0:00

Our next scan in a trauma is an active bleed, and this is

0:04

really where CT is one of the workhorses and the most

0:08

commonly performed exam in an emergency setting.

0:13

Either post-intervention or trauma,

0:16

dropping hematocrit, looking for active bleed remains a

0:19

significant acute reason of why someone would get imaging,

0:25

why that scan would be expedited, and why that read would be expedited.

0:28

So in this person,

0:30

starting at the back, you can see that there is a large amount of collection

0:34

in the right retroperitoneal region. It's all hyperdense.

0:38

This is all a right retroperitoneal hematoma.

0:42

You can see that the density is high, it's 80.

0:45

It extends all the way into the pelvis right here

0:49

in that paravesicular region. These are all artifacts

0:53

from contrast within the urinary bladder

0:56

that can cause some streak artifacts and beam hardening artifacts in the pelvis.

1:01

You can see that this was the site that the intervention was, in the form of

1:05

fat stranding.

1:07

There's a little convexity here. That's typically what it looks like when

1:10

they're

1:12

actively trying to give compression to stop bleeding.

1:14

There's also fat stranding on that

1:18

contralateral inguinal region. We know that this has been a recent

1:21

intervention. There's air foci as well.

1:24

And so really, what is the cause of this really large retroperitoneal

1:28

pelvic hematoma?

1:30

So this was the non-contrast scan, and now if we look at the arterial scan and just

1:35

focus on that hematoma and looking at its epicenter

1:39

and focusing on all the arteries that are going along it.

1:43

Out of the bat, I think we notice that the vessels are a little bit smaller in

1:47

caliber. That's what happens in the setting of vasoconstriction.

1:50

Presumably, this patient is in shock, especially in the setting of all of

1:54

this bleed, and that's why the vessels diffusely look narrow.

1:58

Other than that, we're going to focus on this right external iliac

2:02

artery, and you can see that there are some areas here

2:06

which are not seen on the non-contrast images.

2:10

And if I line up the scans perfectly at that same

2:13

level, we see some

2:17

arterial areas of blush within this hematoma

2:21

that were not there on this non-contrast scan right here.

2:25

These can sometimes be made more apparent if you do MIP imaging.

2:28

So if I

2:31

interpolated all the maximum voxels right here, I think it highlights

2:35

that this area of hyperdensity is seen a lot better now,

2:39

and it appears to arise from the right external iliac artery.

2:43

So the question is just, is this a external iliac artery vessel

2:47

branch?

2:48

Is this an active bleed? Is it a pseudoaneurysm? What is it?

2:52

And so that is why we need a delayed phase

2:56

imaging. And when we look at the delayed

3:00

phase imaging, which is the next phase, you know that this

3:04

is a delayed phase because the veins are opacified.

3:07

And if we come down to that same level, notice how the

3:10

morphology is completely different on the arterial

3:13

phase versus on the delayed phase.

3:15

This is called as contrast pooling.

3:18

In a pseudoaneurysm, the morphology would have not changed, whereas in an active

3:22

bleed between the two phases, there's pooling of contrast, and there's a lot

3:26

more contrast that's essentially leaking out.

3:29

So this is what an active bleed looks like.

3:32

If they're large enough and if they're hemodynamically unstable, typically, these

3:36

patients undergo embolization of the target vessel, which in this

3:40

case turned out to be the right external iliac artery.