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- All right, solet’s talk about how to diagnose Inflammatory BowelDisease, or IBD for short. So, Inflammatory Bowel Diseaseis a group of disorders that’s caused by an inappropriateinflammatory response that results in chronic intestinal damage. And, there are two types ofinflammatory bowel disease: Crohn’s Disease and Ulcerative Colitis. And, Crohn’s disease andUlcerative Colitis can be distinguished from one anotherbased the on the location of the inflammation andthe pathalogic changes. So, the location of theinflammation here becomes really important for theclinical presentation of the disease. So, it this clinicalpresentation that will drive the diagnostic work up thatwill ultimately lead to a biopsy which will determine thepathology that makes the diagnosis of Crohn’s Disease or Ulcerative Colitis. Now, unfortunately there’sno single blood test or physical exam maneuverthat can diagnose either of the types ofInflammatory Bowel Disease. Instead, the diagnosisis made through a process that includes the clinicalpresentation, certain labratory findings, radiographicfindings, and then finally the pathologic diagnosis. So, let’s start with thehistory and physical exam. So, I just mentioned the thelocation of disease in general will dictate the clinical presentation. So, where do theselesions in Crohn’s Disease and Ulcerative Colitis occur? Well, in Crohn’s Disease thelesions are discontinuous and they can occur anywhere from the mouth to the anus. However, the most commonlocations are the terminal illium, the large intestine whichis also known as the colon, as well as then other areasin the small intestine. So, how do these locations of inflammation tend to present? Well, let’s start withthe most common location and that’s the terminal illium,which is the last section of the small intestine beforeit enters into the colon. Now, if you imagine abox over the abdomen, kind of like this, you cansee that the terminal illium is largely located inthe right lower quadrant of the individual. So, this is someone, you’relooking at the person so this is gonna be theirright side, and in the lower part of the abdomen. So, it makes sense thatinflammation of the terminal illium often results in right lowerquadrant abdominal pain. And, inflammation in this areamay also result in diarrhea that may or may not be bloody. Now, other parts of thesmall intestine may also be involved.
- And, if enough of the smallintestine is involved, which is the location whereour nutrients are absorbed from the GI tract primarily,you can get malabsorption which can result in poor nutrition. So, this can causeweight loss and fatigue. Now, the second most commonlocation of inflamation is the colon, which isjust another way of saying the large intestine. Now, the colon is mainlyresponsible for reabsorbing the water from the stool. So, if it’s inflammedand not working properly one can expect that thewater will not be reabsorbed so there’s gonna be,once again, this diarrhea which may or may not be bloody. And then, another commonpresenting symptom, although it’s not necessarilyrelated to a specific location is just this general inflammationcan result in a fever which is usually fairly mild. And then, there may be some other symptoms that are caused by someof the complications of Crohn’s Disease thatwe’ll discuss in a minute. And, these can be things likebowel obstruction that can lead to something known asobstipation, which is the inability to pass stool or gas. Or, you can have thesefistulas that can result in some fairly severe perianalpain as well as infection. Now, for Ulcerative Colitisthe lesions occur instead of in this discontinuous kinda skipmanner of Crohn’s Disease they can occur in a continuous manner. And, it typically begins inthe rectum and then kinda just moves backwardsthrough the large intestine and almost never leavesthe large intestine. So, similar to Crohn’sDisease if the large intestine is inflammed in UlcerativeColitis the most common presentation is this diarrhea with some diffuse crampy abdominal pain. And, it’s also importantto note that this diarrhea in Ulcerative Colitis isoften bloody, not always but fairly frequently bloodyand it’s more frequently bloody than in Crohn’s Diseasealthough bloody diarrhea can occur in either type ofInflammatory Bowel Disease. Now, there are a few signs andsymptoms of Crohn’s Disease and Ulcerative Colitis thatare not associated with the location of the inflammationand these are known as Extra-Intestinal Symptoms. So, one of theseextra-intestinal symptoms can be skin disease such asthese red tender nodules that are known as Erythema Nodosum. They can also includejoint pain that often seems to migrate between differentjoints such as the shoulders, elbows, hips, and knees aswell as redness of the eyes, and liver disease. Now, these extra-intestinalsymptoms in Crohn’s Disease and Ulcerative Colitis areactually pretty important because the GI symptomsof the disease can be fairly non-specific, Imean there’s a lot things that can cause right lowerquadrant abdominal pain and diarrhea. However, there are not manydiseases that will cause these abdominal symptomsor these GI symptoms in association with some ofthese extra-intestinal symptoms. So, if they’re happeningtogether that’s actually a fairly specific sign thatsomeone might have Inflammatory Bowel Disease.
- Now, since the history andphysical is fairly non-specific the next step in thisdiagnostic work up is to perform some laboratory studies. And, these studies tend tobe fairly similar between Crohn’s Disease and Ulcerative Colitis. So, let’s once again bring inthis diagram of the GI tract. So, the first set of laboratoryfindings are these markers of inflammation. And, this includes an increasedwhite blood cell count, which is known as Leukocytosis,as well a couple of other very non-specificmarkers of inflammation that include an increasedsedimentation rate and an increased C-reactive protein. Now, these findings hereare very non-specific, meaning any sort of inflammatorycondition in the body can cause these findings. However, they’re verysensitive for Inflammatory Bowel Disease, meaning thatif someone doesn’t have an increased sedimentationrate or an increased C-reactive protein the process that’sgoing on is likely not Crohn’s Disease or Ulcerative Colitis. And, another labratoryfinding 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 couplereasons why anemia can occur in Crohn’s disease and Ulcerative Colitis. In Crohn’s Disease if thisterminal illium is involved then the body is not able toproperly absorb the vitamin B-12, which in this vitaminis necessary to produce red blood cells. So, if there’s lowvitamin B-12 then it can result in anemia. Also, I mentioned thatboth Crohn’s Disease and Ulcerative Colitiscan have bloody diarrhea. If this bloody diarrheais occuring frequently and over long periodsof time that blood loss can kinda be addative andadd up and that blood loss can result in anemia. Then, the last category oflaboratory findings to mention is that f malabsorption. So, I mentioned earlier that if enough of the small intestine and evenparts of the large intestine are inflammed and not working properly then body isn’t able toabsorb all the nutrients it needs to in order to survive. This is known as malabsorption,so it’s what causes that weight loss andfatigue in Crohn’s Disease and Ulcerative Colitis. However, if the body is ina state of malabsorption and getting very poor nutritionthere’s some blood tests that can also be a marker of that. And, one of the most commonones is a low albumin level. And, albumin is just animportant protein in the body and when it’s low it’sa sign of malabsorbtion. So, similar to thehistory and physical exam the laboratory findings of Crohn’s Disease and Ulcerative Colitisare fairly non-specific. But, they’re very sensitivefor Inflammatory Bowel Disease, meaning if these findings,if none of these findings are present chances aresomeone does not have Inflammatory Bowel Diseaseand you won’t move on to the next step inthe diagnostic work up. However, if these findings,especially the markers of inflammation, are presentthen we’ll move to the next step in the diagnosticwork up which is obtaining imaging studies. Now, a number of radiographicstudies can be performed to aid in the diagnosis of Crohn’s Disease and Ulcerative Colitis,including CT and MRI. However, one of the studiesthat’s used is something known as a Barium Enema. Now, Barium is a contrastdye that is inserted through the rectum into theintestines and as it fills up the intestinal lumen anX-ray is taken to look at the abdominal cavity. And, this is a normal Barium Enema study. You can see a nicelyoutlined large intestine and when this study is performedin either Crohn’s Disease or Ulcerative Colitis thereare some characteristic findings that represent someof the underlying pathology of the two diseases. Now, there are a lot ofthings going on in this image, but what I want to pointout is that you’ll notice that the inflammation is occuring in both the large intestine as well asparts of the small intestine and it’s intermixed by fairlynormal looking sections of intestine.
- So, this is characteristicof Crohn’s Disease, which are those skiplesions that occur both in the large intestine andthe small intestine. Whereas the findings of BariumEnema for Ulcerative Colitis are fairly different. So, in Ulcerative Colitisyou’ll get this continous lesion that only involves the large intestine. So, notice that there’sno gaps of inflamation, the entire intestine isinvolved and then you get a fairly normal smallintestine afterwards. And so, it’s these radiographicfindings that lead to the next step in diagnosis,which is to obtain a biopsy to then formalize thediagnosis of Crohn’s Disease and Ulcerative Colitis. So, a number of differentprocedures can be performed to obtain a biopsy andthe decision for the type of procedure is largely basedon where the locations are for biopsy. So, say if Crohn’s diseaseis suspected and the lesion is in the first partof the small intestine then an endoscopy, or a camera is put down the throat into the esophagusand through the stomach can be performed becausethat’s the best way to get to the first part of the small intestine. Whereas in Ulcerative Colitiswhere the inflammation is contained only in thecolon then the procedure is most likely going to a sigmoidoscopy or a colonoscopy where acamera is inserted through the anus and rectum to obtain a biopsy. But, regardless of thetype of procedure the steps are the same and it’s twofold,there’s the visualization of the lesion and then thebiopsy for microscopic pathology. So, in Crohn’s diease onvisualization the lesions grossly will look something like this. And, this is known as a”cobblestone” appearance. And, it’s called this becausepathologists kind of think these lesions look somewhatlike a cobblestone path in which the intestinal wallhas numerous intersecting lesions to make this kindof cobblestone pattern. And, once this grossappearance is seen a biopsy of the intestinal wallis taken to look at under the microscope. And then, the characteristicmicroscopic findings of Crohn’s Disease are thisTransmural Inflammation in which the inflammationcaused by the disease goes through all three layersof 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 asign of chronic infection.
- Now, Ulcerative Colitishas a very different gross appearance. You can see the wallslook much more smooth because of the continuouslesion and they have what’s described as “friable” appearance. And, what friable means isthat if you were to touch the wall it kind of lookslike it would easily bleed or parts of it would just slough off. And so, when this is seen abiopsy is once again taken to look at under amicroscope where it reveals the hallmark lesion of Ulcerative Colitis which is inflammationcontained only in the mucosal and submucosal layers, which is very differentthan Crohn’s disease. So, once this pathologicspecimen has been taken and you see the hallmarkfindings of one or the other a diagnosis of Crohn’sDisease or Ulcerative Colitis can finally be made.