Inflammatory bowel disease: Diagnosis | Gastrointestinal system diseases | NCLEX-RN | Khan Academy
25
August

By Adem Lewis / in , , , , , , , /


– [Voiceover] All right, so
let’s talk about how to diagnose Inflammatory Bowel
Disease, or IBD for short. So, Inflammatory Bowel Disease
is a group of disorders that’s caused by an inappropriate
inflammatory response that results in chronic intestinal damage. And, there are two types of
inflammatory bowel disease: Crohn’s Disease and Ulcerative Colitis. And, Crohn’s disease and
Ulcerative Colitis can be distinguished from one another
based the on the location of the inflammation and
the pathalogic changes. So, the location of the
inflammation here becomes really important for the
clinical presentation of the disease. So, it this clinical
presentation that will drive the diagnostic work up that
will ultimately lead to a biopsy which will determine the
pathology that makes the diagnosis of Crohn’s Disease or Ulcerative Colitis. Now, unfortunately there’s
no single blood test or physical exam maneuver
that can diagnose either of the types of
Inflammatory Bowel Disease. Instead, the diagnosis
is made through a process that includes the clinical
presentation, certain labratory findings, radiographic
findings, and then finally the pathologic diagnosis. So, let’s start with the
history and physical exam. So, I just mentioned the the
location of disease in general will dictate the clinical presentation. So, where do these
lesions in Crohn’s Disease and Ulcerative Colitis occur? Well, in Crohn’s Disease the
lesions are discontinuous and they can occur anywhere from the mouth to the anus. However, the most common
locations are the terminal illium, the large intestine which
is also known as the colon, as well as then other areas
in the small intestine. So, how do these locations of inflammation tend to present? Well, let’s start with
the most common location and that’s the terminal illium,
which is the last section of the small intestine before
it enters into the colon. Now, if you imagine a
box over the abdomen, kind of like this, you can
see that the terminal illium is largely located in
the right lower quadrant of the individual. So, this is someone, you’re
looking at the person so this is gonna be their
right side, and in the lower part of the abdomen. So, it makes sense that
inflammation of the terminal illium often results in right lower
quadrant abdominal pain. And, inflammation in this area
may also result in diarrhea that may or may not be bloody. Now, other parts of the
small intestine may also be involved. And, if enough of the small
intestine is involved, which is the location where
our nutrients are absorbed from the GI tract primarily,
you can get malabsorption which can result in poor nutrition. So, this can cause
weight loss and fatigue. Now, the second most common
location of inflamation is the colon, which is
just another way of saying the large intestine. Now, the colon is mainly
responsible for reabsorbing the water from the stool. So, if it’s inflammed
and not working properly one can expect that the
water will not be reabsorbed so there’s gonna be,
once again, this diarrhea which may or may not be bloody. And then, another common
presenting symptom, although it’s not necessarily
related to a specific location is just this general inflammation
can result in a fever which is usually fairly mild. And then, there may be some other symptoms that are caused by some
of the complications of Crohn’s Disease that
we’ll discuss in a minute. And, these can be things like
bowel obstruction that can lead to something known as
obstipation, which is the inability to pass stool or gas. Or, you can have these
fistulas that can result in some fairly severe perianal
pain as well as infection. Now, for Ulcerative Colitis
the lesions occur instead of in this discontinuous kinda skip
manner of Crohn’s Disease they can occur in a continuous manner. And, it typically begins in
the rectum and then kinda just moves backwards
through the large intestine and almost never leaves
the large intestine. So, similar to Crohn’s
Disease if the large intestine is inflammed in Ulcerative
Colitis the most common presentation is this diarrhea with some diffuse crampy abdominal pain. And, it’s also important
to note that this diarrhea in Ulcerative Colitis is
often bloody, not always but fairly frequently bloody
and it’s more frequently bloody than in Crohn’s Disease
although bloody diarrhea can occur in either type of
Inflammatory Bowel Disease. Now, there are a few signs and
symptoms of Crohn’s Disease and Ulcerative Colitis that
are not associated with the location of the inflammation
and these are known as Extra-Intestinal Symptoms. So, one of these
extra-intestinal symptoms can be skin disease such as
these red tender nodules that are known as Erythema Nodosum. They can also include
joint pain that often seems to migrate between different
joints such as the shoulders, elbows, hips, and knees as
well as redness of the eyes, and liver disease. Now, these extra-intestinal
symptoms in Crohn’s Disease and Ulcerative Colitis are
actually pretty important because the GI symptoms
of the disease can be fairly non-specific, I
mean there’s a lot things that can cause right lower
quadrant abdominal pain and diarrhea. However, there are not many
diseases that will cause these abdominal symptoms
or these GI symptoms in association with some of
these extra-intestinal symptoms. So, if they’re happening
together that’s actually a fairly specific sign that
someone might have Inflammatory Bowel Disease. Now, since the history and
physical is fairly non-specific the next step in this
diagnostic work up is to perform some laboratory studies. And, these studies tend to
be fairly similar between Crohn’s Disease and Ulcerative Colitis. So, let’s once again bring in
this diagram of the GI tract. So, the first set of laboratory
findings are these markers of inflammation. And, this includes an increased
white blood cell count, which is known as Leukocytosis,
as well a couple of other very non-specific
markers of inflammation that include an increased
sedimentation rate and an increased C-reactive protein. Now, these findings here
are very non-specific, meaning any sort of inflammatory
condition in the body can cause these findings. However, they’re very
sensitive for Inflammatory Bowel Disease, meaning that
if someone doesn’t have an increased sedimentation
rate or an increased C-reactive protein the process that’s
going on is likely not Crohn’s Disease or Ulcerative Colitis. And, another labratory
finding in Crohn’s Disease and Ulcerative Colitis is anemia. And, anemia is a low hemoglobin count. And, hemoglobin is an important component of red blood cells. Now, there are a couple
reasons why anemia can occur in Crohn’s disease and Ulcerative Colitis. In Crohn’s Disease if this
terminal illium is involved then the body is not able to
properly absorb the vitamin B-12, which in this vitamin
is necessary to produce red blood cells. So, if there’s low
vitamin B-12 then it can result in anemia. Also, I mentioned that
both Crohn’s Disease and Ulcerative Colitis
can have bloody diarrhea. If this bloody diarrhea
is occuring frequently and over long periods
of time that blood loss can kinda be addative and
add up and that blood loss can result in anemia. Then, the last category of
laboratory findings to mention is that f malabsorption. So, I mentioned earlier that if enough of the small intestine and even
parts of the large intestine are inflammed and not working properly then body isn’t able to
absorb all the nutrients it needs to in order to survive. This is known as malabsorption,
so it’s what causes that weight loss and
fatigue in Crohn’s Disease and Ulcerative Colitis. However, if the body is in
a state of malabsorption and getting very poor nutrition
there’s some blood tests that can also be a marker of that. And, one of the most common
ones is a low albumin level. And, albumin is just an
important protein in the body and when it’s low it’s
a sign of malabsorbtion. So, similar to the
history and physical exam the laboratory findings of Crohn’s Disease and Ulcerative Colitis
are fairly non-specific. But, they’re very sensitive
for Inflammatory Bowel Disease, meaning if these findings,
if none of these findings are present chances are
someone does not have Inflammatory Bowel Disease
and you won’t move on to the next step in
the diagnostic work up. However, if these findings,
especially the markers of inflammation, are present
then we’ll move to the next step in the diagnostic
work up which is obtaining imaging studies. Now, a number of radiographic
studies can be performed to aid in the diagnosis of Crohn’s Disease and Ulcerative Colitis,
including CT and MRI. However, one of the studies
that’s used is something known as a Barium Enema. Now, Barium is a contrast
dye that is inserted through the rectum into the
intestines and as it fills up the intestinal lumen an
X-ray is taken to look at the abdominal cavity. And, this is a normal Barium Enema study. You can see a nicely
outlined large intestine and when this study is performed
in either Crohn’s Disease or Ulcerative Colitis there
are some characteristic findings that represent some
of the underlying pathology of the two diseases. Now, there are a lot of
things going on in this image, but what I want to point
out is that you’ll notice that the inflammation is occuring in both the large intestine as well as
parts of the small intestine and it’s intermixed by fairly
normal looking sections of intestine. So, this is characteristic
of Crohn’s Disease, which are those skip
lesions that occur both in the large intestine and
the small intestine. Whereas the findings of Barium
Enema for Ulcerative Colitis are fairly different. So, in Ulcerative Colitis
you’ll get this continous lesion that only involves the large intestine. So, notice that there’s
no gaps of inflamation, the entire intestine is
involved and then you get a fairly normal small
intestine afterwards. And so, it’s these radiographic
findings that lead to the next step in diagnosis,
which is to obtain a biopsy to then formalize the
diagnosis of Crohn’s Disease and Ulcerative Colitis. So, a number of different
procedures can be performed to obtain a biopsy and
the decision for the type of procedure is largely based
on where the locations are for biopsy. So, say if Crohn’s disease
is suspected and the lesion is in the first part
of the small intestine then an endoscopy, or a camera is put down the throat into the esophagus
and through the stomach can be performed because
that’s the best way to get to the first part of the small intestine. Whereas in Ulcerative Colitis
where the inflammation is contained only in the
colon then the procedure is most likely going to a sigmoidoscopy or a colonoscopy where a
camera is inserted through the anus and rectum to obtain a biopsy. But, regardless of the
type of procedure the steps are the same and it’s twofold,
there’s the visualization of the lesion and then the
biopsy for microscopic pathology. So, in Crohn’s diease on
visualization the lesions grossly will look something like this. And, this is known as a
“cobblestone” appearance. And, it’s called this because
pathologists kind of think these lesions look somewhat
like a cobblestone path in which the intestinal wall
has numerous intersecting lesions to make this kind
of cobblestone pattern. And, once this gross
appearance is seen a biopsy of the intestinal wall
is taken to look at under the microscope. And then, the characteristic
microscopic findings of Crohn’s Disease are this
Transmural Inflammation in which the inflammation
caused by the disease goes through all three layers
of the intestinal wall: the mucosa, the submucosa,
and the muscularis externa as well as these noncaseating granulomas which is demonstrated here. And, these granulomas are a
sign of chronic infection. Now, Ulcerative Colitis
has a very different gross appearance. You can see the walls
look much more smooth because of the continuous
lesion and they have what’s described as “friable” appearance. And, what friable means is
that if you were to touch the wall it kind of looks
like it would easily bleed or parts of it would just slough off. And so, when this is seen a
biopsy is once again taken to look at under a
microscope where it reveals the hallmark lesion of Ulcerative Colitis which is inflammation
contained only in the mucosal and submucosal layers, which is very different
than Crohn’s disease. So, once this pathologic
specimen has been taken and you see the hallmark
findings of one or the other a diagnosis of Crohn’s
Disease or Ulcerative Colitis can finally be made.


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