0:00

Okay, so if you're watching this delayed,

0:03

stop me and preview cases 9 through 12.

0:11

Okay, let's resume.

0:12

Um, here's Mr., here's a 35 year old with abdominal pain.

0:18

I'll let this run through, looks normal.

0:26

All right, on coronal we can see there's some

0:28

free fluid, dilated loops of small bowel, and

0:32

extremely dilated loops of small bowel as well.

0:37

This grouping of small bowel shows like kind

0:38

of a nice little rosette appearance of them,

0:40

looking like a little bouquet of flowers and

0:42

demonstrates an engorged mesentery and differential

0:47

enhancement than the other small bowel loops.

0:54

So this is a closed loop obstruction, very classic.

0:56

If I could find "classicist" obstructionist,

0:59

closed loop "icist," this would be it.

1:01

It's, that's like the classic closed loop obstruction.

1:03

Um, but let's go into closed loop obstruction.

1:05

So, the radiology definition of closed loop

1:08

obstruction from the paper in 1992 that everyone always looks at is that there

1:12

is an obstruction of a bowel loop at two adjacent

1:15

points, such as an adhesion going across this

1:17

loop of small bowel or a twist of the small bowel.

1:23

So you can imagine in this case that

1:27

the bowel contents of this closed loop could

1:31

not be sucked retrograde with an NG tube

1:33

and cannot go prograde with any force.

1:37

So it's just a nice isolated loop of small bowel.

1:41

Now the surgical definition

1:43

is a little bit more expanded.

1:44

They don't use the term "at the same location."

1:47

So if you had like a long segment adhesion that

1:50

was bringing the loop of small bowel, as

1:53

long as it can't be sucked retrograde and can't

1:55

go prograde, it's considered a closed loop.

1:57

It is, it's a closed loop.

1:58

Like those are just closed.

1:59

Like you can't do anything about it.

2:00

Um, so that's a slightly, uh, broader definition of a

2:04

closed loop is the surgical definition, which

2:07

I think is more true than our, um, thought

2:09

process that we're always taught in radiology.

2:11

So, um, anything that can't be sucked

2:13

with an NG tube and can't go forward.

2:15

So our classic case, uh, closed loop here

2:19

shows dilated loops of small bowel, in

2:22

this really nice, what's referred to as,

2:25

a radial array of bowel, kind of looks like a

2:27

nice little bouquet of bowel with that engorged,

2:30

convergence of the mesenteric vasculature.

2:33

You may see cases like this where it's just very

2:35

differential enhancement of the small bowel loops.

2:37

They just have that gray because of

2:40

the engorgement of the mesentery,

2:42

very differential enhancement of the closed

2:44

loop segment from this bowel obstruction.

2:47

You may get lucky and have a double beak

2:50

sign where there is that single transition

2:52

point of both loops, as in this case.

2:55

Here's another one with a kind of a

2:56

just a closed loop with that small bowel

2:59

feces sign because of its stagnation.

3:02

Very tight there, and on the surgical

3:04

exam here you can see that just focal loop

3:06

of small bowel which had a nice adhesion

3:09

along the base causing that closed loop.

3:13

And after surgery, they kind of bring it out

3:15

here and it starts to pink up, which was good.

3:16

It was salvageable.

3:19

Here is another kind of double beak sign,

3:22

again, just that graying of the small bowel

3:24

loops over on this side, comparatively to the

3:27

small bowel loops proximal to the closed

3:29

loop, which show more normal enhancement.

3:32

You may even just see these little

3:33

U-shaped or C-shaped loops in plain.

3:36

That's a very typical one.

3:38

Here's a patient with a nice amount of mesenteric fat.

3:40

So you can see over here that there's

3:41

that engorgement of the mesentery.

3:44

Uh, vessels, whereas we have the lack

3:47

of that on the contralateral side.

3:49

All right, let's keep on moving.

3:51

Case 10.

3:55

Make sure that I'm on time here.

3:56

Okay, so here we have a dilated colon.

3:59

Am I correct?

4:00

Looks pretty dilated.

4:01

Here, um, on this side, we

4:06

have a very dilated colon all the way down.

4:09

Is this a closed loop obstruction?

4:11

Well, if you consider the distal aspect of

4:15

the obstruction, this very tight stricture,

4:17

the patient had prior colon cancer and radiation.

4:20

So that's one point of obstruction.

4:23

And if you look at the cecum, it's very large.

4:26

Here's the ileocecal valve.

4:27

You have to think of the ileocecal

4:29

valve as a Havard trap.

4:31

This is the little mouse trap that you get if

4:33

you, you know, don't want to snap the mice.

4:36

Um, and this little trap allows the mice to

4:39

go in, but the mice can't come out, right?

4:41

So if the, if there's a competent ileocecal valve, um,

4:45

any suction from above is going to be useless because

4:47

you cannot—that's going to work as the second point

4:50

of, uh, of the closed loop.

4:53

Okay, so there won't be any retrograde

4:55

flow from an NG tube or the like.

4:57

So this indeed a colonic high-grade colonic

5:00

obstruction is a closed loop obstruction.

5:03

All right, let's go into this.

5:06

Here's case 1: 77-year-old with severe

5:11

abdominal pain. On this first image you

5:13

can note here that there's some free air.

5:15

Let's start.

5:16

Now you believe me, right?

5:17

Lung windows, free air.

5:19

As you come down, you're going to see that there's

5:21

a very fluid-filled colon, very fluid-filled

5:23

colon, all the way down, fluid-filled colon,

5:27

some little tiny posts, I have air around the

5:29

right colon, around the cecum, all the way down.

5:34

You know, the tech, the surgeon's going to say to you,

5:37

where's the obstruction or where's the perforation?

5:41

Perforation, perforation, where's the perforation?

5:43

And here's all this free air.

5:45

There's little tiny dots of free

5:46

air over here on the right colon.

5:47

You're going to say, right?

5:48

Colon cecum, right?

5:51

Okay, so let's go into a quick principle.

5:55

I had to remake this slide, so we'll see how it works.

5:57

Let's talk about Laplace's law.

5:59

You may remember this from high school physics.

6:01

The Pascal principle says that in a closed system,

6:04

such as this balloon, the pressure is equal everywhere.

6:07

But the wall tension differs

6:09

based on the radius of the wall.

6:11

So the larger the radius of the wall,

6:13

the larger the wall tension, right?

6:16

So if this is one of those little balloons that

6:18

you blew up with like a little end, kind of

6:19

like you're going to make like a little poodle,

6:21

um, this system would have a

6:25

lot of wall tension at the largest radius of

6:29

the... Why does that matter in a closed system?

6:35

Um, the pressure, uh, the wall tension

6:40

is equal to the pressure and radius.

6:41

Okay, so in our small bowel, we usually

6:44

go with the three, six, nine rule, right?

6:47

The upper limits of normal of

6:48

small bowel is three centimeters.

6:49

The upper limits of normal of colon is six centimeters,

6:53

but the cecum can be up to nine centimeters.

6:56

So in our closed loop obstruction of

6:58

the colon, the cecum is our balloon, is

7:02

the very dilated part of the balloon.

7:04

Okay, so in a closed loop obstruction, the perforation

7:10

is going to occur in the cecum, most likely, but the

7:16

key is you have to let the tech, let the surgeons

7:18

know that there was a closed loop obstruction.

7:21

So in this case, deep in the pelvis, you can see

7:23

this apple core lesion of a colon cancer.

7:27

So unfortunately, this patient had a perforated colon.

7:30

They asked where the perforation was.

7:32

The radiologist who read it was

7:33

like, "Oh, a perforated cecum."

7:34

They went and took the cecum out, but no one had

7:36

highlighted the fact that the cause of the actual

7:38

perforation was the more distal obstruction

7:41

related to this, um, this colon cancer.

7:43

So you want to know that if you see a cecum, um, if you

7:47

see a, uh, colonic obstruction, a colonic perforation,

7:51

you need to find the location of the obstruction.

7:54

Usually much more distal.

7:57

Okay, so back to our case, our original case.

8:00

So this patient with a very dilated loop, dilated

8:03

colon, dilated fecal, feces-filled colon has a

8:06

closed-loop obstruction, and it's an emergency, right?

8:09

Well, MS General actually developed this technique

8:11

and I think it's being deployed everywhere now.

8:13

So it's pretty interesting in that they

8:16

will go endoscopically through the rectum.

8:19

Just and do the very best they can to slide

8:22

a stent catheter through that very narrow

8:27

colon cancer or stricture in this case.

8:29

They'll use a wire and they'll dilate

8:32

very, very slowly until they can do that.

8:34

And that's because this stent

8:37

allows for a one-stage procedure.

8:39

They can then drain the colon, drain it crazily

8:42

through this very narrow stent, and it

8:44

allows them to clean out the colon prior.

8:47

This is in a non-perforated case.

8:49

Okay, this was the case that was not perforated.

8:51

Um, it allows them to clean out the colon before

8:54

the colon perforates from pressure, um, and

8:57

allows them to, instead of doing an ostomy,

9:00

they can usually do a one-stage procedure,

9:02

um, with an anastomosis of the sigmoid colon.

9:05

So it's, it's really, um, appreciated by the

9:09

patient population, uh, that they don't have to

9:12

undergo an, um, interval, interval, uh, ostomy.

9:18

Okay.

9:19

Next case, case 12, um, is a 67

9:22

year-old with sudden abdominal pain.

9:26

As we come down here,

9:31

we're going to see a very thickened-walled

9:34

small bowel with, um, a lot of engorgement

9:38

of the mesenteric vasculature.

9:42

Maybe some dilated loops of

9:43

small bowel, but not that bad.

9:46

But notice that very engorged small bowel loops.

9:50

So you might think to yourself, Oh,

9:52

is this a, is this a small bowel?

9:53

Um, uh, is this a closed-loop obstruction?

9:56

That loop of bowel being closed

9:58

through, um, an internal hernia.

10:00

Um, and I've seen this, uh, again

10:02

and again, um, as a mistake.

10:04

So I bring that to your notice

10:06

how thick-walled the small bowel here is.

10:08

It's not as dilated.

10:09

It's enhancing as it is very thick.

10:12

And that's because this is not an internal

10:15

hernia or obstruction of the bowel.

10:18

This is a patient who has a portal vein thrombosis.

10:22

Right here, just one of the

10:23

radicals of the portal vein.

10:25

Um, so there is actual venous obstruction.

10:28

Um, the venous flow is not, um,

10:31

leaving that small bowel loop.

10:33

And as a result, this small bowel loop is

10:36

extremely engorged with a lot of vascular, a lot

10:40

of mesenteric fluid, a lot of wall thickening.

10:44

We like to call this venous ischemia, outlet

10:46

ischemia, as opposed to an arterial ischemia,

10:50

which is an inlet ischemia, such as from embolism.

10:53

This portal vein thrombosis can cause

10:55

significant, um, bowel wall thickening.

10:58

And again, can become ischemic to a

11:00

point where it needs to be resected.

11:02

Um, this patient was able to go on

11:03

for, uh, anticoagulation.

11:07

And I think they did a percutaneous portal

11:08

vein, um, intervention for thrombolysis.

11:13

And that was salvageable.

11:17

Okay, I think we're getting through these pretty quick.

11:20

We might be done a little too early for you.

11:23

Okay, preview cases 13 and 14.

11:31

Okay, um, which patient is most

11:33

likely to have pulmonary embolism?

11:35

I'll give you a second to look at it.

11:41

All right, we have patient A and patient B.

11:43

Let's look at patient A.

11:46

All right, here's four images of patient A,

11:50

but I'm going to bring you down those images.

11:52

Okay, so here we have a thrombus.

11:56

And what vessel is this?

12:00

That's the splenic vein going into the

12:01

portal venous, into the portal vein.

12:04

Now we're going to come down.

12:05

We're going to see that there's

12:06

thrombosis here of this vein.

12:08

It is anterior, anterior to the renal vein.

12:13

And as you come down deep into the pelvis, you're

12:17

going to see continued thrombosis of that vein, which

12:20

is going to the level of the sigmoid colon, where you

12:23

have a number of diverticula and mild diverticulitis.

12:27

Now this patient has fever and chills.

12:28

It's probably septic, to be honest.

12:30

Um, this is full thrombophlebitis.

12:35

of the inferior mesenteric vein.

12:37

I see this at least two to three times

12:39

a year in the setting of diverticulitis.

12:41

Um, I think once you start to look

12:43

for it, you will find it as well.

12:45

Um, so the, uh, the IMV, which is my personal

12:48

favorite, uh, vein lies in that location.

12:51

It drains into the portal vein and it goes right

12:54

anterior to the, um, to the, uh, renal vein.

12:59

So this is the beautiful IMV and

13:02

it is thrombosed in this case.

13:03

So now let's look at another case

13:05

that was kind of a corollary.

13:08

Here's a 37-year-old female with left flank pain.

13:10

Let's make this bigger and you're going to see that

13:12

there's a thrombus in the left renal vein itself coming

13:16

on down into the pelvis to the level of the ovary.

13:20

So this is gonadal vein thrombosis, as

13:23

opposed to our patient with the, with the IMV

13:27

thrombosis. Uh, this drains into the renal vein.

13:31

This is a systemic vein, and as a

13:34

result, we're going to pull this one down

13:36

again, you will see that nice rhombus

13:41

of that gonadal vein, pardon me, it's not fast, um,

13:45

and the gonadal vein, the left gonadal vein drains

13:47

into the renal artery, um, renal vein, pardon me,

13:51

uh, now I'm bamboozling you a little bit because

13:53

really it's much more common on the right, but I had

13:55

to get a left-sided one to show together, um,

13:59

and they're not that common, um, but because this is a

14:01

systemic vein as opposed to a portal vein, so the

14:04

portal vein wouldn't, uh, cause a pulmonary embolism,

14:07

maybe you would, uh, um, come off into microabscesses

14:10

into the liver in the setting of diverticulitis.

14:13

But the systemic extension of the gonadal vein

14:19

thrombosis can occur, can result in pulmonary embolism.

14:22

So in this case, which is a different patient, this

14:24

patient had renal colic and actually a renal stone.

14:27

I'm not sure exactly why they had, but I guess

14:29

from stasis, they had renal vein thrombosis.

14:32

And when you looked next, you can

14:34

see the pulmonary emboli as well.

14:35

So always look for pulmonary emboli whenever

14:37

you see a DVT, obviously in the abdomen,

14:40

um, or elsewhere, uh, because, um, you know,

14:44

that's probably what is going to be more of

14:47

of higher consequence at the time of diagnosis.