovascular disorders (5/42). Conclusions: Overall, hydrops fetalis was diagnosed early, and fetal intervention was performed in a timely manner. Preterm births were more frequent, and birthweight was lower in the cases that underwent fetal intervention than in those that did not, but there was no significant between-group difference in mortality. The initial diagnosis time, gestational age at birth, birthweight, Apgar score, and first albumin and pH levels were independently associated with mortality.

Fetal hydrops and the Incremental yield of Next-generation sequencing over standard prenatal Diagnostic testing (FIND) study: prospective cohort study and meta-analysis

OBJECTIVE

To determine the incremental yield of exome sequencing (ES) over chromosomal microarray analysis (CMA) or karyotyping in prenatally diagnosed non-immune hydrops fetalis (NIHF).

METHODS

A prospective cohort study (comprising an extended group of the Prenatal Assessment of Genomes and Exomes (PAGE) study) was performed which included 28 cases of prenatally diagnosed NIHF undergoing trio ES following negative CMA or karyotyping. These cases were combined with data from a systematic review of the literature. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched electronically (January 2000 to October 2020) for studies reporting on the incremental yield of ES over CMA or karyotyping in fetuses with prenatally detected NIHF. Inclusion criteria for the systematic review were: (i) at least two cases of NIHF undergoing sequencing; (ii) testing initiated based on prenatal ultrasound-based phenotype; and (iii) negative CMA or karyotyping result. The incremental diagnostic yield of ES was assessed in: (i) all cases of NIHF; (ii) isolated NIHF; (iii) NIHF associated with an additional fetal structural anomaly; and (iv) NIHF according to severity (i.e. two vs three or more cavities affected).

RESULTS

In the extended PAGE study cohort, the additional diagnostic yield of ES over CMA or karyotyping was 25.0% (7/28) in all NIHF cases, 21.4% (3/14) in those with isolated NIHF and 28.6% (4/14) in those with non-isolated NIHF. In the meta-analysis, the pooled incremental yield based on 21 studies (306 cases) was 29% (95% CI, 24-34%; P < 0.00001; I²  = 0%) in all NIHF, 21% (95% CI, 13-30%; P < 0.00001; I²  = 0%) in isolated NIHF and 39% (95% CI, 30-49%; P < 0.00001; I²  = 1%) in NIHF associated with an additional fetal structural anomaly. In the latter group, congenital limb contractures were the most prevalent additional structural anomaly associated with a causative pathogenic variant, occurring in 17.3% (19/110) of cases. The incremental yield did not differ significantly according to hydrops severity. The most common genetic disorders identified were RASopathies, occurring in 30.3% (27/89) of cases with a causative pathogenic variant, most frequently due to a PTPN11 variant (44.4%; 12/27). The predominant inheritance pattern in causative pathogenic variants was autosomal dominant in monoallelic disease genes (57.3%; 51/89), with most being de novo (86.3%; 44/51).

CONCLUSIONS

Use of prenatal next-generation sequencing in both isolated and non-isolated NIHF should be considered in the development of clinical pathways. Given the wide range of potential syndromic diagnoses and heterogeneity in the prenatal phenotype of NIHF, exome or whole-genome sequencing may prove to be a more appropriate testing approach than a targeted gene panel testing strategy. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Congenital Chylothorax of the Newborn: A Systematic Analysis of Published Cases between 1990 and 2018

BACKGROUND

Congenital chylothorax (CCT) of the newborn is a rare entity but the most common cause of pleural effusion in this age-group. We aimed to find the optimal treatment strategy.

MATERIAL AND METHODS

A PubMed search was performed according to the PRISMA criteria. All cases were analyzed according to prenatal, perinatal, and postnatal treatment modalities and follow-ups.

RESULTS

We identified 753 cases from 157 studies published between 1990 and 2018. The all-cause mortality rate was 28%. Prematurity was present in 71%, male gender dominated 57%, mean gestational age was 34 weeks, and birth weight was 2,654 g. Seventy-nine percent of newborns had bilateral CCT, the most common associated congenital anomalies with CCT were pulmonary lymphangiectasia and pulmonary hypoplasia, and the most common chromosomal aberrations were Down, Noonan, and Turner syndromes, respectively. Mechanical ventilation was reported in 381 cases for mean 17 (range 1-120) days; pleural punctuations and drainages were performed in 32% and 64%, respectively. Forty-four percent received total parenteral nutrition (TPN) for mean 21 days, 46% medium-chain triglyceride (MCT) diet for mean 37 days, 20% octreotide, and 3% somatostatin; chemical pleurodesis was performed in 116 cases, and surgery was reported in 48 cases with a success rate of 69%. In 462 cases (68%), complete restitution was reported; in 34 of 44 cases (77%), intrauterine intervention was carried out.

CONCLUSION

Respiratory support, pleural drainages, TPN, and MCT diet as octreotide remain to be the cornerstones of CCT management. Pleurodesis with OK-432 done prenatally and povidone-iodine postnatally might be discussed for use in life-threatening CCT.

A system-based approach to the genetic etiologies of non-immune hydrops fetalis

A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.

Fetal primary pleural effusions: Prenatal diagnosis and management

Fetal pleural effusions can be associated with significant perinatal morbidity and mortality. When diagnosed antenatally, referral to a tertiary fetal medicine center is recommended for a detailed ultrasound evaluation for additional structural abnormalities or features suggestive of congenital infections or fetal anemia. The effusions should be characterized as unilateral or bilateral, and presence of hydrops and/or mediastinal shift should be documented. Additional testing should include fetal echocardiography, maternal testing for blood group and screen, hemoglobinopathies, and congenital infections. Invasive genetic testing is recommended with infectious testing on amniotic or pleural fluid. Pleuroamniotic shunting is recommended for large primary pleural effusions with significant mediastinal shift or hydrops, as several large series have demonstrated improvement in perinatal survival, particularly in hydropic fetuses. Delivery should occur in a tertiary care center with neonatal expertise, and infants should be followed up long-term for respiratory and neurodevelopmental outcomes.

Cystic Hygroma: A Preliminary Genetic Study and a Short Review from the Literature

BACKGROUND

The objective of this study is to examine the hypothesis that cystic hygroma (CH) with normal karyotype can manifest as a Mendelian inherited trait, and that a genetic similitude with hereditary lymphedema exists. To reach this goal, we investigated the prevalence of genetic variants in angiogenesis and lymphangiogenesis genes in a cohort of euploid fetuses with CH that almost resolved before delivery. A short review of cases from literature is also reported.

METHODS AND RESULTS

Five fetuses were screened using a next-generation sequencing approach by targeting 33 genes known to be associated with vascular and lymphatic malformations. The genetic evaluation revealed two novel variants in KDR and KRIT1 genes.

CONCLUSION

A review of the literature to date revealed that an association exists between CH and hereditary lymphedema and, similar to lymphedema, CH can be inherited in autosomal recessive and autosomal dominant manner, with the latter most likely associated with a better prognosis. About KDR and KRIT1 genes, no other similar associations are reported in the literature and caution is needed in their interpretation. In conclusion, we thought that a genetic test for the outcome of familial CH could be of enormous prognostic value.

Prenatal Therapy Improves the Survival of Premature Infants with Congenital Chylothorax

BACKGROUND

Chylothorax is a rare condition among neonates, although it is considered clinically significant, as it is difficult to manage in these patients. In addition, the course of chylothorax varies widely. Therefore, we aimed to elucidate the clinical features and effect of prenatal therapy on the prognosis of congenital chylothorax in neonates.

METHODS

We retrospectively reviewed the medical records of all infants with congenital chylothorax who were admitted to National Taiwan University Hospital, Taipei, Taiwan between January 2000 and December 2012. Their demographic characteristics, as well as their antenatal, perinatal, and postnatal information, were collected for our analysis of the mortality risk.

RESULTS

We found 29 infants who were diagnosed with congenital chylothorax during the study period. The median gestational age at birth was 34 weeks (range, 28-41 weeks), and 71% of the infants presented with hydrops fetalis. Most cases of congenital chylothorax were bilateral (bilateral: 86.2%, unilateral: 13.79%), and the overall survival rate was 59.6%. Among the cases with a prenatal diagnosis at ≤ 34 weeks of gestation, infants who received prenatal therapy had a significantly higher survival rate, compared to infants who did not receive prenatal therapy (76.9% vs. 11%, respectively; p = 0.008).

CONCLUSION

We found that infants whose chylothorax was diagnosed ≤ 34 weeks of gestation, and who subsequently received prenatal therapy, experienced a better perinatal condition and exhibited improved postnatal outcomes.

Treatment of Primary Fetal Hydrothorax with OK-432 (Picibanil): Outcome in 14 Fetuses and a Review of the Literature

Background: Primary fetal hydrothorax (PFHT) is an uncommon condition with an estimated prevalence of 1 in 10,000/15,000 pregnancies. Therapeutic interventions include thoracocentesis, thoraco-amniotic shunting (TAS), and pleurodesis using OK-432. Methods: A review of the literature was performed to identify all cases of PFHT treated with TAS and OK-432. All cases of PFHT referred to the Fetal Maternal Unit at Royal Prince Alfred Hospital between 2002 and 2012 were retrospectively reviewed. In the cohort of fetuses treated with OK-432, the main perinatal outcomes evaluated were termination of pregnancy, live birth, neonatal death, and fetal death in utero. Secondary outcomes included gestational age (GA) at diagnosis, GA at treatment, GA at resolution, birth weight, and GA at birth. The development of the children was screened using the Ages and Stages Questionnaires, Version 3 (ASQ-3, 2009). Results: Primary hydrothorax was diagnosed in 31 fetuses, of which 14 had treatment with OK-432. One pregnancy terminated after treatment with OK-432. Survival was 85% (11/13): 100% in fetuses treated with OK-432 without hydrops, and 78% in those treated with hydrops. This compares well to the cases of TAS in the literature with an average survival of 63%: 85% in fetuses without hydrops and 55% with hydrops. The mean GA at birth was 36+4 weeks and mean birth weight 3,007 g. Eight of the 9 children screened with ASQ-3 scored well within the normal range. Conclusion: OK-432 appears to be a valid treatment option in fetuses with PFHT, particularly in those diagnosed at early GAs.

Fetal surgery: principles, indications, and evidence

Since the first human fetal surgery was reported in 1965, several different fetal surgical procedures have been developed and perfected, resulting in significantly improved outcomes for many fetuses. The currently accepted list of fetal conditions for which antenatal surgery is considered include lower urinary tract obstruction, twin-twin transfusion syndrome, myelomeningocele, congenital diaphragmatic hernia, neck masses occluding the trachea, and tumors such as congenital cystic adenomatoid malformation or sacrococcygeal teratoma when associated with developing fetal hydrops. Until recently, it has been difficult to determine the true benefits of several fetal surgeries because outcomes were reported as uncontrolled case series. However, several prospective randomized trials have been attempted and others are ongoing, supporting a more evidence-based approach to antenatal intervention. Problems that have yet to be completely overcome include the inability to identify ideal fetal candidates for antenatal intervention, to determine the optimal timing of intervention, and to prevent preterm birth after fetal surgery. Confronting a fetal abnormality raises unique and complex issues for the family. For this reason, in addition to a maternal-fetal medicine specialist experienced in prenatal diagnosis, a pediatric surgeon, an experienced operating room team including a knowledgeable anesthesiologist, and a neonatologist, the family considering fetal surgery should have access to psychosocial support and a bioethicist.

Chylothorax and chylous ascites: management and pitfalls

Leakage of lymph from the lymphatic ducts causes chylothorax (CT) or chylous ascitis (CA). This may happen for unknown reasons during fetal life or after birth and may also be caused by trauma after thoracic surgery or by other conditions. Fetal CT and CA may be lethal particularly in cases with fetal hydrops that sometimes benefit of intra-uterine instrumentation. After birth, symptoms are related to the amount of accumulated fluid. Sometimes, severe cardio-respiratory compromise prompts active therapy. Most patients with CT or CA benefit from observation, rest, and supportive measures alone. Drainage of the fluid may be necessary, but then loss of protein, fat, and lymphoid cells introduce new risks and require careful replacement. Low-fat diets with MCT and parenteral nutrition decrease fluid production while allowing adequate nutritional input. If lymph leakage does not stop, secretion inhibitors like somatostatin or octreotide are prescribed, although there is only weak evidence of their benefits. Imaging of the lymphatic system is indicated when the leaks persist, but this is technically demanding in children. Shunting of the lymph from one body space to another by means of valved catheters, embolization of the thoracic duct, and/or ligation of the major lymphatics may occasionally be indicated in cases refractory to all other treatments.

Genetics of lymphatic anomalies

Lymphatic anomalies include a variety of developmental and/or functional defects affecting the lymphatic vessels: sporadic and familial forms of primary lymphedema, secondary lymphedema, chylothorax and chylous ascites, lymphatic malformations, and overgrowth syndromes with a lymphatic component. Germline mutations have been identified in at least 20 genes that encode proteins acting around VEGFR-3 signaling but also downstream of other tyrosine kinase receptors. These mutations exert their effects via the RAS/MAPK and the PI3K/AKT pathways and explain more than a quarter of the incidence of primary lymphedema, mostly of inherited forms. More common forms may also result from multigenic effects or post-zygotic mutations. Most of the corresponding murine knockouts are homozygous lethal, while heterozygotes are healthy, which suggests differences in human and murine physiology and the influence of other factors.

Genome-wide gene expression analysis implicates the immune response and lymphangiogenesis in the pathogenesis of fetal chylothorax

Fetal chylothorax (FC) is a rare condition characterized by lymphocyte-rich pleural effusion. Although its pathogenesis remains elusive, it may involve inflammation, since there are increased concentrations of proinflammatory mediators in pleural fluids. Only a few hereditary lymphedema-associated gene loci, e.g. VEGFR3, ITGA9 and PTPN11, were detected in human fetuses with this condition; these cases had a poorer prognosis, due to defective lymphangiogenesis. In the present study, genome-wide gene expression analysis was conducted, comparing pleural and ascitic fluids in three hydropic fetuses, one with and two without the ITGA9 mutation. One fetus (the index case), from a dizygotic pregnancy (the cotwin was unaffected), received antenatal OK-432 pleurodesis and survived beyond the neonatal stage, despite having the ITGA9 mutation. Genes and pathways involved in the immune response were universally up-regulated in fetal pleural fluids compared to those in ascitic fluids. Furthermore, genes involved in the lymphangiogenesis pathway were down-regulated in fetal pleural fluids (compared to ascitic fluid), but following OK-432 pleurodesis, they were up-regulated. Expression of ITGA9 was concordant with overall trends of lymphangiogenesis. In conclusion, we inferred that both the immune response and lymphangiogenesis were implicated in the pathogenesis of fetal chylothorax. Furthermore, genome-wide gene expression microarray analysis may facilitate personalized medicine by selecting the most appropriate treatment, according to the specific circumstances of the patient, for this rare, but heterogeneous disease.