Use of an Amnioport to Maintain Amniotic Fluid Volume in Fetuses with Oligohydramnios Secondary to Lower Urinary Tract Obstruction or Fetal Renal Anomalies

Prenatal Diagnoses and Intervention

Fetal upper tract urinary system dilation is one of the most common findings on prenatal ultrasonography. Rarely, this may represent fetal lower urinary tract obstruction (LUTO), of which posterior urethral valves are the predominant etiology. LUTO is the most dire fetal urologic diagnosis, as it affects not only the baby's management after birth but sometimes the course of the pregnancy itself. A variety of treatment options are available prenatally; these include observation, vesicoamniotic shunt placement, amnioinfusion, and attempts at direct treatment of the valves themselves. All fetal interventions carry substantial risks; caution should attend every discussion of treatment.

Fetal Therapy for Renal Anhydramnios

The most severe forms of congenital anomalies of the kidney and urinary tract present in fetal life with early pregnancy renal anhydramnios and are considered lethal due to pulmonary hypoplasia without fetal therapy. Due to the high rate of additional structural anomalies, genetic abnormalities, and associated syndromes, detailed anatomic survey and genetic testing are imperative when stratifying which pregnancies are appropriate for fetal intervention. Restoring amniotic fluid around the fetus is the principal goal of prenatal treatment. The ongoing multi-center Renal Anhydramnios Fetal Therapy (RAFT) trial is assessing the safety and efficacy of serial amnioinfusions to prevent pulmonary hypoplasia so that the underlying renal disease can be addressed.

Design and Protocol of the Renal Anhydramnios Fetal Therapy (RAFT) Trial

PURPOSE

Anhydramnios secondary to anuria before 22 weeks of gestational age and congenital bilateral renal agenesis before 26 weeks of gestational age are collectively referred to as early-pregnancy renal anhydramnios. Early-pregnancy renal anhydramnios occurs in at least 1 in 2000 pregnancies and is considered universally fatal when left untreated because of severe pulmonary hypoplasia precluding ex utero survival The Renal Anhydramnios Fetal Therapy (RAFT) trial is a nonrandomized, nonblinded, multicenter clinical trial designed to assess the efficacy, safety, and feasibility of amnioinfusions for patients with pregnancies complicated by early-pregnancy renal anhydramnios. The primary objective of this study is to determine the proportion of neonates surviving to successful dialysis, defined as use of a dialysis catheter for ≥14 days.

METHODS

A consortium of 9 North American Fetal Therapy Network (NAFTNet) centers was formed, and the RAFT protocol was refined in collaboration with the NAFTNet Scientific Committee. Enrollment in the trial began in April 2020. Participants may elect to receive amnioinfusions or to join the nonintervention observational expectant management group. Eligible pregnant women must be at least 18 years of age with a fetal diagnosis of isolated early-pregnancy renal anhydramnios.

FINDINGS

In addition to the primary study objective stated above, secondary objectives include (1) to assess maternal safety and feasibility of the serial amnioinfusion intervention (2) to perform an exploratory study of the natural history of untreated early pregnancy renal anhydramnios (3) to examine correlations between prenatal imaging and lung specific factors in amniotic fluid as predictive of the efficacy of serial percutaneous amnioinfusions and (4) to determine short- and long-term outcomes and quality of life in surviving neonates and families enrolled in RAFT IMPLICATIONS: The RAFT trial is the first clinical trial to investigate the efficacy, safety, and feasibility of amnioinfusions to treat the survival-limiting pulmonary hypoplasia associated with anhydramnios. Although the intervention offers an opportunity to treat a condition known to be almost universally fatal in affected neonates, the potential burdens associated with end-stage kidney disease from birth must be acknowledged.

CLINICALTRIALS

gov identifier: NCT03101891.

Novel Approach for Laparoscopically Placed Chronic Amniotic Fluid Catheters in Sheep

INTRODUCTION

Several fetal therapies involve repeated amniotic fluid intervention. We hypothesize that a minimally invasive approach can be used to safely implant an intrauterine catheter infusion system in a fetal ovine model for chronic use during pregnancy.

METHOD

Five pregnant sheep underwent operation between gestational days 110 and 115 (term 145 days). A Codman® implantable infusion pump was adapted for intrauterine use. The chamber was placed in the maternal flank and the tunneled catheter laparoscopically inserted into the amniotic cavity, secured with a pursestring. Three had an additional uterine anchoring suture. Ewes were sacrificed after natural delivery, and the uterus underwent gross and microscopic analyses.

RESULTS

There were no maternal mortalities, abortions, or preterm labor. Pumps were accessed and remained functional throughout gestation. Four ewes delivered healthy term lambs; the other delivered twins with failure to progress and demise. On necropsy, catheters secured with an anchoring suture remained in place, while the other 2 dislodged during labor. There was no chorioamnionitis by culture or histology.

CONCLUSION

Laparoscopically placed intra-amniotic infusion catheters were implanted safely and remained functional until delivery in an ovine model. This novel approach has promise in providing safe, durable amniotic fluid access for the potential treatment of fetal disease.

Fetal interventions for congenital renal anomalies

Congenital abnormalities of the kidney and urinary tract (CAKUT) represent 20% of prenatally diagnosed congenital abnormalities. Although the majority of these abnormalities do not require intervention either pre or postnatally, there is a subset of patients whose disease is so severe that it may warrant intervention prior to delivery to prevent morbidity and mortality. These cases consist of patients with moderate lower urinary tract obstruction (LUTO) in which vesicocentesis, shunting or cystoscopy are options and patients with early pregnancy renal anhydramnios (EPRA) in whom amnioinfusion therapy may be an option. The main causes of EPRA are congenital bilateral renal agenesis (CoBRA), cystic kidney disease (CKD) and severe LUTO. Untreated, EPRA is universally fatal secondary to anhydramnios induced pulmonary hypoplasia. The evidence regarding therapy for LUTO is limited and the stopped early PLUTO (Percutaneous Shunting in Lower Urinary Tract Obstruction) trial was unable to provide definitive answers about patient selection. Evidence for EPRA therapy is also scant. Serial amnioinfusions have shown promise in cases of EPRA due to CoBRA or renal failure and this treatment modality forms the basis of the ongoing NIH funded RAFT (Renal Anhydramnios Fetal Therapy) trial. At present, there is consensus that treatment for EPRA should only occur in the setting of a clinical trial.

Serial Amnioinfusion as Regenerative Therapy for Pulmonary Hypoplasia in Fetuses With Intrauterine Renal Failure or Severe Renal Anomalies: Systematic Review and Future Perspectives

The aim of this study was to investigate the effect of serial amnioinfusion therapy (SAT) for pulmonary hypoplasia in lower urinary tract obstruction (LUTO) or congenital renal anomalies (CRAs), introduce patient selection criteria, and present a case of SAT in bilateral renal agenesis. We conducted a search of the MEDLINE, EMBASE, Web of Science, and Scopus databases for articles published from database inception to November 10, 2017. Eight studies with 17 patients (7 LUTO, 8 CRA, and 2 LUTO + CRA) were included in the study. The median age of the mothers was 31 years (N=9; interquartile range [IQR], 29-33.5 years), the number of amnioinfusions was 7 (N=17; IQR, 4.5-21), gestational age at first amnioinfusion was 23 weeks and 4 days (N=17; IQR, 21-24.07), gestational age at delivery was 32 weeks and 2 days (N=17; IQR, 30 weeks to 35 weeks and 6.5 days), birthweight of newborns was 3.7 kg (N= 9; IQR, 2.7-3.7 kg), Apgar score at 1 minute was 2.5 (N=8; IQR, 1-6.5), and Apgar score at 5 minutes was 5.5 (N=8; IQR, 0-7.75). In conclusion, SAT may provide fetal pulmonary palliation by reducing the risk of newborn pulmonary compromise secondary to oligohydramnios. Multidisciplinary research efforts are required to further inform treatment and counseling guidelines. We propose a multidisciplinary approach to prenatal classification of fetuses with LUTO to inform patient selection.

Contemporary Outcomes of Patients with Isolated Bilateral Renal Agenesis with and without Fetal Intervention

INTRODUCTION

Bilateral renal agenesis (BRA) is a lethal diagnosis, specifically meaning that natural survival beyond birth is not expected secondary to pulmonary hypoplasia. Limited contemporary data are available about intervention and the impact of restoring amniotic fluid volume in relation to the risk for lethal pulmonary hypoplasia and other factors that might influence survival in cases of fetal BRA.

OBJECTIVE

We report the largest series of patients undergoing fetal intervention and postnatal care for BRA at a single comprehensive fetal center.

METHODS

All patients with fetal BRA were reviewed from January 2004 to November 2017. Maternal and neonatal data were collected in an institutional review board-approved retrospective review.

RESULTS

From 2014 to 2017, 20 singleton pregnancies with isolated fetal BRA were evaluated and 14 had amnioinfusion. Eight had serial infusions. Of those, there were 6 neonatal deaths. There were 2 neonatal survivors beyond 30 days; however, both died of sepsis on dialysis. One of these survivors received amnioinfusions by percutaneous approach and one via amnioport. There were no survivors to transplantation.

CONCLUSION

Fetal intervention via amnioinfusion may promote pulmonary survivorship after birth, but postnatal survival remains poor. Future studies must place an emphasis on standardizing the postnatal approach to this patient population.

Etiology and management of early pregnancy renal anhydramnios: Is there a place for serial amnioinfusions?

Early pregnancy renal anhydramios (EPRA) comprises congenital renal disease that results in fetal anhydramnios by 22 weeks of gestation. It occurs in over 1 in 2000 pregnancies and affects 1500 families in the US annually. EPRA was historically considered universally fatal due to associated pulmonary hypoplasia and neonatal respiratory failure. There are several etiologies of fetal renal failure that result in EPRA including bilateral renal agenesis, cystic kidney disease, and lower urinary tract obstruction. Appropriate sonographic evaluation is required to arrive at the appropriate urogenital diagnosis and to identify additional anomalies that allude to a specific genetic diagnosis. Genetic evaluation variably includes karyotype, microarray, targeted gene testing, panels, or whole exome sequencing depending on presentation. Patients receiving a fetal diagnosis of EPRA should be offered management options of pregnancy termination or perinatal palliative care, with the option of serial amnioinfusion therapy offered on a research basis. Preliminary data from case reports demonstrate an association between serial amnioinfusion therapy and short-term postnatal survival of EPRA, with excellent respiratory function in the neonatal period. A multicenter trial, the renal anhydramnios fetal therapy (RAFT) trial, is underway. We sought to review the initial diagnosis ultrasound findings, genetic etiologies, and current management options for EPRA.

Anhydramnios in the Setting of Renal Malformations: The National Institutes of Health Workshop Summary

Anhydramnios in the setting of severe malformations of the fetal kidney and urinary tract is associated with a high incidence of stillbirths and life-threatening complications, including severe pulmonary hypoplasia, umbilical cord compression, and perinatal asphyxia. To prevent such adverse outcomes, some centers in the United States and elsewhere are offering amniotic fluid restoration for women diagnosed with anhydramnios in the setting of fetal renal malformations. The procedures include infusions of amniotic fluid substitutes (normal saline), percutaneously or through an amnioport-an implanted system for serial or continuous infusion of normal saline to maintain the desired amniotic fluid volume. The procedures are intended to prevent pulmonary hypoplasia and allow the pregnancy to progress closer to term gestation, enabling postnatal renal management, including long-term dialysis and renal transplantation. However, these procedures have not been recommended as standard of care by the professional societies because there are many knowledge gaps, including few data on short-term and long-term renal outcomes. The available diagnostic methods do not provide reliable prognostic information, and the current maternal and fetal interventions have not been standardized. To address these unresolved issues and to propose a research agenda, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institute of Diabetes and Digestive and Kidney Diseases invited a panel of experts to a workshop in August 2016. This report provides a summary of that meeting.

Uncovering new physiology in bilateral renal agenesis following amnioinfusion

Background

Bilateral renal agenesis has uniformly been a lethal diagnosis in the perinatal or neonatal period. With the advent of more advanced renal replacement therapy as a bridge to renal transplantation, amnioinfusion has been explored at our center as a way to prevent lethal pulmonary hypoplasia secondary to oligohydramnios.

Case presentation

We describe two cases of bilateral renal agenesis with serial amnioinfusion during pregnancy. The families opted for full neonatal intervention and post-natal renal support. While lethal pulmonary hypoplasia was avoided, early and refractory hypotension limited the ability to perform dialysis in these neonates.

Conclusions

Our limited experience shows that barriers to care such as lethal respiratory failure and technical limitations of early dialysis are not the only barriers prohibiting care for this population.

Amnioinfusions to Treat Early Onset Anhydramnios Caused by Renal Anomalies: Background and Rationale for the Renal Anhydramnios Fetal Therapy Trial

Anhydramnios caused by early anuria is thought to be universally fatal due to pulmonary hypoplasia. Bilateral renal agenesis and early fetal renal failure leading to anhydramnios constitute early pregnancy renal anhydramnios (EPRA). There have been successful reports of amnioinfusions to promote lung growth in the setting of EPRA. Some of these successfully treated EPRA fetuses have survived the neonatal period, undergone successful dialysis, and subsequently received a kidney transplant. Conversely, there are no reports of untreated EPRA survivors. This early success of amnioinfusions to treat EPRA justifies a rigorous prospective trial. The objective of this study is to provide a review of what is known about fetal therapy for EPRA and describe the Renal Anhydramnios Fetal Therapy trial. We review the epidemiology, pathophysiology, and genetics of EPRA. Furthermore, we have performed systematic review of case reports of treated EPRA. We describe the ethical framework, logistical challenges, and rationale for the current single center (NCT03101891) and planned multicenter trial.

Early transplantation into a vesicostomy: a safe approach for managing patients with severe obstructive lesions who are not candidates for bladder augmentation

INTRODUCTION

Management of severe antenatally detected oligohydramnios with and without obstruction is improving with the result that more fetuses are surviving with early renal failure. Significant advances have occurred in all specialties involved in the management of these patients. All these specialties working together have resulted in the survival of more patients born with renal failure.

OBJECTIVE

The aim of this study is to highlight the medical advances in antenatal management of fetal oligohydramnios and pulmonary hypoplasia and to demonstrate that transplantation into a diverted urinary system is safe and leads to good outcomes.

STUDY DESIGN

A case series of five patients were presented who, at the study center's respective facilities, recently underwent renal transplantation into bladders drained by cutaneous vesicostomy after extensive bladder evaluation and whose clinical cases highlight the aim of this study.

RESULTS

A total of 5 patients were reviewed. Renal failure was caused by posterior urethral valves in four patients, and in one patient Eagle-Barrett syndrome. One patient received an amnio-infusion and attempted antenatal bladder shunt. One patient was ventilator dependent until 24 months, and required a tracheostomy, while two patients were ventilator dependent for the first few months of life. Three of five patients were dialysis dependent. Patient age at transplantation ranged from 20 to 61 months. All patients were poorly compliant pre-transplant and had bladder capacities ranging from 10 mL to 72 mL. Months since follow-up ranged from 3 to 64 months. Creatinine levels prior to transplant ranged from 1.9 to 5.6. During the follow up period, this range decreased to 0.13 to 0.53. Two of five patients had UTI episodes since transplantation. Patient A showed Banff Type 1A acute T-cell mediated rejected approximately two months after transplant, but subsequent biopsies have been negative for rejection. Patient A also required a vesicostomy revision approximately two months after transplant and balloon dilation of UVJ anastomosis three months after transplant.

DISCUSSION

Vesicostomy is an especially attractive option to manage children with small bladders to accommodate the high urinary output that occurs after transplantation in infants who require an adult kidney. Recent advances in antenatal management such as amnioinfusion for oligohydramnios have made significant impacts in pulmonary and renal management of this patient population over recent years.

CONCLUSION

This report provides further support for the use of vesicostomy as an option for surgical management of patients with renal failure with oligohydramnios and severe obstructive lesions identified antenatally. It also indicates the need to update the criteria for antenatal management of oligohydramnios in obstructive and anephric patients.

Ethical Considerations Concerning Amnioinfusions for Treating Fetal Bilateral Renal Agenesis

Congenital bilateral renal agenesis has been considered a uniformly fatal condition. However, the report of using serial amnioinfusions followed by the live birth in 2012 and ongoing survival of a child with bilateral renal agenesis has generated hope, but also considerable controversy over an array of complex clinical and ethical concerns. To assess the ethical concerns associated with using serial amnioinfusions for bilateral renal agenesis, we assembled a multidisciplinary group to map the ethical issues relevant to this novel intervention. The key ethical issues identified were related to 1) potential risks and benefits, 2) clinical care compared with innovation compared with research, 3) counseling of expectant parents, 4) consent, 5) outcome measures, 6) access and justice, 7) conflicts of interest, 8) effects on clinicians, 9) effects on institutions, and 10) long-term societal implications. These ethical issues should be addressed in conjunction with systematic efforts to examine whether this intervention is safe and effective. Future work should capture the experiences of expectant parents, women who undergo serial amnioinfusions, those born with bilateral renal agenesis and their families as well as clinicians confronted with making difficult choices related to it.

Advances in paediatric urology

Paediatric urological surgery is often required for managing congenital and acquired disorders of the genitourinary system. In this Series paper, we highlight advances in the surgical management of six paediatric urological disorders. The management of vesicoureteral reflux is evolving, with advocacy ranging from a less interventional assessment and antimicrobial prophylaxis to surgery including endoscopic injection of a bulking agent and minimally invasive ureteric reimplantation. Evidence supports early orchidopexy to improve fertility and reduce malignancy in boys with undescended testes. A variety of surgical techniques have been developed for hypospadias, with excellent outcomes for distal but not proximal hypospadias. Pelvi-ureteric junction obstruction is mostly detected prenatally; indications for surgery have been refined with evidence, and minimally invasive pyeloplasty is now standard. The outlook for patients with neurogenic bladder has been transformed by a combination of clean intermittent catheterisation, algorithms of diagnostic investigations, and innovative medical and surgical therapies. Posterior urethral valves are associated with considerable mortality; fetal diagnosis allows stratification of candidates for intervention, but ongoing bladder dysfunction in patients after valve ablation remains a cause of long-term morbidity.