- [Voiceover] One of the most annoying things ever
has to be when you're putting on a screen protector
on a phone and you notice a bubble in it.
You guys know what I'm talking about.
It happens to pretty much all of us.
There is this bubble where the screen protector
isn't touching the screen of the phone
and so the screen protector can't do its job.
It turns out this is really similar
to what a placental abruption is.
So, you've got the uterus and there's
the fetus inside the uterus, and there's a placenta
which, remember, is this pool of blood
that has the oxygen and the nutrients
that the fetus needs to grow and thrive.
And the pool of blood is supplied by uterine arteries,
which are juicy and plump during pregnancy.
Now there aren't only three arteries
and they aren't really this big
but this is drawn this way for simplification.
So what I've tried to show with this diagram
is that the placenta is really nicely
sealed to the wall of the uterus,
and that's essential for the placenta to do its job.
But what can happen sometimes for a variety
of different reasons is that these
uterine arteries here can tear, they can actually rupture,
and the blood that's inside them
will flow out and start to build up
between the uterus and the placenta, like this.
So this is kind of like that screen protector bubble
that we were talking about earlier.
And at this point where the placenta
isn't attached to the uterus anymore,
the placenta isn't receiving the oxygenated
and the nutrient-rich blood anymore
so it can't do its job of turning it around
and providing it to the fetus.
So it turns out that this accumulation of blood
can stay small, it can stay limited.
Or the bleeding can continue and the pressure
from that blood can dissect through
or it can tear through the seal
between the placenta and the wall of the uterus,
causing the placenta to separate
from the wall of the uterus.
And with that, some of the blood can leak
through the vagina, which is usually
how this condition is noticed.
The mom will have some vaginal bleeding.
Now, before we go any further let's talk
a little bit about about some nomenclature.
So, when there's only a little accumulation
of blood and it's hidden behind the placenta
it's called the concealed abruption.
And, as you can imagine, you don't get any vaginal bleeding
with a concealed abruption, right?
It's pretty much trapped behind,
the blood is trapped behind the placenta.
But when the blood has torn through the entire seal
and the placenta is completely separated from the uterus
it's called a complete abruption.
So, getting back to some of the symptoms
of abruption, the first is vaginal bleeding.
Vaginal bleeding that occurs late
in the course of the pregnancy,
specifically after the 20-week mark,
and that's referred to as antepartum,
as antepartum bleeding.
And there are two main causes of antepartum bleeding.
One is placenta previa, which presents
with painless antepartum bleeding.
And the second is placental abruption,
which presents with painful, very painful
antepartum bleeding because, as you can probably imagine,
the placenta shearing apart from the wall
of the uterus to which it was pretty tightly attached
is a painful process.
Now, in addition to painful vaginal bleeding,
the mom, the patient, also experiences uterine contractions.
And to understand why this occurs,
why you experience uterine contractions,
you have to understand that the uterus
is first and foremost a muscle,
and in this situation where blood is leaking
from the uterine arteries, the uterus tries
to control the bleeding by doing what it knows best
and that is to contract.
And the goal of these contractions
is to squeeze down on these arteries that pass
through the wall of the uterus
to limit the amount of blood flowing through them.
And while that's a pretty effective way
of controlling the bleeding,
it also has an unwanted side effect
of sometimes pushing out the baby.
That is to say that these uterine contractions
can sometimes lead to premature labor.
And while we're talking about the symptoms
of placental abruption, let's not forget
what happens to the baby.
With the placenta being separated from it's blood supply,
the fetus isn't receiving the oxygen that it needs,
so the fetus can become asphyxiated,
and it can show with concerning heart tracings.
So, usually that's referred to as
nonreassuring fetal heart tracing,
which is abbreviated this way.
And usually, this constellation of symptoms
is how placental abruption presents.
And it's really important to know and
to understand these symptoms,
and it's because the diagnosis of placental abruption
is primarily a clinical diagnosis.
So sure, you can try to image the uterus
and the placenta but during pregnancy
you're pretty much restricted to the use of ultrasound
because of the concern for harming the fetus
with other imaging modalities.
And on ultrasound, blood, especially fresh blood,
and the placenta have a very similar appearance.
So that can make it difficult to diagnose
an abruption with ultrasound.
That's not to say that it can't be done,
just that it can be difficult at times.
Now, in the case that you do make a diagnosis
of abruption, deciding what the next step is
can be pretty complicated.
On one extreme end of the spectrum,
where mom and baby are both unstable,
delivery is usually the answer.
Delivery is also usually chosen if
the baby is past 34, 36 weeks
and is healthy enough to survive outside the uterus.
On the other end of the spectrum,
if the abruption is really minor
and both mom and baby are looking good
and the baby is too young to survie
outside the womb alone, we can usually monitor
both mom and baby until delivery is a safe option.
So, after having discussed all those features of abruption,
let's consider some of the causes of abruption.
Remember that the end point of all these causes
has to be the tearing or the rupture of the uterine arteries
that's the ultimate cause of placental abruption.
So, the one cause that always jumps out to me is trauma.
I always remember trauma, and I try to do
this animation thing to show how trauma causes abruption.
So, if a pregnant woman is in a car accident
or any traumatic event really,
the uterus stays fixed, it doesn't move,
because after all, it's attached to your skeleton,
it's attached to other organs.
But, that's not the case for the placenta and the baby.
So any trauma or any mechanical event
can cause the placenta to shear away,
to stretch and rupture these uterine arteries,
which leads to bleeding and abruption.
Now, as much as I tend to remember trauma
as being the main cause of abruption,
and you probably will too,
trauma turns out to be a pretty uncommon cause.
Most abruptions are actually due to chronic processes,
long-term processes, that affect how blood vessels
form early on in the course of the pregnancy.
So causes such as hypertension or high blood pressure,
smoking or cocaine use, these conditions
cause diseased blood vessels to form.
Blood vessels that are fragile,
that are easily broken, right?
That can lead to placental abruption.
So, in a nutshell, that is placental abruption.