The digestive tract runs from the mouth to the anus and is made up of a hollow ‘’tube’’ that extends the entire length of the tract. The ‘’tube’’ includes the:

• esophagus
• stomach
• small intestine
• large intestine
• rectum¹

The digestive tract, along with the liver and pancreas, form the digestive system. Each aspect of the digestive system performs different functions during the nourishment process including:

• digestion of food
• absorption of nutrients
• elimination of waste.¹

 The colon is also called the large intestine and it connects to the small intestine. The colon is approximately 150 cm. long in adults and spans between the ileocecal valve and the anus.

The portions of the colon start just below the small intestine with the cecum, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and finally the rectum which is the remaining 10-12 cm. of the colon and opens to the anal canal.²

Crohn’s disease, a type of inflammatory bowel disease (IBD), causes inflammation in the gastrointestinal tract. It is a chronic and immune-mediated (autoimmune) disease.

Crohn’s disease can impact any portion of the gastrointestinal tract from the mouth to the anus, as well as systemic inflammation (extra-intestinal manifestations).

The most common location for Crohn’s disease to present is in the ileum, or the distal aspect of the small intestine, and the colon, especially the upper part of the colon, i.e., ascending colon.³

Crohn’s disease causes inflammation in a transmural fashion.  This means the inflammation occurs along the lining of the GI tract (mucosa) but also through the wall into the deeper layers.

This transmural inflammation causes pain and debilitation with risk of serious complications, such as fistula, abscess, stricture, and others that are related to bowel damage.³

The etiology of Crohn’s disease is not known, but genetics and an improperly functioning immune system are considerations in the development of the disease. Individuals with Crohn’s disease in their family history are more likely to acquire the disease themselves.

The presence of microorganisms like bacteria or viruses may activate the disease. The disease causes the immune system to attack the cells of the digestive tract.  The reason for this is not clear, but research suggests that the immune systems “attacks” microorganisms in the GI tract and in a dysregulated fashion also attacks the bowel wall.³

The symptoms of Crohn’s disease are similar to those of ulcerative colitis (diarrhea and bleeding), but often patients with Crohn’s disease have abdominal pain. It is sometimes difficult to distinguish the two based on symptoms alone.

Symptoms that are associated with inflammation of the gastrointestinal tract include:

• blood in the stools
• diarrhea
• urgency to open bowels
• abdominal pain
• cramps

Symptoms that are associated with inflammatory bowel disease include:

• weight loss
• fever
• fatigue
• loss of appetite⁴

The complications of Crohn’s disease may include abscess formation, fistula formation, and strictures that can lead to bowel obstruction. This is caused by prolonged inflammation of the intestinal wall and fibrosis (scarring) over time.

Other complications include perianal disorders like fistulas and ulcers. Further complications beyond the intestines, called extraintestinal manifestations, may include:

• arthritis
• anemia
• osteoporosis
• uveitis, and
• skin disorders³

Diagnostic tests for Crohn’s disease are used to determine the severity of the disease. These tests include:

• colonoscopy
• stool examination (fecal occult blood and exclusion of infections)
• CT/MRI scan, blood tests
• flexible sigmoidoscopy
• upper endoscopy³

The site of the disease is confirmed as being in any part of the gastrointestinal tract. The distribution of the disease is segmental and may skip around in areas of the gastrointestinal tract.

Diagnostic tests will look for complications that indicate Crohn’s disease including the common fistulae, abscesses, and strictures.

The tests will attempt to identify an increased risk of cancer, anal lesions expected about 75% of the time, and a colonoscopic appearance of focal aphthous ulcers, lineal ulcers, deep ulcers, and cobblestoning appearance in the bowel.³

Treatment options are dependent upon disease activity and severity.  Generally, mild Crohn’s disease occurs in approximately 25% of patients and may be treated with budesonide, a rapidly metabolized steroid.

5-aminosalicylates have largely been found ineffective for Crohn’s disease, but may have a place in very mild Crohn’s or mild Crohn’s of the colon only. ³

Approximately 75% of patients have moderate to severe Crohn’s disease and benefit for early treatment with biologic therapy with or without immunomodulators.  Additionally, patients with perianal disease, specifically fistula, should be treated with biologics with or without immunomodulators.

Upper gastrointestinal disease (mild/moderate): Immunomodulators with biologicals³

Ileitis (mild): Corticosteroids³

Ileitis (moderate/severe): Corticosteroids induction, Immunosuppressants and immunomodulators with biologicals, Supportive therapy for induction (nothing by mouth and total parenteral nutrition) ³

Ileocolitis/colitis (mild/moderate): Corticosteroids with proximal colon disease involvement³

Ileocolitis/colitis (moderate/severe): Corticosteroids induction, Immunosuppressants and immunomodulators with biologicals, Supportive therapy for induction (nothing by mouth and total parenteral nutrition) ³

Perianal disease (mild/moderate): Immunomodulators with biologicals³

Perianal disease (moderate/severe): Surgery, Supportive therapy for induction (nothing by mouth and total parenteral nutrition) ³

Fistulizing disease after ruling out abscess (mild/moderate): Immunomodulators with biologicals, Antibiotics at the perianal location³

Fistulizing disease after ruling out abscess (persistent): Surgery, Supportive therapy for induction (nothing by mouth and total parenteral nutrition) ³

Surgery may be required with refractory to medical therapy or perforation. ³

Patients with Crohn’s disease should maintain their regular medication schedule, but also take actions to help cope with the disease in a positive manner and help manage attacks and symptoms. This can include:

• making time for physical activity
• learning about the disease and take an active role in managing it
• Eating a healthy and well-balanced diet
• Know the triggers. Identify foods that make Chron’s disease worse and avoid them
• avoid smoking
• Plan ahead if going away from home to help manage flare-ups
• joining patient support groups for emotional support and help in managing symptoms and staying with your treatment program .⁵

1. Cheng, L.K., O’Grady, G., Du, P., et al. (2010). Gastrointestinal system. WIREs Systems Biology and Medicine, 2(1), 65-79. https://doi.org/10.1002/wsbm.19
2. Phillips, M., Patel, A., Meredith, P., et al. (2015). Segmental colonic length and mobility. Royal College of Surgeons of England, 97(6), 439-444. https://doi.org/10.1308/003588415X14181254790527
3. Baumgart, D.C. & Sandborn, W.J. (2013). Crohn’s disease, The Lancet, 380(9853), 1590-1605. https://doi.org/10.1016/S0140-6736(12)60026-9
4. Laass, M.W., Roggenbuck, D., & Conrad, K. (2014). Diagnosis and classification of Crohn’s disease. Autoimmunity Reviews, 13(4-5), 467-471. https://doi.org/10.1016/j.autrev.2014.01.029
5. Cosnes, J. (2010). Smoking, Physical Activity, Nutrition and Lifestyle: Environmental Factors and Their Impact on IBD. Digestive Diseases, 28(3), 411-417. https://doi.org/10.1159/000320395