Crohn’s Disease: Diagnosis, Causes and Treatment


Overview of Crohn’s disease

Crohn’s disease is a type of inflammatory bowel disease (IBD) that may affect any part of the gastrointestinal tract from mouth to anus. Signs and symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, and weight loss. Other complications may occur outside the gastrointestinal tract and include anemia, skin rashes, arthritis, inflammation of the eye, and tiredness.

The skin rashes may be due to infections as well as pyoderma gangrenosum or erythema nodosum. Bowel obstruction may occur as a complication of chronic inflammation, and those with the disease are at greater risk of bowel cancer.
While the cause of Crohn’s disease is unknown, it is believed to be due to a combination of environmental, immune, and bacterial factors in genetically susceptible individuals. It results in a chronic inflammatory disorder, in which the body’s immune system attacks the gastrointestinal tract, possibly targeting microbial antigens.
While Crohn’s is an immune-related disease, it does not appear to be an autoimmune disease (in that the immune system is not being triggered by the body itself). The exact underlying immune problem is not clear; however, it may be an immunodeficiency state.

About half of the overall risk is related to genetics with more than 70 genes having been found to be involved. Tobacco smokers are twice as likely to develop Crohn’s disease as nonsmokers.It also often begins after gastroenteritis. Diagnosis is based on a number of findings including biopsy and appearance of the bowel wall, medical imaging and description of the disease. Other conditions that can present similarly include irritable bowel syndrome and Behçet’s disease.

Signs and symptoms Crohn’s disease

People with Crohn’s disease can have severe symptoms followed by periods of no symptoms that can last for weeks or years. The symptoms depend on where the disease happens and how severe it is. You might notice:


Crohn’s disease causes two types of complications:

  • Local, which affect just the intestines
  • Systemic, which affect your whole body. You might hear them called extraintestinal

Other symptoms Crohn’s disease

Some people with Crohn’s disease also have:
  • A high temperature (fever)
  • feeling and being sick
  • joint pains
  • sore, red eyes
  • patches of painful, red and swollen skin – usually on the legs
  • mouth ulcers
NB: Children with Crohn’s disease may grow more slowly than usual.


While the exact cause is unknown, Crohn’s disease seems to be due to a combination of :
  • immune system disorder
  • environmental factors and
  • genetic predisposition.

Crohn’s is the first genetically complex disease in which the relationship between genetic risk factors and the immune system is understood in considerable detail. Each individual risk mutation makes a small contribution to the overall risk of Crohn’s.

The genetic data, and direct assessment of immunity, indicates a malfunction in the innate immune system. In this view, the chronic inflammation of Crohn’s is caused when the adaptive immune system tries to compensate for a deficient innate immune system.

How do immune system problems relate to Crohn’s disease?

Scientists have linked immune system problems to inflammatory bowel disease (IBD), including Crohn’s. Usually, cells of the immune system defend the body from harmful microbes — bacteria, viruses, fungi, and other foreign substances — that have entered it. The body doesn’t usually respond to all microbes, however. Many microbes are helpful, especially for digestion. And so the immune system leaves them alone.


If there is an invader that needs to be eliminated, your body’s defense reaction begins. This immune system response causes inflammation. Immune system cells, chemicals, and fluids flood to the site to overcome the offending substance. After the substance has been disabled or removed, the immune response ends. Inflammation subsides.
For some reason, though, people with Crohn’s disease have an immune system that reacts inappropriately. The immune system may be defending the body against helpful microbes by mistake. Or, for some other reason, the inflammatory response simply will not stop. Either way, over time, this chronic inflammation in the digestive system can result in ulcers and other injuries to the intestines.

Is genetics connected to Crohn’s disease?

Brothers, sisters, children, and parents of persons with IBD, including Crohn’s disease, are slightly more likely to develop the disease themselves. About 10% to 20% of people with Crohn’s disease have at least one other family member who also has the disease. The condition is more common in certain ethnic groups, such as Jews, and is more prevalent in Caucasians.

Scientists have identified a gene associated with Crohn’s disease. This gene helps the body decide how to react to certain microbes. If the gene has changed or mutated in some way, your body’s reaction to microbes may also be different from the normal reaction. Over time, IBD or Crohn’s disease may develop. People with Crohn’s disease have this mutated gene twice as often as people who do not have the disease.

Environmental factors

The increased incidence of Crohn’s in the industrialized world indicates an environmental component. Crohn’s is associated with an increased intake of animal protein, milk protein and an increased ratio of omega-6 to omega-3 polyunsaturated fatty acids.
Those who consume vegetable proteins appear to have a lower incidence of Crohn’s disease. Consumption of fish protein has no association. Smoking increases the risk of the return of active disease (flares).
The introduction of hormonal contraception in the United States in the 1960s is associated with a dramatic increase in incidence, and one hypothesis is that these drugs work on the digestive system in ways similar to smoking. Isotretinoin is associated with Crohn’s.


Although stress is sometimes claimed to exacerbate Crohn’s disease, there is no concrete evidence to support such claim. Dietary microparticles, such as those found in toothpaste, have been studied as they produce effects on immunity, but they were not consumed in greater amounts in patients with Crohn’s


This condition has many symptoms that are the same as those for other health problems.
To make a diagnosis of Crohn’s disease, your doctor is likely to gather information from multiple sources. You’ll probably go through a combination of exams, lab tests, and imaging studies with these goals in mind:
  • Rule out other health problems
  • Make a clear diagnosis of Crohn’s disease
  • Find out exactly which part of the digestive tract is affected

Physical Exam and History

Your doctor will begin by gathering information about your health and your family health history. She’ll do a physical exam and look for symptoms of Crohn’s that usually include:
  • Belly pain and cramps
  • Blood in your poop
  • Diarrhea
  • Drainage from a painful sore near your anus
  • Fatigue
  • Fever
  • Lack of appetite
  • Mouth sores
  • Urgent bowel movements
  • Weight loss

Lab Tests

Your doctor may request lab tests in order to look for problems that might be linked to Crohn’s disease. These tests check for signs of infection, inflammation, internal bleeding, and low levels of substances such as iron, protein, or minerals.
Blood tests may include:
  • Antibody tests: These help doctors tell if you have Crohn’s or ulcerative colitis:
    • Anti-Saccharomyces cerevisiae antibody test (ASCA): People with this protein are more likely to have Crohn’s.
    • Perinuclear anti-neutrophil cytoplasmic antibody test (pANCA): People with this protein are more likely to have ulcerative colitis.
  • Complete blood count (CBC): It checks for anemia (low numbers of red blood cells) and infection.
  • C-reactive protein: It looks for this protein, which is a sign of inflammation.
  • Electrolyte panel: Your body might be low on minerals like potassium if you have Crohn’s-related diarrhea.
  • Erythrocyte sedimentation rate: This gauges the amount of inflammation in your system by measuring the amount of time it takes for your blood to fall to the bottom of a special tube.
  • Iron and B12 levels: These can be low if your small intestine isn’t absorbing nutrients like it should.
  • Liver function: The disease can affect your liver and bile duct.

Computed tomography (CT) scan: CT scanning uses computer-aided X-ray techniques to make more detailed images of the abdomen and pelvis than can be seen in traditional X-rays. CT scans can help find abscesses that might not show up on other X-rays. Abscesses are small pockets of infection.

Leukocyte scintigraphy: White blood cells gather at spots in your body where there’s inflammation. For this test, the doctor will take a little blood from your arm and add a harmless amount of a radioactive substance. He’ll put it back in your body and use a special camera to see if the cells travel to spots in your gastrointestinal tract that could signal Crohn’s. It’s not a commonly used test.

Magnetic resonance imaging (MRI): Use of MRI to make a Crohn’s diagnosis is on the rise. This test gives your doctor a clear picture of the inside of your body, but it doesn’t subject you to radiation. It can help your doctor see your small intestines and spot an anal abscess (pus-filled sore) or fistula (tunnel that forms between an abscess and one of your anal glands). When you get this test, you’ll lie on a table that slides into a machine, so let your doctor know if you have a problem with enclosed spaces.
Video capsule endoscopy: For video capsule endoscopy, you swallow a small capsule or pill that holds a miniature video camera. As it travels through your small intestine, it sends images of the lining to a receiver you wear on a belt around your waist. The doctor downloads the images and reviews them on a computer. They can provide detailed information about early, mild problems associated with Crohn’s disease. This technique may be especially helpful if you have symptoms of Crohn’s disease that can’t be seen by other small bowel tests.
While video endoscopy can provide valuable information, it won’t work for everyone. You should avoid it if:
  • You have an obstruction in the small intestine. The capsule could get stuck and make the obstruction worse.
  • You have a narrowing in the small intestine, such as from Crohn’s disease, previous surgery, or previous radiation therapy. The capsule might become stuck.
  • You have an implanted device like a pacemaker or defibrillator for your heart. Some doctors worry that wireless transmissions from the capsule might interfere with them.

Crohn’s Disease Treatment

Crohn’s disease, also known as ileitis or regional enteritis, is a chronic illness. In Crohn’s, the intestine, bowel, or other part of the digestive tract becomes inflamed and ulcerated — marked with sores. Along with ulcerative colitis, Crohn’s disease is part of a group of diseases known as inflammatory bowel disease (IBD).
Crohn’s disease usually affects the lower part of the small intestine, which is called the ileum, and the beginning of the colon. The disease, though, can occur in any part of the gastrointestinal system. Thus, the disorder may affect the large or small intestine, the stomach, the esophagus, or even the mouth.



Your care team may recommend surgery if they think the benefits outweigh the risks or that medicines are unlikely to work.

Surgery can relieve your symptoms and help stop them coming back for a while, although they’ll usually return eventually.

The main operation used is called a resection. This involves:

  • Making small cuts in your tummy (keyhole surgery).
  • Removing a small inflamed section of bowel.
  • Stitching the healthy parts of bowel together.

It’s usually done under general anaesthetic (while you’re asleep). You may be in hospital for about a week and it might take a few months to fully recover. Sometimes you may need an ileostomy (where poo comes out into a bag attached to your tummy) for a few months to let your bowel recover before it’s stitched back together. You may need to take medicine after surgery to help prevent symptoms returning.



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