Crohn's disease. Crohn’s disease can happen anywhere in the digestive tract. The most affected area is the end of the small intestine and the beginning of the colon, which is called the ileal colonic region. It can spread deeply into affected area, resulting in fistula, stricture, or abscess. Crohn’s disease affects the GI tract segments by segments, and usually does not distribute continuously. It rarely involves in the rectum.

Ulcerative colitis (UC). UC happens only in the large bowel (colon). In contrary to Crohn’s disease, UC generally does not cause deep inflammation, fistula, or stricture. It has a continuous appearance and involves the rectum most of the time. Picture at lower right shows the colonoscopic view of UC.

Microscopic colitis. Microscopic colitis means the lining of the large bowel looks normal, but inflammation is seen under microscopy. It has two subtypes: collagenous colitis and lymphocytic colitis depending on the containing components. Although microscopic colitis is considered as inflammatory bowel diseases, it is usually separated from classic IBD. Here, we mostly discuss about ulcerative colitis and Crohn disease.

Causes and Risk Factors

The most common ones are:

• Race. Ethnicity. Ashkenazi Jewish descent has the highest risk.
• Family history
• Live in Western world
• Cigarette smoking. Cigarette smoking is a risk factor for Crohn's disease but not UC.

Symptoms and Signs

Symptoms and signs depend on the location, type of IBD, and severity. General symptoms and signs that related to the GI tract are:

• Diarrhea
• Fever
• Chills
• Abdominal pain
• Rectal bleeding
• Fatigue
• Decreased appetite
• Weight loss

There are also symptoms and signs of IBD presented outside of the GI tract, which occur in approximately 20% of patients with IBD. The common ones are:

Skin:

• Erythema nodosum. Painful skin inflammation usually at the front of the small leg.
• Psoriasis. An itchy skin rash.
• Pyoderma gangrenosum. A skin abscess.

Joints:

• Arthritis. Inflammation in the joints, such as hands, feet, etc.

Ankylosing spondylitis. Inflammation in the spine.

Eyes:

• Uveitis. Inflammation in the eyes, causing pain and vision change, which needs emergent evaluation by an eye doctor.

Liver:

• Primary sclerosing cholangitis. This is inflammation in the bile ducts.

Common complications of IBD:

• Anemia
• Bowel stricture and obstruction. These are mostly seen in Crohn's disease.
• Anal fissure, Fistulas, and Abscess. These are mostly seen in Crohn's disease.
• Malnutrition
• Kidney stone and Gallstone
• Osteoporosis
• Colon cancer

Diagnosis and Treatment

Diagnosis of IBD is mostly based on clinical presentation with one or more of the following tests:

• Blood works
• Stool studies
• X-ray
• CT scan
• Endoscopy
• Colonoscopy

Treatment of IBD is based on the type, location, severity of symptoms, complications, etc. One or more of the following modalities are usually used for management of IBD:

• Medications
• Endoscopy
• Colonoscopy
• Surgery

References:

1. PubMed Health.
2. Wikipedia.
3. Mayo clinic online health information.
4. Sleisenger and Fordtran's Gastrointestinal and Liver Disease- by Mark Feldman MD, et al.
5. The Little Black Book of Gastroenterology-by David W. Hay.
6. Principles of Clinical Gastroenterology by Tadataka Yamada, et al.

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