0:00

This is an MRI of the abdomen and pelvis in

0:02

a patient presenting at 28 weeks gestation

0:05

referred from the maternal-fetal medicine

0:07

clinic after abnormal obstetric ultrasound

0:10

with concern for placenta accreta spectrum.

0:13

Again, we've placed our steady-state free

0:15

precession images on the left and our

0:17

turbo spin echo images on the right.

0:20

As we scroll inferiorly, we begin to

0:22

see the gravid uterus come into view.

0:24

We can see T2 heterogeneous myometrium

0:28

in its entirety surrounding the gestational sac.

0:32

As we scroll inferiorly, the

0:34

placenta begins to come into view.

0:36

We can see direct abutment of the myometrium

0:39

by the placenta here with a relatively normal

0:42

overlying appearance of the myometrium.

0:46

As we scroll more inferiorly, we can see that

0:48

the bulk of the placenta is low-lying and is

0:51

along the left lateral aspect of the uterus.

0:54

We also begin to see classic features

0:57

of placenta accreta spectrum.

0:59

Large placental bands and engorged abnormal

1:03

vasculature within the placenta at this level.

1:08

When we try to follow the myometrium

1:10

overlying the placenta, we can see

1:13

that it's relatively easy to identify

1:15

the muscular layer more superiorly.

1:17

But as we scroll inferiorly, we begin to lose

1:21

the uterine myometrium overlying the placenta.

1:24

And as we near the level of the cervix and

1:26

upper vagina, there's a mass of placental

1:29

tissue with little to no intervening myometrium.

1:33

Particularly inferiorly within the pelvis, as we

1:36

have this mass of placental tissue in the region

1:39

of the upper vagina, I'd like to point out the

1:41

number of asymmetric and engorged blood vessels

1:45

in the left hemipelvis that are

1:47

extending toward the placental mass.

1:50

We'll revisit this in a moment.

1:53

These are coronal T2-weighted

1:54

images of the same patient.

1:57

Again, we can see a low-lying,

1:59

left-sided placenta with features

2:01

of placenta accreta spectrum.

2:03

The placenta has an abnormal, rounded contour.

2:06

It's thickened in multiple

2:08

locations without smooth tapering.

2:10

We see large aberrant placental vessels,

2:13

placental heterogeneity, and placental bands.

2:15

In addition to marked thinning and

2:17

absence of the myometrium inferiorly.

2:22

Again, within the left hemipelvis, we can

2:25

see multiple dilated blood vessels, which

2:28

course toward the cervix and upper vagina.

2:32

These are the sagittal T2-weighted images

2:34

of the abdomen and pelvis for this patient.

2:37

We can see that like many of the patients

2:39

with placenta accreta spectrum, this patient

2:40

also has complete placenta previa, with the

2:43

placenta covering the internal os of the cervix.

2:47

The placental bands

2:49

and aberrant placental vessels are evident

2:53

on the turbo spin echo sequences for this

2:56

patient and are much more apparent than they

2:59

are on the steady state precession images.

3:02

An important distinguishing feature when

3:05

you're trying to determine if something

3:07

is a placental band rather than a vessel,

3:09

is if it's dark on both sequences, you

3:12

can confirm that it's a placental band

3:14

rather than an engorged blood vessel.

3:16

If it's dark on the turbo spin

3:18

echo sequences only, you can favor

3:21

an engorged placental vessel.

3:25

Now, let's revisit the axial

3:27

images for this patient.

3:29

I'd like to again focus on the

3:31

blood vessels that seem to

3:33

be recruited in the pelvis here.

3:35

As we mentioned in the region of the cervix

3:37

and upper vagina, this patient has a focal

3:40

placental mass without intervening myometrium

3:43

and extensive engorgement of the left greater

3:45

than right pelvic sidewall vasculature.

3:48

When we reported this case, we raised suspicion

3:51

for placenta percreta, but in addition to

3:54

this, we also said that there was likely

3:57

recruitment of the cervical vaginal plexus,

3:59

particularly on the left, and that further

4:01

evaluation with angiography was warranted.