How Amnioinfusion via Amnioport Improves Postnatal Pulmonary Survivorship for Babies with Fetal Renal Failure

A fetal renal failure diagnosis is historically fatal because the lungs do not develop due to lack of amniotic fluid. New research from physicians at Cincinnati Children’s Fetal Care Center is changing the paradigm of care for these babies in utero and after birth.

Mounira Habli, MD, Fetal Care Center maternal-fetal medicine director, presented her oral abstract “Outcome of Pregnancies Complicated by Fetal Renal Failure (FRF) Treated by Percutaneous Needle Amnioinfusions versus Amnioport,” and Stefanie Riddle, MD, Fetal Care Center neonatal director, presented her oral poster “Serial Percutaneous Amnioinfusion for Pulmonary Palliation and Neonatal Survival in Fetal Renal Failure” at this year’s Society for Maternal Fetal Medicine’s annual pregnancy meeting, held virtually Jan. 31 to Feb. 5, 2022.

Cincinnati Children’s was proud to be a major participant.

“For this diagnosis and anything that leads to end-stage kidney disease, postnatal work has historically been considered futile,” says Riddle. “We are trying to change that approach.”

The novel study completed by Habli and Riddle compares the use of percutaneous needle (PN) amnioinfusion and subcutaneous amnioport (SA) infusion to maintain amniotic fluid.

The kidneys help make amniotic fluid, which is fetal urine. Amniotic fluid cycles through their lungs, helping them to develop. When there is too little amniotic fluid, pulmonary hypoplasia occurs.

The study found that “SA allowed for maintenance of amniotic fluid volume over a longer duration, which may contribute to a higher rate of postnatal pulmonary survival and subsequent survival to renal replacement therapy.”

That’s a dramatic shift. SA artificially assists in development of the lungs so that a baby can survive outside the womb. SA and PN do not improve kidney function. Babies with improved lung function still need immediate dialysis at birth and until they are old enough for a kidney transplant, at around age 2.

Amnioinfusion: Needle Versus Port

Percutaneous needle amnioinfusion and subcutaneous amnioport infusion both provide fluid to the uterus.

With PN:

• Each needle stick and infusion is a new procedure.
• Interrupting the uterine membranes can cause complications such as contractions or membrane rupture.
• Most FRF pregnancies require 10 to 12 infusions over the course of the pregnancy.
• The level of amniotic fluid in the womb fluctuates.

With SA:

• Mom undergoes surgery to implant a port over the ribs that is connected to the uterus.
• Fluid can be delivered through the port to the amniotic sac daily or at appropriate intervals.
• Unlike PN, SA only disturbs the uterus once.
• SA helps maintain a constant level of amniotic fluid.

The amnioport is an innovative technique that helps maintain amniotic fluid for pregnancy duration to improve lung development, Habli says.

“We need to study this disease further to know what other treatments might be needed for earlier in a pregnancy,” says Habli.

Protocols and Results

Inclusion criteria for the study included:

• Early pregnancy renal anhydramios diagnosis at less than 25 weeks
• Mother older than 18
• Normal fetal karyotype
• Singleton pregnancy

Among the pregnant women who met the inclusion criteria, 21 underwent SA and 65 received PN. All participants and their partners received extensive counseling before choosing to take part in the study.

“We give them the whole picture,” Habli explains. “What it means to do the infusions, what it means for baby to do dialysis and transplant, and what they’ll need after transplant.”

While both methods saw complications, SA patients had better outcomes. SA patients also showed higher survival rates at 24 hours and seven days than PN patients.

Those who underwent amnioinfusion showed:

• 65% survival at 24 hours
• 76% pulmonary survival
• 60% survival to neonatal intensive care unit (NICU) discharge
• 73% of NICU survivors have received or were undergoing work-up for renal transplantation

Notably, these results included patients that survived and did not require dialysis after delivery with adequate urine output and renal function.

Ongoing Survival

“Long-term infant survival after FRF is still a challenge,” Habli says. Comprehensive teams are needed to care for these babies, including experts in neonatal care, nephrology, palliative care, transplant and urology. “We have to be able to bridge them to transplant,” Riddle says. “It’s a hugely challenging pathway, but we have shown survival to transplant is possible.”

Dialysis technology for infants is greatly improved. But many complications can arise with dialysis and pulmonary function.

SA provides a better than 50/50 shot at survival for babies with fetal renal failure, Riddle says.

“But there’s still a lot of doubt or disbelief and a lack of clarity as to whether this is the right thing to do,” says Riddle.

More Study Needed

Improvements are needed in dialysis and neonatal care, as well as in understanding the natural history of this disease, Habli says.

Other key takeaways:

• Serial percutaneous amnioinfusion increased pulmonary survival but is associated with complications and preterm birth.
• Despite these complications, survival to neonatal dialysis and NICU discharge is possible with fetal interventions.
• Survival to discharge and ultimately renal transplantation remain challenging due to ongoing difficulties with chronic dialysis and prolonged hospitalization.
• Further studies aimed at decreasing complications and addressing optimal method of serial amnioinfusions are needed.