The diagnosis of Crohn's disease can sometimes be challenging, aids in endoscopic diagnosis.
Endoscopy
A colonoscopy is the best test for making the diagnosis of Crohn's disease as it allows direct visualization of the colon and the terminal ileum, identifying the pattern of disease involvement. Occasionally, the colonoscope can travel past the terminal ileum but it varies from patient to patient. During the procedure, the gastroenterologist can also perform a biopsy, taking small samples of tissue for laboratory analysis which may help confirm a diagnosis. As 30% of Crohn's disease involves only the ileum,
Radiologic tests
A small bowel follow-through may suggest the diagnosis of Crohn's disease and is useful when the disease involves only the small intestine. Because colonoscopy and gastroscopy allow direct visualization of only the terminal ileum and beginning of the duodenum, they cannot be used to evaluate the remainder of the small intestine. As a result, a barium follow-through x-ray, wherein barium sulfate suspension is ingested and fluoroscopic images of the bowel are taken over time, is useful for looking for inflammation and narrowing of the small bowel. Barium enemas, in which barium is inserted into the rectum and fluoroscopy used to image the bowel, are rarely used in the work-up of Crohn's disease due to the advent of colonoscopy. They remain useful for identifying anatomical abnormalities when strictures of the colon are too small for a colonoscope to pass through, or in the detection of colonic fistulae.
CT and MRI scans are useful for evaluating the small bowel with enteroclysis protocols.They are additionally useful for looking for intra-abdominal complications of Crohn's disease such as abscesses, small bowel obstruction, or fistulae. Magnetic resonance imaging (MRI) are another option for imaging the small bowel as well as looking for complications, though it is more expensive and less readily available
Blood tests
A complete blood count may reveal anemia, which may be caused either by blood loss or vitamin B deficiency. The latter may be seen with ileitis because vitamin B is absorbed in the ileum. Erythrocyte sedimentation rate, or ESR, and C-reactive protein measurements can also be useful to gauge the degree of inflammation. It is also true in patient with ilectomy done in response to the complication. Another cause of anaemia is anaemia of chronic disease, characterized by its microcytic and hypochromic anaemia. There can be various reasons for anaemia, including medication used in treatment of inflammatory bowel disease like azathioprine which can lead to cytopenia and sulfasalazine which can also result in folate malabsorption, etc. Testing for anti-''Saccharomyces cerevisiae'' antibodies (ASCA) and anti-neutrophil cytoplasmic antibodies (ANCA) has been evaluated to identify inflammatory diseases of the intestine and to differentiate Crohn's disease from ulcerative colitis. Furthermore, increasing amounts and levels of serological antibodies such as ASCA, anti-laminaribioside ALCA, anti-chitobioside (GlcNAc(β1,4)GlcNAc(β); ACCA], anti-mannobioside anti-Laminarin [Glc(β1,3))3n(Glc(β1,6))n; anti-L and anti-Chitin anti-C associate with disease behavior and surgery, and may aid in the prognosis of Crohn's disease.
Comparison with ulcerative colitis
The most common disease that mimics the symptoms of Crohn's disease is ulcerative colitis, as both are inflammatory bowel diseases that can affect the colon with similar symptoms. It is important to differentiate these diseases, since the course of the diseases and treatments may be different. In some cases, however, it may not be possible to tell the difference, in which case the disease is classified as indeterminate colitis.
Involvement around the anus Common Seldom Bile duct involvement No increase in rate of primary sclerosing cholangitis Higher rate Distribution of Disease Patchy areas of inflammation (Skip lesions) Continuous area of inflammation In cases where remission is possible, relapse can be prevented and symptoms controlled with medication, lifestyle changes and in some cases, surgery. Adequately controlled, Crohn's disease may not significantly restrict daily living. Treatment for Crohn's disease is only when symptoms are active and involve first treating the acute problem, then maintaining remission.
Further Reading
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