MedGen

Crohn's disease is a complex, long-lasting (chronic) disorder that primarily affects the digestive system. This condition involves an abnormal immune response that causes excess inflammation. It most often affects the intestinal walls, particularly in the lower part of the small intestine (the ileum) and portions of the large intestine (the colon). However, inflammation can occur in any part of the digestive system, from the mouth to the anus. The inflamed tissues become thick and swollen, and the inner surfaces of the digestive system may develop open sores (ulcers).

Crohn's disease most commonly appears in a person's late teens or twenties, although the disease can begin at any age. Signs and symptoms tend to flare up multiple times throughout life. The most common features of this condition are persistent diarrhea, abdominal pain and cramping, loss of appetite, weight loss, and fever. Some people with Crohn's disease have blood in the stool from inflamed tissues in the intestine; over time, chronic bleeding can lead to a low number of red blood cells (anemia). In some cases, Crohn's disease can also cause inflammation affecting the joints, eyes, or skin.

Intestinal blockage is a common complication of Crohn's disease. Blockages are caused by swelling or a buildup of scar tissue in the intestinal walls. Some affected individuals also develop fistulae, which are abnormal connections between the intestine and other tissues. Fistulae occur when ulcers break through the intestinal wall and passages form between loops of the intestine or between the intestine and nearby structures (such as the bladder, vagina, or skin).

Crohn's disease is one common form of inflammatory bowel disease (IBD). Another type of IBD, ulcerative colitis, also causes chronic inflammation of the intestinal lining. Unlike Crohn's disease, which can affect any part of the digestive system, ulcerative colitis typically causes inflammation only in the colon. [from MedlinePlus Genetics]

Inflammation, or an inflammatory state in the large intestine. [from HPO]

Inflammatory bowel disease is a systemic disorder comprised of two major disorders: ulcerative colitis and Crohn disease. Crohn disease can affect any part of the digestive system while ulcerative colitis is confined to the colon. Both disorders may affect sites outside of the digestive system [from SNOMEDCT_US]

Ulcerative colitis is a chronic disorder that affects the digestive system. This condition is characterized by abnormal inflammation of the inner surface (epithelium) of the rectum and colon. The rectum and colon make up most of the length of the large intestine. The inflammation usually causes open sores (ulcers) to develop in the large intestine. Ulcerative colitis usually appears between the age of 15 and 30, although it can develop at any age. The inflammation tends to flare up multiple times throughout a person's life, which causes recurring signs and symptoms.

The most common symptoms of ulcerative colitis are cramping abdominal pain and frequent diarrhea, often with blood, pus, or mucus in the stool. Other signs and symptoms include nausea, loss of appetite, bowel urgency, fatigue, and fevers. Chronic bleeding from the inflamed and ulcerated intestinal tissue can cause a shortage of red blood cells (anemia) in some affected individuals. People with this disorder have difficulty absorbing enough fluids and nutrients from their diet and often experience weight loss. Affected children usually grow more slowly than normal. Less commonly, ulcerative colitis causes problems with the skin, joints, eyes, kidneys, or liver, which are most likely due to abnormal inflammation.

Toxic megacolon is a rare complication of ulcerative colitis that can be life-threatening. Toxic megacolon involves a widening (dilation) of the colon and an overwhelming inflammatory response. Ulcerative colitis also increases the risk of developing colon cancer, especially in people whose entire colon is inflamed and in those who have had ulcerative colitis for 8 years or more.

Ulcerative colitis is one common form of inflammatory bowel disease (IBD). Another type of IBD, Crohn's disease, also causes chronic inflammation of the intestines. Unlike ulcerative colitis, which affects only the inner surface of the large intestine, Crohn's disease can cause inflammation in any part of the digestive system, and the inflammation extends deeper into the intestinal tissue. [from MedlinePlus Genetics]

A circumscribed inflammatory and often suppurating lesion on the skin or an internal mucous surface resulting in necrosis of tissue. [from NCI]

Gastrointestinal symptoms characterized by chronic abdominal pain and altered bowel habits in the absence of any organic cause. [from NCI]

A chronic granulomatous inflammatory disease of the intestines that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms. It primarily causes abdominal pain, diarrhea which may be bloody, vomiting, or weight loss, but may also cause complications outside of the gastrointestinal tract such as skin rashes, arthritis, inflammation of the eye, tiredness, and lack of concentration. Crohn's disease is thought to be an autoimmune disease, in which the body's immune system attacks the gastrointestinal tract, causing inflammation. [from HPO]

A chronic inflammatory bowel disease that includes characteristic ulcers, or open sores, in the colon. The main symptom of active disease is usually constant diarrhea mixed with blood, of gradual onset and intermittent periods of exacerbated symptoms contrasting with periods that are relatively symptom-free. In contrast to Crohn's disease this special form of colitis begins in the distal parts of the rectum, spreads continually upwards and affects only mucose and submucose tissue of the colon. [from HPO]

Crohn''s disease affecting the small intestine. [from NCI]