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What is Crohn’s Disease and Ulcerative Colitis?

Crohn’s disease is a chronic (ongoing) disorder that causes inflammation of the gastrointestinal (GI) or digestive tract. Most often the disease affects the end of the small intestine (inflammation of the ileum or ileitis) and/or beginning of the colon (colitis) (see Figure 1). However, Crohn’s can involve any area of the GI tract from the mouth to the anus.

Symptoms
Some of the most common symptoms of Crohn’s disease are persistent diarrhea, with or without blood, and abdominal pain,  loss of appetite and subsequent weight loss also may occur. The symptoms vary from person to person and may change over time. The disease can affect areas outside of the GI tract as well, such as the joints, skin, eyes, and liver. Another common complaint for people with IBD is fatigue, or recurrent unexplained fever. Children – may suffer delayed growth and puberty (sexual development).

Figure 1 [+] :
Various types of Crohn’s disease

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Figure 1B[+]:
Distinguishing features of Crohn’s disease

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Patients may also develop tears (fissures) in the facing of the anus, which may cause pain and bleeding, especially during bowel movements. Inflammation may also cause a narrowing (stenosis or stricture) as well as a fistula to develop (see Figure 1B). A fistula is a tunnel that leads from one loop of intestine to another, or that connects the intestine to the skin, bladder, or vagina. Fistulas occur most commonly around the anal area and can cause the drainage of mucus, stool or pus from this opening.

Since Crohn’s is a chronic disease, patients will go through periods in which the disease flares up and is active, and causes symptoms. These periods are followed by times of remission — periods in which symptoms disappear or decrease and good health returns. People with Crohn’s are usually healthy enough to lead active, normal lives.

What are the Different Types of Crohn’s Disease?

The symptoms of Crohn’s disease differ from one person to the next, even within the same family, depending on what part of the intestinal tract is inflamed (see Figure 1). The following are various types of Crohn’s disease, according to the segments of bowel affected, with their characteristic symptoms:

  • Ileocolitis: The most common form of Crohn’s, affecting the end of the small bowel (ileum) and the beginning of the large bowel (colon). Symptoms may include diarrhea and cramping or pain in the right lower part or middle of the abdomen. Often, there is significant weight loss. Complications may include fistulas or inflammatory abscess in right lower quadrant of the abdomen.
  • Ileitis: Inflammation restricted to the ileum, typically in the last segment. Symptoms are the same as ileocolitis.
  • Jejunoileitis: This distribution of Crohn’s disease is characterized by patchy areas of inflammation in the jejunum (upper half of the small intestine), as well as the ileum (lower half of the small bowel). Symptoms can include abdominal pain (ranging from mild to intense), often more intense following meals, as well as diarrhea. Fistulas may form.
  • Crohn’s (granulomatous) colitis: This form of Crohn’s disease only affects the large bowel or colon. Unlike ulcerative colitis, the colonic inflammation is usually patchy. Symptoms may include diarrhea, which may contain blood and mucus. , Involvement around the anus (abscess, fistulas, and ulcers) occurs more frequently than with other forms of Crohn’s. Also, skin lesions and joint pains are more common in this form of Crohn’s.
  • Gastroduodenal Crohn’s disease: Affects the stomach (see Figure 1C) and duodenum (the first part of the small intestine). Typical symptoms include loss of appetite, weight loss, nausea, and vomiting.

Figure 1C
Endoscopic appearance of the lining of a normal stomach (on the left), with the red inflamed lining of a patient with Crohn’s disease involving the stomach.

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