History and initial tests
Before diagnostic tests for Crohn’s disease are done, the important part for the physician is to take a thorough history as there will be many clues, which will point to the diagnosis.
The examination will likely show tenderness and fullness in the right lower abdomen and some supportive signs such as for instance red, tender nodules over the pretibial areas in the lower legs (erythema nodosum).
X-ray studies such as a Barium enema (double contrast) will show that there is reflux into the terminal ileum and will show the changed contours of Crohn’s disease including narrowed bowel opening, irregularity of ileum, bowel wall thickening and nodularity. Another diagnostic test is to take X-rays after taking Barium by mouth and doing a small bowel follow through.
In this approach it is important that the radiologist and patient wait long enough for the barium to arrive at the last part of the small bowel (the ileum) to document the disease segment with the Crohn’s characteristics. There is a wide variety from patient to patient regarding the bowel transit time and the diagnostic success rate may be lower that way. All of these findings and symptoms point to the presence of an inflammatory bowel disease, but other more specific tests must follow to confirm it.
The most reliable way likely is a colonoscopy for the Crohn’s patient whose disease is in the region where the small bowel meets the colon. For the patient with gastro-duodenal symptoms a gastroduodenoscopy would be done instead. Crohn’s disease is spotty in the way it affects the bowel and some patients present with Crohn’s only in the stomach or in the duodenum. During the endoscopic procedure the gastroenterologist will take bowel biopsies, which will positively verify the diagnosis. The identifying features when examined under the microscope are focal granulomas with peri-cryptal granulomatous inflammation. In the past before a histological test it was often impossible to make a definite diagnosis of Crohn’s disease.
The physician will have to be very careful to exclude other “differential diagnoses”. Those are conditions, which could present with similar symptoms, but have different causes that would be treated differently. Sometimes there might be two or three diagnoses simultaneously and each condition would have to be treated separately to help cure the patient.
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