Crohn's Disease

Crohn’s disease is a chronic inflammatory bowel disease that causes abdominal pain.

  • Crohn’s disease is a chronic inflammatory disease of the gastrointestinal (digestive, GI) tract.
  • Symptoms of Crohn’s disease include:
    • Abdominal pain
    • Diarrhea
    • Vomiting
    • Fever
    • Bloody diarrhea
    • Anal fistulae
    • Perirectal abscesses
    • Weight loss
  • The cause of Crohn’s disease is unknown.
  • Crohn’s disease is not contagious. You cannot “get” it from another person.
  • Diet can affect and trigger Crohn’s disease flare-ups; however, it is doubtful that diet causes it.
  • Researchers and doctors do not know the cause of Crohn’s disease; however, some suspect that the reason is due to certain bacteria, for example, mycobacterium.
  • Crohn’s disease can cause ulcers in the small intestine, colon, or both. The condition also may obstruct the small intestine.
  • Associated signs and symptoms of Crohn’s disease include reddish, tender skin nodules, and inflammation of the joints, spine, eyes, and liver.
  • Crohn’s disease and ulcerative colitis (another chronic inflammatory condition of the colon) are inflammatory bowel disease (IBD).
  • The diagnosis of Crohn’s disease is made by barium enema, barium X-ray of the small bowel, and colonoscopy.
  • The choice of treatment for Crohn’s disease depends on the location and severity of the disease.





  • Treatment of Crohn’s disease includes 5-ASA compounds and corticosteroids, topical antibiotics, immunomodulators, and biosimilars drugs for suppressing inflammation of the immune system, antibiotics, and surgery.
  • Crohn’s disease complications include megacolon and rupture of the intestine, painful eye conditions, arthritis, inflammation of the low back and spine, hepatitis, cirrhosis, jaundice, and cancer.
  • Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are two different problems with the digestive tract (gastrointestinal, GI).


Crohn’s Disease


Crohn’s disease (sometimes called Crohn disease) is a chronic inflammatory disease of the intestines. It primarily causes ulcerations (breaks in the mucosal lining) of the small and large intestines. Still, it can affect the digestive system anywhere from the mouth to the anus. It is named after the physician who described the disease in 1932. It also is called granulomatous enteritis or colitis, regional enteritis, ileitis, or terminal ileitis.


Crohn’s disease is related closely to another chronic inflammatory condition that involves only the colon called ulcerative colitis. Together, Crohn’s disease and ulcerative colitis are referred to as inflammatory bowel disease (IBD). Ulcerative colitis and Crohn’s disease have no medical cure. Once the conditions begin, they tend to fluctuate between periods of inactivity (remission) and activity (relapse).


Men and women are affected equally by inflammatory bowel disease. Americans of European Jewish descent are more likely to develop IBD than the general population. IBD has historically been considered a disease of Caucasians predominately, but there has been an increase in the reported cases in African Americans. The prevalence appears to be lower among Hispanic and Asian populations. IBD most commonly begins during adolescence and early adulthood (usually between 15 and 35). There is a small second peak of newly diagnosed cases after age 50. The number of new cases (incidence) and the number of cases (prevalence) of Crohn’s disease in the United States are rising. However, the reason for this is not entirely understood.


Crohn’s disease tends to be more common in relatives of patients with Crohn’s disease. If a person has a relative with the disease, his/her risk of developing the disease is estimated to be at least ten times that of the general population and 30 times more significant if the relative with Crohn’s disease is a sibling. It also is more common among relatives of patients with ulcerative colitis.


Types of Crohn’s Disease


Common symptoms of Crohn’s disease include abdominal pain, diarrhea, and weight loss. Less common symptoms include

  • poor appetite,
  • fever,
  • night sweats,
  • rectal pain, and
  • occasionally rectal bleeding.


The symptoms of Crohn’s disease are dependent on the location, the extent, and the severity of the inflammation. The different subtypes of Crohn’s disease and their symptoms are:

  • Crohn’s colitis is inflammation that is confined to the colon. Abdominal pain and bloody diarrhea are common symptoms. Anal fistulae and perirectal abscesses also can occur.
  • Crohn’s enteritis refers to inflammation confined to the small intestine (the second part, called the jejunum or the third part, called the ileum). The involvement of the ileum alone is referred to as Crohn’s ileitis. Abdominal pain and diarrhea are common symptoms. Obstruction of the small intestine also can occur.
  • Crohn’s terminal ileitis is inflammation that affects only the very end of the small intestine (terminal ileum), the part of the small intestine closest to the colon. Abdominal pain and diarrhea are common symptoms. Small intestinal obstruction also can occur.
  • Crohn’s enterocolitis and ileocolitis are terms to describe inflammation that involves both the small intestine and the colon. Bloody diarrhea and abdominal pain are common symptoms. Small intestinal obstruction also can occur.
  • Crohn’s terminal ileitis and ileocolitis are the most common types of Crohn’s disease. (Ulcerative colitis frequently involves only the rectum or rectum and sigmoid colon at the colon’s distal end. These are called ulcerative proctitis and procto-sigmoiditis, respectively.)


Up to one-third of patients with Crohn’s disease may have one or more of these conditions, symptoms, and signs that involve the anal area affected.

  1. Swelling of the anal sphincter’s tissue, the muscle at the end of the colon that controls defecation.
  1. Development of ulcers and fissures (long ulcers) within the anal sphincter. These ulcers and cracks can cause bleeding and pain with defecation.
  1. Development of anal fistulae (abnormal tunnels) between the anus or rectum and the skin surrounding the anus). Mucous and pus may drain from the openings of the fistulae on the skin.
  2. Development of perirectal abscesses (collections of pus in the anal and rectal area). Peri-rectal abscesses can cause fever, pain, and tenderness around the anus.


Causes of Crohn’s Disease

The cause of Crohn’s disease is unknown. Some scientists suspect that certain bacteria, such as strains of mycobacterium, may be the cause of Crohn’s disease. Crohn’s disease is not contagious. Diet may affect Crohn’s disease; however, it is unlikely that diet is responsible for causing it.

Activation of the immune system in the intestines appears to be important in IBD. The immune system is composed of immune cells and the proteins that these immune cells produce. These cells and proteins usually defend the body against harmful bacteria, viruses, fungi, and other foreign invaders. Activation of the immune system causes inflammation within the tissues where the activation occurs. (Inflammation is an essential mechanism of defense used by the immune system.)

Usually, the immune system is activated only when the body is exposed to harmful invaders. In individuals with IBD, the immune system is abnormally and chronically activated in the absence of any known invader. This results in chronic inflammation and ulceration. The susceptibility to abnormal activation of the immune system is genetically inherited. Thus, first degree relatives (brothers, sisters, children, and parents) of people with IBD are more likely to develop these diseases. Recently a gene called NOD2 has been identified as being associated with Crohn’s disease. This gene is essential in determining how the body responds to some bacterial products. Individuals with mutations in this gene are more susceptible to developing Crohn’s disease.

Other genes are still being discovered and studied, which are essential in understanding Crohn’s disease’s pathogenesis, including autophagy-related 16-like 1 gene (ATG 16L1) and IRGM, which both contribute to macrophage defects and have been identified with the Genome-Wide Association Study. There also have been studies that show that in the intestines of individuals with Crohn’s disease, there are higher levels of a specific type of bacterium, E. coli, which might play a role in the disease. The one postulated mechanism by which this could occur is through a genetically determined defect in eliminating the E. coli by intestinal mucosal macrophages. The exact roles that these various factors play in the development of this disease remain unclear.


Differences between Crohn’s Disease and Ulcerative Colitis

While ulcerative colitis causes inflammation only in the colon (colitis) and or the rectum (proctitis), Crohn’s disease may cause inflammation in the colon, rectum, small intestine (jejunum and ileum), and, occasionally, even the stomach, mouth, and esophagus.

The patterns of inflammation in Crohn’s disease are different from ulcerative colitis. Except in the most severe cases, the inflammation of ulcerative colitis tends to involve the superficial layers of the bowel’s inner lining. The inflammation also tends to be diffuse and uniform (all of the lining in the intestine’s affected segment is inflamed).


Unlike ulcerative colitis, the inflammation of Crohn’s disease is concentrated in some areas more than others. It involves layers of the bowel that are deeper than the superficial inner layers. The affected segment(s) of the bowel in Crohn’s disease is often studded with deeper ulcers with normal lining between them.


Crohn’s Disease and the Intestines


In the early stages, Crohn’s disease causes small, scattered, shallow, crater-like ulcerations (erosions) on the inner surface of the bowel. These erosions are called aphthous ulcers. With time, the erosions become more profound and more extensive, ultimately becoming true ulcers (which are more profound than erosions) and causing the bowel’s scarring and stiffness. As the disease progresses, the bowel becomes increasingly narrowed and ultimately can become obstructed. Deep ulcers can cause puncture holes or perforations in the bowel wall, and bacteria from within the bowel can spread to infect adjacent organs and the surrounding abdominal cavity.


When Crohn’s disease narrows the small intestine to the obstruction point, the flow of the contents through the intestine ceases. Sometimes, the obstruction can be caused suddenly by poorly digestible fruit or vegetable matter that plugs the already-narrowed segment of the intestine. When the intestine is obstructed, food, fluid, and gas from the stomach and the small intestine cannot pass into the colon. The symptoms of small intestinal obstruction then appear, including severe abdominal cramps, nausea, vomiting, and abdominal distention. Obstruction of the small intestine is much more likely since the small intestine is much narrower than the colon.


Deep ulcers can cause puncture holes or perforations in the small intestine and the colon walls and create a tunnel between the intestine and adjacent organs. If the ulcer tunnel reaches an adjoining space inside the abdominal cavity, a collection of infected pus (an abdominal abscess) is formed. Individuals with abdominal abscesses can develop tender abdominal masses, high fevers, and abdominal pain.

  • When the ulcer tunnels into an adjacent organ, a channel (fistula) are formed.
  • The formation of a fistula between the intestine and the bladder (enteric-vesicular fistula) can cause frequent urinary tract infections and gas and feces’ passage during urination.
  • When a fistula develops between the intestine and the skin (enteric-cutaneous fistula), pus and mucous emerge from a small painful opening on the abdomen’s skin.
  • The development of a fistula between the colon and the vagina (colonic-vaginal fistula) causes gas and feces to emerge through the vagina.
  • The presence of a fistula from the intestines to the anus (anal fistula) leads to a discharge of mucous and pus from the fistula’s opening around the anus.



Procedures and Diagnoses of Crohn’s Disease


There is no specific diagnostic test for Crohn’s disease. The diagnosis of Crohn’s disease is suspected in patients with fever, abdominal pain and tenderness, diarrhea with or without bleeding, and anal conditions, such as ulcers or fissures.


Laboratory blood tests may show elevated white blood cell counts and sedimentation rates, suggesting infection or inflammation. Other blood tests may show low red blood cell counts (anemia), low blood proteins, and low body minerals, reflecting the loss of these minerals due to chronic diarrhea.


Barium X-ray studies can be used to define the distribution, nature, and severity of the disease. Barium is a chalky material that is visible by X-ray and appears white on X-ray films. When barium is ingested orally (upper GI series), it fills the intestine, and pictures (X-rays) can be taken of the stomach and the small intestines. When barium is administered through the rectum (barium enema), images of the colon and the terminal ileum can be obtained. Barium X-rays can show ulcerations, narrowing, and, sometimes, fistulae of the bowel.


Direct visualization of the rectum and the large intestine can be accomplished with flexible viewing tubes (colonoscopes). Colonoscopy is more accurate than barium X-rays in detecting small ulcers or small inflammation areas of the colon and terminal ileum. Colonoscopy also allows for small tissue samples (biopsies) to be taken and sent for examination under the microscope to confirm Crohn’s disease diagnosis. Colonoscopy also is more accurate than barium X-rays in assessing the degree (activity) of inflammation.


Computerized axial tomography (CAT or CT) scanning is a computerized X-ray technique that allows imaging of the entire abdomen and pelvis. It can be especially helpful in detecting abscesses. CT and MRI enterography are imaging techniques that use oral contrast agents consisting of watery solutions with or without low concentrations of barium to provide adequate luminal distension and have been reported to be superior in evaluating small bowel pathology in patients Crohn’s disease.


Video capsule endoscopy (VCE) has also been added to the tests for diagnosing Crohn’s disease. For video capsule endoscopy, a capsule containing a miniature video camera is swallowed. As the capsule travels through the small intestine, it sends video images of the small intestine’s lining to a receiver carried on a belt at the waist. The images are downloaded and then reviewed on a computer. The value of video capsule endoscopy is that it can identify the early, mild abnormalities of Crohn’s disease. Video capsule endoscopy may be particularly useful when there is a strong suspicion of Crohn’s disease, but the barium X-rays are normal. (Barium X-rays are not as good at identifying early, mild Crohn’s disease.) In a prospective blinded evaluation, video capsule endoscopy was demonstrated to be superior in its ability to detect small bowel pathology missed on small bowel radiographic studies and CT exams.


Video capsule endoscopy should not be performed in patients who have an obstruction of the small intestine. The capsule may become stuck at the site of obstruction and make the obstruction worse. Doctors usually also are reluctant to perform video-capsule endoscopy for the same reason in patients whom they suspect of having small intestinal strictures (narrowed segments of the small intestine that can result from prior surgery, prior radiation, or chronic ulceration, for example, from Crohn’s disease). There is also a theoretical concern for electrical interference between the capsule and implanted cardiac pacemakers and defibrillators; however, so far, in a small-moderate number of patients with pacemakers or defibrillators video capsule endoscopy, there have been no problems.


Cure and Prognosis of Crohn’s Disease

  • There is no cure for Crohn’s disease, only treatments for pain and other symptoms.
  • Crohn’s disease is a chronic inflammatory disease involving predominantly the small intestine and colon. The signs and the activity of the disease can come and go. Even though many effective medications are available to control the disease’s movement, there is as yet no cure for Crohn’s disease.
  • Surgery can significantly improve the quality of life in selected individuals. Still, the recurrence of the disease after surgery is common.
  • Crohn’s disease can have complications, both within and outside of the intestine.
  • Newer treatments are actively being evaluated.
  • A better understanding of the role of genetics and environmental factors in the cause of Crohn’s disease may lead to improved treatments and prevention of the disease.