FETAL CARE AND NEONATOLOGY
FETAL CARE AND NEONATOLOGY
LIVING POTENTIAL
UNDER PRESSURES
HOW 3D PRINTING HELPS TREAT SPINA
BIFIDA’S MOST SEVERE CASES
HOW FETAL SURGEONS FIX A LIFE-THREATENING CONGENITAL
ANOMALY WITH A VERY SMALL BALLOON
At three or four weeks, before
the mother likely even knows
she’s pregnant, the tiny spine and
backbone of the human embryo
are beginning to form. They form in
tandem, one within the other.
In the womb, the fetus holds its
breath. This is how the lungs grow:
fluid naturally builds up in the lungs,
creating pressure and forcing them
to expand. When the pressure is
great enough, the baby exhales.
Myelomeningocele (MMC), a
common form of spina bifida,
occurs when a section of the neural
tube that runs along the spine
fails to close, leaving the spinal
cord exposed. The consequences
are severe: contact with amniotic
fluid causes nerve damage, loss
of sensation, sometimes paralysis.
Drainage of cerebral fluid through
the lesion causes the brain to sit
lower than it should, blocking the
flow of cerebral fluid altogether and
resulting in hydrocephalus — water
on the brain. This not-so-rare birth
defect is diagnosed in one in every
1,000 babies born.
Twenty years ago, about 80 percent
of babies born with MMC needed a
cerebral shunt to aid drainage.
“These children are subject to
innumerable operations for shunt
malfunctions and infections, for
lower extremity procedures, bladder
and bowel dysfunction,” says fetal
surgeon Timothy Crombleholme,
M.D., Surgeon-in-Chief and Director
of the Colorado Fetal Care Center
at Children’s Hospital Colorado.
TIMOTHY
CROMBLEHOLME, M.D.
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Research found long ago that
repairing MMC with a patch in utero
could improve outcomes vastly:
prenatal repairs reduced shunting by
50 percent. For years, the operation
involved opening the mother’s
womb, measuring the opening in
the neural tube, creating a patch
to cover the aperture and, finally,
Patches prefabricated with 3D printing to mend
myelomeningoceles, or openings, in a fetus's
spinal architecture
applying the patch — a lengthy and
arduous process.
Last year, fetal surgeons at
Children’s Colorado became the
first in the world to use 3D printing
to prefabricate MMC patches in
advance of surgery, based on 3D
computer models assembled from
fetal MRI. Prefabrication reduces the
length of the procedure to a fraction
of what it was before, significantly
increasing precision and minimizing
risk. These 3D models have since
become regular tools in the Fetal
Care Center’s continuing efforts
to give children with MMC a better
quality of life.
The potential of 3D printing has
hardly been tapped. Within a
couple of years, Dr. Crombleholme
predicts, the technology will be able
to print a ‘living patch’ using the
fetus’s own cells.
“In theory, you can harvest
amniocytes — fetal cells suspended
in the amniotic fluid — to grow
stem cells derived from them in
culture and use them to ‘seed’ a
patch: so called ‘4D’ printing. The
patch becomes incorporated into
the baby’s own tissues,” says Dr.
Crombleholme. “The range of what
we can contemplate doing is really
going to expand.”
“We figured this out,” says fetal
surgeon Kenneth Liechty, M.D.,
Co-Director of the Colorado Fetal
Care Center at Children’s Hospital
Colorado, “because we noted
babies with a blockage of the airway
before birth have really huge lungs.”
The opposite is true for babies with
congenital diaphragmatic hernia
(CDH), essentially a large hole in the
diaphragm. Without a barrier to keep
them in place, abdominal organs
float up into the chest and crowd the
lungs, stunting their growth.
“These are some of the sickest
babies we care for,” Dr. Liechty says.
“It’s not just the size of the lungs, it’s
the size of the vessels, too. When
blood can’t get out from the heart
through the lungs, it finds another
way around. What you have then is
the heart pumping blue blood to the
rest of the body.”
Doctors wondered: if you blocked
a fetus’s trachea, would the buildup
of fluid offset the pressure of the
abdominal organs and result in lung
growth? “Initially the procedure
opened up the mother’s uterus, then
opened up the fetus’s neck and put
a clip on the trachea,” Dr. Liechty
says. “We saw some improvement,
but there was high morbidity.”
Aside from extreme risk and
invasiveness, the problem was
that a complete blockage prevents
the development of surfactant,
a protein that opens the lungs’
internal airways, resulting in babies
unable to breathe.
The solution to both problems:
a very small balloon.
The process, called fetoscopic
tracheal balloon occlusion (FETO),
begins with a three-millimeter skin
incision at 27 to 29 weeks gestation.
The Fetal Care Center’s surgery
team inserts the deflated balloon,
about the size of a grain of rice, into
the mother’s uterus at the end of
a fetoscope, and guides it into the
fetus’s mouth, down its throat and
into the trachea, and then blows it
up. At 34 weeks, the team pops the
balloon and pulls it out. A window
of even 24 hours before birth
can be enough time for sufficient
surfactant to build up.
KENNETH
LIECTHY, M.D.
Currently under FDA investigational
device exemption, which allows
unapproved technologies to
be used for testing, the
approach is extremely
new. “We’re one of
“We’re one of
just a few sites in
the United States
just a few sites in
capable of doing
the United States
this, and we’re the
capable of doing
only one that’s
actually done it,”
this, and we’re
Dr. Liechty says.
the only one
And although it’s too
that’s actually
soon for outcomes
data, two cases so
done it.”
far have both produced
good lung growth.
“The national survival rate for this
condition is about 62 per 6V