But let’s focus for now on
Basically, there are –
We start with hemolysis.
These red blood cells are breaking down.
And this can be from ABO incompatibility
between the mother and the child.
It could be from Rh incompatibility
between the mother and the child
or it could be from some
Those are usually a bit more mild.
Let’s start with Rh incompatibility.
Here we have a couple that
have decided to have a child.
The mother is Rh negative.
She does not express this
protein on her red blood cells.
The father is Rh positive.
They decided to have
their first baby.
Now this baby seems to have accidentally,
just by luck, just got dad’s proteins.
So the baby has Rh
positive red blood cells.
But remember the baby is inside
the mother who does not.
During the course of our first pregnancy,
a little bit of that baby’s blood, just
a tiny amount gets out into the mother.
She, her immune system, sees these Rh
positive red blood cells and says,
“This isn’t me" and she
that will now be sticking to these
Rh positive red blood cells.
Now, the second baby comes along.
She’s had her first baby,
everything went great.
Now, they’re having
their second baby
and amazingly enough, just
by freak of chance alone,
this child also inherited
dad’s Rh protein.
Now, the baby is expressing
Rh positive red blood cells.
Mom has antibodies formed against
Rh positive red blood cells
already from the last pregnancy.
These antibodies are floating
around in small number.
But remember, antibodies
can be transplacental.
When the baby is born,
cross over into the baby
and now, the baby has a problem with mom’s
antibodies attacking the baby’s blood.
This results in a hemolysis
and it can be quite severe.
Basically, we can prevent this from happening
because we can easily test mom’s blood.
And one of the standard tests we do in moms
is understanding whether they’re
Rh positive or Rh negative.
If they’re Rh negative, there’s not
really anything we have to be doing here
except we have to treat to prevent
this child from getting in trouble.
But if they’re Rh positive, there’s
really nothing we have to do.
This mom’s not going to mount
antibodies against here own Rh.
So let’s look at the
Rh negative mother.
We’re going to prevent newborn hemolysis
by giving here anti-Rh antibodies.
What’s going to happen is these are
going to bind to any Rh positive cells
from the baby that actually
sneak into her circulation
and will prevent her from making
her own Rh positive antibodies.
These sites will all be taken up by the
RhoGAM or Rh-positive gammaglobulin
that we’ve given this
patient, the mother, already.
We give this typically
at 28 weeks gestation.
And again, three days after
delivery to block any another
that came across during the
delivery for the next child.
Additionally, patients may have
red blood cell membrane defects.
These cells are more fragile
and can break down and cause
Or patients may have glucose-6-phosphate
dehydrogenase deficiency or G6PD
Those infants may have oxidative stress,
resulting in unconjugated
Patients may have pyruvate
which can cause red blood cell
breakdown or a hemoglobinopathy
such as thallasemia or sickle cell,
which may cause increased
red blood cell breakdown.
Really anything that causes the cells to
break down can cause unconjugated hyperbili.
Additionally, patients may
not have an increased
fragility or autoimmune attack
on their red blood cells,
but they may just be sick.
Patients with sepsis
have red cell breakdown.
Patients in DIC may
Also, there can be blood collections outside
the blood vessel that then break down.
For example, a very bad cephalohematoma.
There can be a lot of blood in
there and as that breaks down,
it’s resorbed into the
body as bilirubin.
Infants of diabetic mothers
may have polycythemia
and those infants are at greater risk
for unconjugated hyperbilirubinemia.
Also, metabOlic problems are associated
with this such as hyperthyroidism.
Crigler-Najjar is an inability to clear the
unconjugated hyperbili through the liver,
so is Gilbert syndrome.
So both of those patients,
although it’s a liver disease,
which we usually think of as
causing conjugated hyperbili,
those two in particular can
be an unconjugated hyperbili.
Galactosemia is classic for this, also
don’t forget about the cataracts,
but that can cause a conjugated hyperbilirubinemia
also because of the liver damage.
So it can actually cause both.
Also, hereditary tyrosinemia can
cause an unconjugated hyperbili.