Crohn’s Disease


What is Crohn’s Disease?

Alternative names of this disease include Crohn syndrome, regional enteritis, ileitis, and granulomatous ileocolitis [1].

It is a type of Inflammatory Bowel Disease (IBD) causing prolonged inflammation in the linings of the intestinal tract [2]. It most commonly affects the ileum, but can occur anywhere from the mouth to the end of the rectum [3].


This picture shows the organs affected by Crohn’s Disease.

Crohn’s: Tracing Its Beginning

The condition was first described by Italian physician Giovanni Morgagni in 1769 [4]. From then on, successive cases were reported by John Berg and Antoni Lesniowski [5]. Amongst these, an article on terminal ileitis by gastroenterologists Crohn, Ginzburg and Oppenheimer was published on 1932. With Crohn spearheading the group, the article had made the illness popular and recognized medically. Hence, the name Crohn’s Disease [6].

Analyzing Crohn’s Through Numbers

  • In the United States of America, IBD affects approximately 500,000 to 2,000,000 individuals [3]. This rate shows a steadily increasing trend of both types: Crohn’s disease and ulcerative colitis.
  • In 2007, the prevalence of Crohn’s disease in children younger than 20 years is 43 per 100,000 population. In adults, on the other hand, it is present among 201 individuals for every 100,000 people [7].

This image depicts the global incidence of Crohn’s worldwide. Those areas in red and yellow hues have a high incidence of the illness, comprising rates of 7 and 4 to 7 per 100,000 population, respectively. On the other hand, with lower rates, the ones in green and blue shades have incidences of 1 to 4 and less than 1 per 100,000 population, respectively.

crohns incidence

Picture : Incidence of  Crohn’s Disease


  • It has a bimodal distribution of incidence. It affects people in their 20s and their 50s, and is rarely diagnosed early in childhood [8].
  • Having relatives with the disease increases one’s chance of inheriting the illness. Parents, siblings or children of those with Crohn’s disease are 3 to 20 times more likely to develop the disease [9]. Twins, meanwhile, have a greater than 55% chance of having Crohn’s  disease [10].

Crohn’s : Its Causes, Process and Risk Factors

  • The exact cause of Crohn’s is unknown. However, recently, it was believed to be an example of an autoimmune disorder, occurring when the body’s immune system mistakenly attacks and destroys healthy body tissues [11].
  • In patients with Crohn’s, the immune system takes action for a long period even without the presence of an antigen [3]. White cells then accumulate in the lining of the intestines, causing chronic inflammation, thus leading to ulcers, sores and injury to the intestines [12].
  • The disease has a genetic component, with its first mutation found to be associated with a frameshift type in the NOD2 gene [13]. It was also said to be influenced by the gene ATG16L1, inducing autophagy and inhibiting the body’s ability to attack invasive bacteria [14].
  • Crohn’s was said to be linked to increased intake of animal protein, milk protein and increased ratio of omega-6 to omega-3 polyunsaturated fatty acids. Consequently, consumption of vegetable proteins was found to decrease the risk of having Crohn’s. [15]
  • Smoking is also said to increase one’s chance of having the illness and the chance of recurrence or flares [16].
  • The drug isotretinoin was also found to be associated with the incidence of Crohn’s [17, 18].
  • According to recent studies, Crohn’s disease seems originate to from both immunologic and environmental factors. These factors triggers a genetic loci, resulting in a disturbed innate and  adaptive immune response, which eventually leads progression to the disease [8].

Crohn’s Symptoms

  • Severity of symptoms may depend on what part of the gastrointestinal tract is affected by Crohn’s.  It may even come and go with  periods of flare-ups. [7]
  • The most common of these symptoms include:
    • Abdominal pain
    • Intestinal obstructions
    • Abscesses
    • Fistulas
    • Fever
    • Diarrhea
    • Rectal bleeding
    • Weight loss [5]
  • Bleeding may be severe and persistent, and may even lead to anemia [12].
  • Less common symptoms include:
    • Eye inflammation (uveitis, photophobia, episcleritis)
    • Joint pain and swelling (arthritis, ankylosing spondylitis, sacroiliitis)
    • Skin lumps, ulcers and sores (erythema nodosum, pyoderma gangrenosum)
    • Mouth ulcers
    • Swollen gums
    • Tenesmus
    • Constipation [1,5]

crohns symptoms

This photo illustrates the different signs and symptoms present in a patient with Crohn’s disease.


Clues and Cues in Diagnosing Crohn’s

It can be difficult to diagnose; symptoms associated with the condition may also be similar to that of ulcerative colitis. Below are differences between Crohn’s Disease and Ulcerative Colitis.  [19, 20]


Crohn’s Disease Ulcerative Colitis
Location anywhere along the digestive tract Large intestine (colon)
Inflammation In patches Continuous
Pain In the lower right abdomen In the lower left abdomen
Appearance Colon wall thickened, rocky Colon wall thinner, with continuous inflammation
Bleeding Not common common
Defecation Porridge like, steatorrhea Mucoid, with blood
Tenesmus Less common More common
Fever Common Less; if present–severe
Fistula Common Seldom
Weight loss Often Seldom


Aside from a thorough history and physical examination, a series of diagnostics can help in identification of Crohn’s disease.

Its diagnosis is based on the findings noted from endoscopy, radiography, and histology. These shall include the presence of  granuloma, with transmural and asymmetrical lesions. It is from those findings, the subsequent tests and diagnostics will be based upon. [21]

Main diagnostic tools include film radiography (x-rays) and colonoscopy [22]. Colonoscopy is used to determine how much of the gastrointestinal tract is affected and is the most commonly used test to specifically diagnose the disease [12]. It also allows small tissue biopsies to be done for confirmation [3].

In around 40% of patients with Crohn’s, a cobblestone appearance is seen. This represents the ulcerated areas separated by normal tissues. [23]

crohns pathophysiology

This illustrates the pathology of the disease: cobblestone appearance, narrowed lumen, thickened wall and abscess on the intestine.


 crohns cobblestone


This is an image of an actual colonoscopy done, with pathognomonic findings of cobblestone appearance of the ileum in a patient with Crohn’s.


Barium x-ray studies can reveal distribution, nature and severity of the disease. It can show ulcerations, narrowing and fistulae in the bowel. However, it is less definitive than colonoscopy. [3]

CT and MRI scans are used to evaluate complications of this disease. Examples of intra-abdominal complications of Crohn’s disease are bowel obstructions, abscesses, and fistulae [24].

Simple laboratory examinations, like blood and stool tests, can help detect the illness.

Blood tests can diagnose anemia secondary to bleeding, and show elevated sedimentation rate, revealing signs of inflammation or infection [3,12].

Stool tests, like fecalysis and stool culture, are usually done to rule out other gastrointestinal diseases such as infection [12].

Other tests worth mentioning are albumin, C reactive protein, fecal fat, and liver function tests. They may all reveal abnormal findings, contributing to the diagnosis. [1]

Diagnostic work-up findings can also differentiate Crohn’s Disease from Ulcerative Colitis [20, 21,25]


Sign Crohn’s Disease Ulcerative Colitis
Terminal Ileum involvement Present Absent
Colon involvement Usually Always
Rectum involvement Absent Present
Anal involvement Present Absent
Bile duct involvement Absent Present
Distribution Patchy/skip lesions Continuous
Endoscopy Deep serpiginous ulcers Continuous
Depth of inflammation Transmural, deep into tissues Shallow, mucosal
Stenosis common Seldom
Granulomas Present absent

Classifications of Crohn’s

Crohn’s may be categorized according to how the disease behaves as it progresses. This was established as the 3 categories of disease presentation, as presented by the Vienna classification.


  • It is deemed as the most common complication of Crohn’s.
  • It causes an obstruction or blockage due to thickening of the intestine.
  • This then leads to narrowing of the bowel, subsequently changing the caliber of stools.

crohns stricture

The image differentiates gross differences between a normal intestine (left) and a strictured one (right).



  • Examples of which are fistulae, sores or ulcers tunneling through the affected are into the surrounding tissues.
  • This type creates small tears in the lining of the mucus membrane of the anus.
  • Abnormal passages between the bowel and other structures, hence, are created.

crohns fistula

The illustration shows presence of fistula, penetrating the affected tissues of the intestine of a patient with Crohn’s.



  • These are nonstricturing and nonpenetrating types
  • It causes inflammation without developing either strictures or fistulae.[26, 27]

Crohn’s Other Possible Complications

  • Nutritional defects such as vitamin, protein and caloric deficiencies may ensue.
  • This could also lead to the development of arthritis, skin problems, eye and mouth inflammation, gallstone formation and other liver and biliary diseases.[27]
  • A small percentage of Crohn’s patients may also develop Toxic megacolon and colorectal cancer, emphasizing the need for regular colonoscopies [28].

Cure for Crohn’s

The main goal in treating Crohn’s disease is to alleviate its symptoms.


  • These are drugs that inhibit inflammation and are metabolized by the commensal bacteria in the body.
  • Olsalazine, mesalamine, and sulfasalazine are examples of this type.
  • These can be administered per orem or thru the rectum.

Corticosteroid/ Steroids

  • These are powerful anti-inflammatory drugs for treating Crohn’s
  • Examples of which are prednisone, methyprednisolone budesonide, and hydrocortisone.
  • They are usually recommended for short-term use, particularly for remission of active disease.

Immunosuppressive drugs

  • These are used for long term therapy and for those cases which does not respond to standard therapy.
  • They maintain remission and treat fistulas and ulcers.
  • Azathioprine ,6- mercaptopurine, tracrolimus, cyclosporine, and methotrexate are examples of such.


  • These are used as treatment for fistulas, abscesses, and bacterial overgrowth.
  • They treat bacterial infection located at the wounds in the bowels.
  • Examples of which are metronidazole and ciprofloxacin.

Antitumor Necrosis Factor (TNF) Blockers

  • They are also called biologic response modifiers.
  • Genetically engineered, these are given to patients with Crohn’s of increased severity.
  • They are given as alternatives, when other treatments have failed.
  • Adalimumab, certolizumab, and infliximab are examples.[22, 29]

Surgery may be required for severe cases. Around 60-75% of people with Crohn’s need procedures to relieve their symptoms, repair damage to their digestive system, and treat related complications [30].

These procedures include bowel resection, strictureplasty, or a temporary or permanent colostomy or ileostomy [20]. They are mainly used to drain pus from abdominal and perirectal abscesses, remove a disease segment of small intestine causing obstruction, treat severe anal fistulae not responding to drugs, and eradicate internal fistulae causing infections [3].

A new treatment option is fecal bacteriotherapy, which had been successful in treating Inflammatory Bowel Disease [31].

Diet: It’s Role In Crohn’s

An adequate nutrition may minimize symptoms and prevent disease remission. Thus, patients should eat a well-balance diet, and include enough calories, protein and nutrients. The following tips may be helpful for a patient with Crohn’s disease:

  • Eating small meals throughout the day should be done.
  • One should drink small amounts of water throughout the day,
  • Foods can possibly aggravate symptoms and induce flare-ups. Below is a list of foods to avoid.
    • Alcohol
    • Butter, mayonnaise, and other dairy products
    • Carbonated beverages and caffeinated drinks
    • High fiber and gas producing foods
    • Nuts and seeds
    • Raw fruits and vegetables
    • Red meat and pork
    • Spicy foods[32, 33]

Food To Avoid

This picture represents the different kinds of food that Crohn’s patients may need to avoid, which in turn, may differ from one patient to another.



  • A low fiber with a low residue diet can lessen abdominal pain, cramping, and diarrhea related to Crohn’s disease. Foods to avoid while having a low residue diet include corn hulls, nuts, raw fruits, seeds, and vegetables.


  4. Kirsner, J. et al. Historical Aspects of Inflammatory Bowel Disease. Journal of Clinical Gastroenterology. 1988. 10 (3): 286-97.
  6. Crohn, et al. Regional Ileitis: A Pathologic and Clinical Entity. The Mount Sinai Journal of Medicine. 1932; 67 (3): 263-8.
  8. Baumgart, D. et al. Crohn’s Disease. The Lancet. 2012 November, 380 (9583); 1590-1605.
  9. Satsangi, J. The Genetics of Inflammatory Bowel Disease. Gut. 1997; 40 (5): 572-4.
  10. Tysk,c. et al. Ulcerative Colitis and Crohn’s Disease in an Unselected Population of Monoztgotic and Dizygotic Twins. A Study of Heritability and the Influence of Smoking. Gut. 1988; 29 (7): 990-6.
  11. Comalada, M. Impaires Innate Immunity in Crohn’s Disease. Trends in Molecular Medicine. 2006 Sept; 12 (9): 397-9.
  13. Ogura, y. et al. A Frameshift Mutation in NOD2 Associated With Susceptibility to Crohn’s Disease. Nature. 2001. 411 (6837): 603-6.
  14. Prescott, NJ. et al. A Nonsynonymous SNP in ATG16L1 Predisposes to Ileal Crohn’s Disease and is Independent of CARD15 and IBD5. Gastroenterology. 2007; 132 (5): 1665-71.
  15. Shoda, R. Epidemiologic Analysis of Crohn Disease in Japan: Increased Dietary Intake of n-6 Polyunsaturated Fatty Acids And Animal Protein Relates to the Increase Incidence of Crohn Disease in Japan. The American Journal of Clinical Nutrition. 1996. 63 (5): 741-5.
  16. Cosnes, j. Tobacco and IBD: Relevance in the Understanding of Disease Mechanisms and Clinical Practice. Best Practice and Research Clinical Gastroenterology. 2004; 18(3): 481-96.
  17. Reniers, DE. Et al.  Isotretinoin-induced Inflammatory Bowel Disease in an Adolescent. Annals of Pharmacotherapy. 2001 Oct.; 35 (10): 1214-6.
  18. Reddy, D. Possible Association Between Isotretinoin and Inflammatory Bowel Disease. The American Journal of Gastroenterology. 2006 July; 101 (7): 1569-73.
  21. Hanauer, S. Management of Crohn’s Disease in Adults. American Journal of Gastroenterology. 2001; 96 (3):635-43.
  23. Hara,A. et al. Crohn Disease of the Small Bowel: Preliminary Comparison Among CT Enterography, Capsule Endoscopy, Small-Bowel Follow-through , and Ileoscopy. Radiology. 1005; 2238 (1): 218-34.
  24. Zissin, R. et al. Computed Tomographic Findings of Abdominal Complications of Crohn’s Disease. Canadian Association of Radiologists Journal. 2005. 56 (1): 25-35.
  25. Kornbluth, A. Ulcerative Colitis Practice Guidelines in Adults: American College of Gastroenterology, Practice Parameters Committee. American Journal  of Gastroenterology. 2004 July; 99 (7): 1371-85.
  26. Gasche, C, et al. A Simple Classification of Crohn’s Disease: Report of the Working Party for the World Congress of Gastroenterology, Vienna. Inflammatory Bowel Diseases. 2007; 6 (1): 8-15.
  31. Borody, T, et al. Reversal of Inflammatory Bowel Disease with Recurrent Fecal Microbiota Transplants. American Journal of Gastroenterology. 2011; 106:352.
  33. Escott-Stump, S. Nutrition and Diagnosis-Related Care. 2008. 7th ed. Baltimore, MD: Lipincott Williams and Wilkins, pp. 1020.


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