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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
couldn't become impacted within the
bowel as water is absorbed from it so
you want to 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 onto
volvulus a volvulus is essentially a
closed loop obstruction involving the
large bowel it's most commonly seen in
the sigmoid area and then it's followed
by the cecal area sigmoid volvulus tends
to produce a characteristic coffee bean
shape appearance on radiographs with a
sequal volvulus you 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 the volvulus and as with a
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 does 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 as
sigmoid volvulus so a colonoscopy is
used to reduce the volvulus most often
occasionally you can use a contrast
enema however you have to be careful
because when you reduce the value list
there is a high risk of perforation so
what are other secondary science of
volvulus you can see the world scene
which is swirling of the mesentery and
that can be seen with both large
volvulus and small bowel closed-loop
obstruction you can also see what's
called the beak sign we
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 of the colon producing the
appearance of a 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 Olga V 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 that 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 the 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 does that
represent
so this is a prominent loop of airfield
small-bowel that's seen in the left
upper abdomen and this is consistent
with the focal Ilyas 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 Ilyas
so you want to obtain a CT of the
abdomen and pelvis with contrast to take
a look for any kind of causes remember
there are multiple different causes of a
small bowel focal Ilyas 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 periya pandi seal fat
stranding let's take a closer look so
this portion right here is all appendix
normally appendix should have a little
bit of 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 multiple different
causes of large and small bowel
obstruction again this is a very common
finding that you want to look out for
when you see a patient coming in with
abdominal pain
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