Introducing the Amnioport: A Unique Approach to Amnioinfusions

The amnioinfusion procedure — injecting fluid into the amniotic sac surrounding a fetus — has been around since the ‘80s. It’s a lifesaver for many fetal conditions: For example, with the support of infusions every few days, a baby with fetal renal failure can develop and survive in utero.

But in 2010, there was just one way to go about it: a needle stick for every infusion. Unfortunately, every needle stick carried a risk of rupture of membranes: A rupture of the bag of waters was the most common complication.

In other words, Dr. Crombleholme and his team worried that each and every needle stick risked breaking the mother’s water early.

“I began thinking about how we could address this,” says Dr. Crombleholme, who directs Connecticut Children’s Fetal Care Center, “and came up with the amnioport.”
 

The idea itself was simple: a port under the skin like the kind used for chemotherapy, connected to the amniotic sac via a tiny catheter tube. Set it up once, and a care team could easily do as many infusions as needed through the port — no more needle sticks. That should reduce the risk of the mother’s water breaking early (the scientific term: preterm premature rupture of membranes, or PPROM).

Positioning the device was trickier. Where to locate the port? How to keep the mini catheter in place even through uterine contractions?

“It took some tinkering,” says Dr. Crombleholme.

Ultimately, he decided to place the port on mom’s lower left chest, easily accessible and braced by the ribcage. To secure the catheter, he landed on a series of surgical techniques with names like the Witzel tunnel and double purse-string sutures — delicate maneuvers, performed on the tiniest scale.

Today across the U.S., only a handful of fetal surgery teams can pull this off, including Connecticut Children’s. Almost all have been personally trained by Dr. Crombleholme.

 

Amnioport versus needle-stick amnioinfusions

There are a few key differences between needle-based amnioinfusion — which is still common across the U.S. — and the more specialized amnioport approach.

Reliability

• Needle-based: If the level of amniotic fluid drops too low between sessions, a needle-stick infusion becomes much more challenging at best, and impossible at worst.
• Amnioport: Infusion is easy at any level of amniotic fluid.

Precision

• Needle-based: Often, to leave as much time as possible between potentially risky needle sticks, a team slightly over-infuses the amniotic sac. However, this can further stress the membranes.
• Amnioport: Since frequency is not a concern, infusions can take place every few days, and the team can infuse the amniotic sac to a normal level each time.

Risk of procedure-related PPROM (preterm premature rupture of membranes)

• Needle-based: Every time a needle punctures the amniotic sac, there is a risk of rupturing the membranes. 
• Amnioport: The risk of rupture occurs just once, at the initial surgery to place the device.

Complicated pregnancies

• Needle-based: If PPROM occurs, needle-stick infusions are no longer possible.
• Amnioport: Even with ruptured membranes, infusions can continue as usual.
  
   

It’s been about 15 years since Dr. Crombleholme developed the amnioport. The results have been rewarding, to say the least. Pregnancies that need amnioinfusion now have an alternative approach..

“The data suggests that the rate of PPROM is lower with the amnioport — and if PPROM occurs, the gestational age is later,” says Dr. Crombleholme. He and his team are currently assembling evidence to share with the scientific community.

In the meantime, the amnioport is a ray of hope for moms and babies who need amnioinfusions.

“The more effective the amnioinfusions and the longer you can continue them, the better outcome these babies have,” says Dr. Crombleholme.