So let's move on to large bowel obstruction.
This is usually caused by a mechanical obstruction of the large bowel
and the cecum is usually, the part of the bowel that dilates the most.
The small bowel is often not dilated unless the obstruction is so severe
that it makes the ileocecal valve incompetent.
In a large bowel obstruction, you don’t want to administer oral barium
because it could become impacted within the bowel as water is absorbed from it.
So you wanna start off by doing a plain film and if you suspect a large bowel obstruction
then don't administer the oral contrast.
So let's move on to volvulus.
A volvulus is essentially a closed loop obstruction involving the large bowel.
It's most commonly seen in the cecal area and then it's followed by the sigmoid area.
Sigmoid volvulus tends to produce a characterized "coffee bean" shape appearance on radiographs.
With the cecal volvulus, you'll actually see a very dilated cecum that often rotates to the left upper abdomen.
On this film, you can see what appears to be a very dilated cecum.
It remains within the pelvis in this patient.
The small bowel will become dilated with volvulus
and as with the small bowel volvulus there's a very high risk of strangulation.
So let's take a look at this film, you can see the green line,
showing you a very dilated loop of large bowel, so what is this represent?
This is actually an example of a Sigmoid Volvulus
and you can see, this is the characteristic coffee bean shape that you would expect.
This is a surgical specimen demonstrating the same thing, a sigmoid volvulus.
So a colonoscopy is used to reduce the volvulus most often.
Occasionally, you can use a contract enema,
however you have to be careful because when you reduce the volvulus there is a high risk of perforation.
So what are other secondary science of volvulus.
You can see the whirl sign which is swirling of the mesentery
and that could be seen with both large volvulus and small bowel closed loop obstruction.
You can also see what's called the beak sign which is tapering the colon to the point of obstruction.
So let's take a look at these images, this is an axial CT image in a patient
that has a closed loop obstruction and here you can see what's called the beak sign.
So you can see tapering in to the colon, producing the appearance of the beak.
And then on the coronal image, keep your eye on this area right here as I scroll through.
You can see what looks like a swirling of this mesentery and this is another secondary sign of volvulus.
So Ogilvie Syndrome is actually massive dilatation of the colon without mechanical obstruction.
So as you recall, normal large bowel obstruction is often due to a mechanical obstruction.
This is one of the causes of a non-mechanical obstruction than can cause dilatation of the colon.
Usually this is due to anticholinergics which result in loss of peristalsis, trauma especially retroperitoneal.
Serious infection and cardiac disease.
So let’s go back to this case that we saw at the very beginning.
This is our 25 year old female that presents with right lower abdominal pain.
What do you see on this film?
So we see multiple loops of large bowel that contain air and that’s normal.
But how about right here? What is that represent?
So this is a prominent loop of air-filled small bowel
that seen in the left upper abdomen and this is consistent with the focal ileus.
As you can see here, it has that stacked coin appearance that we talked about.
So what's the next step? How do you figure out what's going on? Why does this patient have a focal ileus?
So you want to obtain of CT of the abdomen and pelvis with contrast to take a look for any kind of causes.
Remember there are multiple different causes of the small bowel focal ileus.
So let's take a look at this axial contrast enhanced CT scan.
And if you look right here, you actually have a very thick walled appendix with periappendiceal fat stranding.
Let's take a closer look. So this portion right here is all appendix.
Normally appendix should have a little bit air or a little bit of contrast within it
but you actually don't see the lumen at all because the wall is so thick
and if you look around it, let's take a look at normal mesentery so this area right here is normal mesentery.
Surrounding the appendix, the mesentery has a more grayish appearance and this is because of surrounding inflammation.
So this patient has an acute appendicitis that caused her focal ileus.
So we've gone over a multiple different causes, of large and small bowel obstruction.
Again this is a very common finding that you wanna look out for when you see a patient coming in with abdominal pain.