00:01
Let's discuss placental abnormalities.
00:04
Before we discuss what's abnormal, let's
discuss what normal placenta looks like.
00:09
When we talk about the anatomy of
normal placenta, we notice the placenta disc
and that's divided into the basil plate,
which is the maternal side of the placenta,
and the chorionic plate - that's the fetal
side of the placenta as you can see here.
00:22
We have the membranes and then
we have a three-vessel umbilical cord.
00:25
Now, unlike the other structures in the human body,
this three-vessel cord has two arteries and one vein.
00:33
Now let's talk about some of the
placental structural abnormalities.
00:37
First, let's talk about a succenturiate lobe.
00:41
So this abnormality is one in which an
extra lobe separates from the placenta.
00:47
The clinical manifestation of this can be postpartum hemorrhage.
00:51
At times that extra lobe can separate and when you're
delivering the placenta, that extra lobe does not come out,
and it can be a cause of postpartum
hemorrhage because of retained products.
01:03
Next, let's talk about a velamentous insertion.
01:07
So with the velamentous insertion, the umbilical
vessels traverse the membranes as you can see here.
01:14
The vessels are easily compressible
and so that's the clinical manifestation.
01:19
Also, it can be associated with placenta previa.
01:24
Vasa previa.
01:27
So with vasa previa, the vessels traverse the cervical os.
01:30
So you can see here in the picture, that
the vessels are in front of the fetal head.
01:35
Now that can be problematic.
01:36
If those vessels are lacerated during a
cervical exam, or artificial rupture of membranes,
the baby can exsanguinate.
01:43
So it's important to know if the patient
has a vasa previa prior to delivery.
01:50
Let's go through a question about abnormal placentation.
01:53
A patient is known to have a velamentous
insertion, what is the most likely fetal abnormality
to be seen on fetal heart rate tracing while in labor?
A. Late decelerations, B. Recurrent variable decelerations,
C. End stage bradycardia or D. recurrent accelerations
Well, the answer is recurrent variable decelerations.
02:15
Remember those vessels are easily compressed
and when we have compression of vessels,
that causes recurrent variable decelerations.
02:25
Now that we've talked about abnormal placental
structure, now let's talk about abnormal placenta location.
02:32
So we have placenta previa, placenta
accreta, placenta increta, or placenta percreta.
02:39
Let's start with placenta previa.
02:41
So this is a situation in which the placenta
is located near or over the cervical os.
02:48
If disrupted in pregnancy, it can cause
significant antepartum hemorrhage.
02:52
It can actually cause death of the baby.
02:55
And C-section is usually the recommended route of delivery.
02:58
You can imagine if the placenta is covering the
cervix, then the fetus is not able to come through that
through the cervical os.
03:06
Now, placenta accreta.
03:09
So with placenta accreta, the placental
trophoblast invade to the myometrium.
03:15
On histology,
we noticed an absence of Nitabuch’s layer
, that's how we diagnose it.
03:21
It can be associated with placenta previa,
and the placenta can be very
difficult to remove at the time of delivery,
that can make this a cause of postpartum
hemorrhage because of retained products of conception.
03:35
Now increta, placenta increta is a condition in which
the placenta trophoblast invade through the myometrium.
03:43
Remember, accreta was just to the myometrium,
now we're talking about through the myometrium.
03:49
It can also be associated with
placenta previa, just as accreta can,
and the placenta is usually very adherent during
delivery and this can be a cause of postpartum hemorrhage.
03:59
Usually, C-section with hysterectomy is the management
option, because we're unable to physically remove the placenta
so the whole uterus has to be removed.
04:10
Now percreta.
04:13
In placenta percreta, the placental
trophoblast are through the serosa.
04:17
So remember with accreta, we were 'to' the
myometrium, with increta, we were 'through' the myometrium
and percreta, we are completely through
the myometrium and through the serosa,
so now we're going outside of the uterus.
04:30
The placental tissue can be in various places outside
of the uterus, most commonly the bladder or the rectum,
and this causes severe hemorrhage at the time of delivery.
04:40
Because of this, we don't try to remove the placenta.
04:43
And you can imagine, we can't remove the
placenta if it's into the bladder, or if it's to the rectum.
04:48
And so a lot of times we do C-section with
hysterectomy, and we leave some of the placenta in situ.
04:53
Again, we can't remove it from the
bladder or the rectum if it has invaded that far.
05:00
So let's talk about another question.
05:03
What ultrasound finding is seen in placenta accreta?
Is it A. lambda sign?
Is it B. absence of Nitabuch's layer?
C. the double peak sign or
D. a Tri laminar layer?
Do you remember this from the lecture?
That's right, the answer
is B - absence of Nitabuch's layer.