Renal Anhydramnios Fetal Therapy

Amniotic fluid is critical for normal lung development. After the first trimester of pregnancy amniotic fluid is composed nearly completely of fetal urine. The absence of amniotic fluid due to lack of urine production by the fetal kidneys is known as anhydramnios. Early pregnancy renal anhydramnios or EPRA is thought to be 100% lethal after birth if left untreated because of neonatal respiratory failure. The two causes of EPRA are bilateral renal agenesis or fetal renal failure (such as from multicystic dysplastic kidneys or obstructed kidneys). Recently there have been clinical case reports of repeated or serial infusions of isotonic fluid (amnioinfusions) into the amniotic cavity leading to respiratory survival in neonates with a history of EPRA. Some surviving neonates have gone on to undergo successful dialysis and kidney transplant as toddlers. However, no prospective trial has investigated the safety of amnioinfusions in EPRA, the feasibility of doing serial amnioinfusions in EPRA pregnancies without causing rupture of membranes, or the neonatal survival rate after serial amnioinfusions for EPRA. Accordingly the goal of the Renal Anhydramnios Fetal Therapy (RAFT) trial is to determine the safety, feasibility, and efficacy of serial amnioinfusions to promote normal fetal lung development in EPRA. Pregnant patients presenting to a RAFT center with a diagnosis of EPRA will undergo an evaluation including diagnostic amnioinfusion with ultrasound imaging to verify the diagnosis. Counseling by a team of subspecialists including a maternal fetal medicine doctor, a pediatric nephrologist, a pediatric surgeon, a neonatologist, a kidney transplant specialist, a genetic counselor and a social worker will be given to every patient. This counseling is meant to provide the clearest picture possible of what serial amnioinfusions entail and what life will be like for a surviving neonate with no kidney function. Survivors will require urgent dialysis with a peritoneal or hemodialysis catheter. These children are prone to significant infections and often need a gastrostomy tube in order to receive sufficient nutrition. The goal is for these children to ultimately undergo the most robust form of renal replacement therapy with a kidney transplant once they are large enough to tolerate it.

Once the diagnosis of EPRA is confirmed, counseling is complete and a patient is deemed eligible for serial amnioinfusions, enrollment into the study will be offered. Patients may choose to enroll in the study, may choose to continue the pregnancy and not be a part of the study or may choose to terminate the pregnancy. If the patients elect to enroll in the study, they will be given a further choice of intervention with serial amnioinfusions or expectant management with repeat imaging. Participants will not be randomized because there is no realistic hope that expectant management will lead to postnatal survival. Patients who do not choose to undergo amnioinfusions but who also do not elect to terminate will provide invaluable insight into the in utero natural history of EPRA if they enroll in the trial. The sample size of this trial is based on a calculation of the number of patients required to adequately determine a postnatal survival rate of amnioinfusions for EPRA with narrow confidence intervals. Postnatal survival will be defined as survival for >=14 days and placement of dialysis access; this is the primary outcome measure. We have determined that 35 maternal/fetal participants are required in order to calculate a survival rate of anywhere from 20-80%. We plan to study two 35 participant cohorts of EPRA patients, those with EPRA from bilateral renal agenesis and those with EPRA from fetal renal failure. We will therefore aim for a total of 70 maternal/fetal pairs with EPRA to undergo serial amnioinfusions. Additionally we will aim to recruit 30 maternal/fetal pairs with EPRA in the expectant management group for a total of 100 participants.

During the prenatal portion of the trial we plan to collect a small specimen of amniotic fluid from participants in the amnioinfusion group during each amnioinfusion. This fluid will be assayed for different protein and lipid measures of lung maturity at a research lab at Johns Hopkins. Additionally, in both the amnioinfusion group and the expectant management group we will study ultrasound, MRI and echocardiogram measures of lung growth. We will correlate these biochemical and radiologic markers with survival in order to better understand who is likely to respond to amnioinfusions and why that response is occurring. We also plan to study several secondary and tertiary outcomes in our surviving EPRA patients. These outcomes include survival to discharge from a RAFT center, survival to transplant and quality of life measures for both participants and their families.

The changes made to the outcomes are due to the protocol amendment.

Update: Due to recommendations from the RAFT trial Data and Safety Monitoring Board, the trial is no longer open to enrollment for pregnancies complicated by bilateral renal agenesis as of July 19, 2022. Enrollment for patients with pregnancies complicated by other causes of fetal renal failure remains open.

Inclusion criteria

• Confirmed anhydramnios before 22 weeks gestational age (GA) for patients with fetal renal failure (excluding bilateral renal agenesis)
• Consent is signed and first therapeutic amnioinfusion can and does occur before 26 weeks and 0 days GA
• Confirmation that the expectant mother does not wish to undergo termination of the pregnancy
• Age ≥ 18 years of age for expectant mothers
• Willingness to be followed and deliver at a RAFT center
• Willingness for postnatal care to be performed at a RAFT center until discharge
• Completed consults with Pediatric Nephrology, Neonatology, Transplant Surgery, Pediatric surgery, Maternal-Fetal Medicine Specialist, and Licensed Clinical Social Worker and a Genetic Counselor

Exclusion criteria

• Cervix less than 2.5 cm in length
• No significant pathogenic or likely significant pathogenic findings on Karyotype or Microarray
• Other significant congenital anomalies in the fetus
• Evidence of chorioamnionitis or abruptio placentae
• Evidence of rupture of membranes or chorioamniotic separation
• Evidence of preterm labor
• Multiple gestation
• Severe maternal medical condition in pregnancy.
• Maternal depression as assessed by a Beck Depression Inventory score equal to or greater than 17 that is refractory to treatment
• Technical limitations precluding amnioinfusion