Crohn's Disease

Crohn's Disease

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Crohn's Disease is a chronic inflammatory disease that primarily affects the terminal ileum (the distal part of the small intestine) and the right colon (the large intestine). However, it can affect any portion of the alimentary canal. In the large majority of cases the disease is limited to the colon or ileum and can be diagnosed with a colonoscopy. In the remaining cases, the more proximal small intestine and rarely the upper digestive tract (duodenum, stomach, esophagus) might be involved.

The disease tends to cause small bowel stenosis (narrowing of the lumen) which in turn can cause complete intestinal obstruction. The disease evolves with an intermittent clinical course with periods of inactivity and flares. It tends to recur even after surgery has removed the affected intestine. The symptoms vary according to disease type and evolution: predominant inflammation (active disease, deep ulcers - causes mostly diarrhea); predominant stenosis (mostly pain); predominant perianal disease (with inflammation spreading deeply into the tissues - discharge and local pain in the genital area); and mixed clinical pictures.


Interior of colon

Crohn's disease is a chronic disease that can cause inflammation anywhere from the mouth to the anus along the lining of the digestive tract.

It is fundamental to make an accurate diagnosis of the disease, which should be based on clinical, endoscopic/histological, radiological and laboratory findings.

Endoscopy deals with the appearance of the intestine during a colonoscopy. It usually shows a deeply ulcerated mucosa (with loss of tissue) and inflammation. Affected areas may alternate with areas completely normal.

Histology refers to the microscopic analysis of the tissue biopsies taken during endoscopy and also shows inflammation and features of tissue destruction typical of this disease.

Radiology is especially useful to evaluate areas which cannot be reached by colonoscopy or to evaluate the degree of inflammation or scarring within the intestinal wall - and this can nicely be done by magnetic resonance imaging (MRI).

The signs and symptoms experienced by the patient with Crohn's disease might include pain, diarrhea, bleeding, and can overlap with many other diseases. Likewise, blood and stool tests (e.g. C-Reactive Protein, fecal calprotectin and lactoferrin, complete blood count) might also indicate inflammation or blood loss but they are not specific for Crohn's disease.

Not infrequently, Crohn's disease is not promptly diagnosed and symptoms are attributed to other conditions such as irritable bowel syndrome. On the other hand, sometimes Crohn's disease is incorrectly diagnosed because of the presence of pain or diarrhea - when the symptoms are actually due to an infection or another temporary problem. The consequences of a wrong diagnosis can clearly be very negative for the patient. A prompt diagnosis is especially important in children or adolescents since Crohn's disease can cause growth failure, which is irreversible.

When diagnosing Crohn's disease it is also crucial to obtain an accurate picture of the location, severity, and type of disease. These features greatly affect the subsequent medical or surgical management.


The clinical picture consists of subjective symptoms (pain) and objective signs (diarrhea, bleeding). Symptoms might vary according to disease stage, type, activity and location. Most often the pain is long standing and located in the right lower quadrant of the abdomen. Pain is often severe when the disease has caused a partial obstruction of the intestine and becomes unbearable when the occlusion is complete. In the latter case there is severe constipation as well. Outside of that situation diarrhea is a very frequent symptom. There may be low-grade fever, rectal bleeding, weight loss, deep fatigue, or loss of appetite. If the disease has caused infectious complications—(i.e. an abscess) a painful mass can be felt in the right lower quadrant. The disease can also be localized in the perianal area (near the anus and genitals) causing pain, discharge (from a fistula, an abnormal passage between a hollow or tubular organ and the body surface, or between two hollow or tubular organs) or abscess formation.


In uncomplicated forms of Crohn’s disease the treatment is medical while if there are complications such as intestinal stenosis, bleeding, perianal issues, Crohn’s disease must be managed together with a surgeon. The medications most commonly used are steroids, immunosuppressants (e.g. azathioprine/6-mercaptopurine) and biologic (anti-TNF) agents such as infliximab, adalimumab and certolizumab.

In milder forms topically acting steroids (such as budesonide) or immunosuppressants might keep the disease under control. Typical steroids such as cortisone should only be used during flares and for limited periods of time (given their long-term side effects). Until a few years ago a medical step-up approach was recommended (e.g. starting with the less effective medicine and escalating treatment if ineffective). Today, the trend is to use the most powerful medications (i.e. biologic agents) from the outset since they seem to be the only ones capable of limiting disease progression (e.g. avoiding the development of complications, and possibly avoiding surgery altogether). However these medications should be used with caution and by expert physicians since they can cause serious side effects. When anti-TNF agents fail the medical options become scarce and might involve still other biologics - such as natalizumab or newer optons (still not FDA approved) such as vedolizumab or ustekinumab – or surgery (though relapse after surgery is a common event).

When surgery is needed a number of options are available and include resection of the affected intestine, repair of strictures by special techniques (stricturoplasty), and drainage of collections/removal of fistulas and cleaning of the site for perianal disease. Especially in the latter case close collaboration between the gastroenterologist and the surgeon is mandatory.

Diet can also help in specific situations (e.g. low fiber diet might decrease diarrhea during a flare up). Also, an elemental diet (i.e. food essentially pre-digested and hence easy to be absorbed) has been proven effective in children and adults to control the disease – however this food is often deemed unpleasant by most patients.