What Is Crohn’s Disease

Crohn’s disease is an intestinal inflammation affecting the wall of the intestines and other parts of the gastrointestinal tract. It is also called regional enteritis, ileocloitis or granulomatus ileitis.

  • Chronic or recurring diarrhea accompanied by abdominal cramps and pain are the usual symptoms. Fever, bloody stools and significant weight loss due to loss of appetite and malabsorption are also common.
  • The reason for developing Crohn’s disease is not known but abnormalities of the immune system and a genetic predisposition are thought to be responsible for this condition.
  • Barium x-rays and a viewing test called colonoscopy help diagnose the condition.
  • The treatment focuses on controlling intestinal inflammation and reducing symptoms as Crohn’s disease cannot be cured.
  • In some cases, surgical intervention may be necessary.

The exact reason for Crohn’s disease is still not clear though it is believed to be caused by the overreaction of the immune system to various stimuli such as infections, food and environmental factors. A genetic factor also is involved. Smoking is found to be an environmental factor which increases the risk of developing Crohn’s disease as well as worsening it.

Crohn’s disease is becoming increasingly common all over the world but it is more prevalent in the developed countries situated in the northern part of the world. Both men and women are equally affected, and a strong family history is often encountered. People of Jewish descent, especially having Ashkenazim origin are predisposed to Crohn’s disease, the majority of them developing it by the time they are 35 years old. Some may develop it much earlier, at 15 to 25 years of age.

Crohn’s disease usually develops in the large intestine and the latter part of the small intestine called ileum. But its occurrence is not limited to the intestines; it can affect any location along the digestive tract, including the mouth and the anus. The perianal skin also can be affected. The disease affects different people in different ways. In 35% of those affected, the disease is restricted to the small intestine, while 20% have it in the large intestine only.  In 45% of those with this condition may have it in both the intestines. Along the length of the affected areas there may be healthy portions called skip areas. But during an active flare up, the entire length and thickness of the intestines may be affected.


The earliest symptoms of this condition are usually chronic diarrhea and fever accompanied by abdominal cramping and pain. Loss of appetite is another symptom. Significant weight loss also may develop. Once the symptoms appear, they usually continue for several days and even weeks, and then subside without any specific treatment. But the recovery is temporary and the disease generally continues throughout life with intermittent active and passive phases. The flare ups may be severe or mild; it may last for a short period or may be prolonged. During severe episodes, pain may be intense and loss of blood and fluids through diarrhea may make a person severely dehydrated and weak. The flare ups usually occur in the same area but may spread to the areas nearby, especially when the affected portion is surgically removed. The reason for the unpredictable and irregular flare ups as well as the severity of the episodes is unknown, making the management of the disease difficult.

When Crohn’s disease develops in children, the usual symptoms are not similar to those of the adult onset of the disease. Fever and inflammation of the joints are the first symptoms in children. Slower rate of growth and fatigue due to anemia are common while typical symptoms like diarrhea and abdominal cramps may be completely absent.

Complications: Obstruction of the intestines, caused by the scar tissue which may have formed there due to this disease, is a major complication of Crohn’s disease. Ulcers may grow deep into the wall of the intestines forming abscesses filled with pus. Abnormal channels called fistulas may develop between the intestines and surrounding organs such as the urinary bladder. Sometimes fistulas from the large intestine grow towards the surface of the skin and develop openings around the anus, leaking fecal matter. Fistulas may originate from the small intestine also, but large perforations are uncommon.

Bleeding from the rectum is a common occurrence when Crohn’s disease affects the large intestine. Prolonged intestinal inflammation due to Crohn’s disease increases the risk of developing colon cancer. One third of people who have Crohn’s disease of the large intestine usually develop disorders such as fissures and fistulas in the anus or in the surrounding area. Other complications due to this condition include infections of the urinary tract and malabsorption syndromes. People with this condition have a higher risk of developing gallstones and kidney stones, as well as a condition called amyloidosis, characterized by the deposits of an abnormal substance called amyloid protein in various organs of the body.

During flare ups of Crohn’s disease, apart from the symptoms related to the digestive system, various other abnormal conditions also appear, such as:

  • aphthous stomatitis or painful sores in the mouth,
  • arthritis, characterized by inflammation, pain, and stiffness of the joints,
  • erythema nodosum or inflamed nodules developing on the hands and legs,
  • episcleritis, which is the inflammation of the sclera or the white part of the eye ball, and,
  • pyoderma gangrenosum, in which pus-filled, blue-red sores develop on the skin.

Certain other inflammatory conditions are usually present in people who have Crohn’s disease even when it is in remission. Some of them are; uveitis, or eye inflammation, sacroiliitis, or pelvic joint inflammation, sclerosing cholangitis, which is an inflammation affecting the bile ducts, and ankylosing spondylitis, or the inflammation occurring in the spine.


Crohn’s disease is suspected when a person has several episodes of diarrhea accompanied by abdominal cramps and pain. The medical history of the patient also helps in diagnosis, as a person with this condition usually has disorders associated with the anus such as fistulas and anal fissures. If there are family members diagnosed with Crohn’s disease, there is a high probability as well. Inflammation of eyes, joints and skin are other symptoms which indicate this disease. During physical examination, a lump may be detected on the right side of the lower abdomen.

There are no specific lab tests to detect Crohn’s disease, but abnormal conditions such as high white blood cell count, anemia, and lower blood levels of albumin, when detected in a blood test, may be indicative of this condition. C-reactive protein level in the blood may be high too, which is a sign of intestinal  inflammation.

The large intestine is examined through a flexible viewing tube called colonoscope and a tissue sample is collected for detailed examination under the microscope. Colonoscopic examination may not detect Crohn’s disease in the small intestine. Since the most probable location of Crohn’s disease affecting the small intestine is its last portion, which is nearest to the large intestine, the colonoscope is further extended to view the small intestine too. Barium swallow x-ray is usually done to detect Crohn’s disease in the small intestine. Barium enema followed by an x-ray can often detect Crohn’s disease in the large intestine too.

CT scan is the ideal test for inflammatory bowel diseases as it can help differentiate between ulcerative colitis and Crohn’s disease. It can also detect abnormalities such as fistulas and abscesses on the outer wall of the intestine which may be causing the inflammation. Capsule endoscopy, in which a capsule fitted with a tiny camera is swallowed, may help get a clear view of the entire length of the intestinal tract.

Prognosis and Treatment

Crohn’s disease has no direct bearing on the life span of those having this condition. But since people who have Crohn’s disease for prolonged periods have a higher risk of developing intestinal cancers, it may indirectly affect longevity.

There are no treatments to cure Crohn’s disease; hence the focus of the treatment is on managing the disease by reducing the inflammation and alleviating the symptoms. Various drug therapies and surgery are the options available for treating this disease.

Antidiarrheal Drugs: They help in reducing diarrhea and abdominal cramps. They include anticholinergic drugs which block neurotransmitters, such as loperamide and diphenoxylate as well as codeine and deodorized tincture of opium. These drugs are to be taken orally before taking meals. Soluble dietary fibers such as Psyllium husk and methylcellulose help in adding bulk and firmness to stools, thereby reducing irritation to the anus.

Anti-Inflammatory Drugs: Drug sulfasalazine, and other drugs like balsalazide, olsalazine, and mesalamine, related to it, help in reducing the inflammation of the digestive tract, especially when the disease is mild and is mainly affecting the large intestine. Recurrence of the disease has been found to be lowered with the use of mesalamine. However, when the flare ups are severe, these drugs are not very effective.

In spite of the side effects of corticosteroids, especially with their long term use, they are widely and effectively used in the management of Crohn’s disease. The corticosteroid predinisone may be taken orally to reduce symptoms such as diarrhea, fever and abdominal cramping and pain. It may even increase the appetite and help in weight gain. To avoid long term use, the drug is given in high doses at the start of the therapy and then, as the symptoms of intestinal inflammation decrease, the dosage is also reduced, and then gradually tapered off. Side effects are much less with another corticosteroid drug budesonide, but it is not as effective as prednisone and relapses may occur within the next 6 to 9 months.

During very severe flare ups, patients may have to be admitted in the hospital for intravenous corticosteroid therapy, as well as for rehydration and nutritional support given intravenously. Oral feeding is stopped initially till the inflammation is under control. If blood loss through bleeding from the rectum is high, blood transfusion may be given. Anemia is treated by giving iron and folic acid supplements.

Immunomodulating Drugs: Certain drugs like mercaptopurine and azathioprine, which reduce the immune response of the body, are found to be effective in treating Crohn’s disease. They prolong the remission period, and help relieve the symptoms of people who have not benefitted from other drug therapies. Though they can heal fistulas and also help in reducing corticosteroid use, it may take one to three months to derive tangible benefits from their action. Another concern is their potential for causing side effects of a serious nature, such as lowering of white blood cells and pancreatitis. Patients put on immunomodulating drugs have to be closely monitored for the development of low WBC count, pancreatitis and allergic reactions. Blood tests to detect the levels of the metabolites of mercaptopurine and azathioprine may help in adjusting the dosage suitably. Genetic testing also may be done to assess the suitability and dosage of these drugs in different people as the there may be variations in the enzyme which metabolizes these drugs.

Methotrexate is a drug which is given once every week, orally, or by an injection, to people unable to tolerate both immunomodulating drugs and corticosteroids. High doses of Cyclosporine may heal fistulas but it is not safe for long-term use.

A comparatively new drug called infliximab, obtained from monoclonal antibodies, may be administered intravenously to people with severe or moderate forms of the disease. It is an immune modifier which may help some people who are not responding adequately to other medications. It also helps in treating fistulas and in controlling the severity of the disease. However, its action is short-term, and being a new drug, all of its side effects are still not known. When the immunity is lowered due to the use of this drug, it may result in the worsening of infections already existing in the body, including tuberculosis. The risk of developing certain cancers is also elevated. Reactions to the drug may develop in some people in the form of rashes and fever when the drug is being administered. Another related drug called Adalimumab may help those who are unable to tolerate infliximab or have become resistant to it. This drug is also an immuomodifier.

 Broad-Spectrum Antibiotics: Antibiotic drugs, which work against a wide variety of bacteria which cause infections in the digestive tract, are used in treating Crohn’s disease. The antibiotic drug Metronidazole helps in treating anal abscesses and fistulas. In addition to clearing up infections which may be causing the inflammation, Metronidazole also reduces other symptoms like abdominal pain and diarrhea typical of Crohn’s disease. But long-term use of the drug may result in nerve damage, which may be recognizable by the pins and needles sensation in the hands and legs. This side effect is reversible with the discontinuation of the drug, but the benefits are also lost on stopping the medication. Several other antibiotics such as levofloxacin or ciprofloxacin are often used instead of metronidazole, or along with it. Occasionally, an antibiotic named Rifaximin, which is nonabsorbable, is also used to treat Crohn’s disease.

Dietary Regimens: A liquid diet, consisting of all the nutritional substances in the right proportion according to the requirements of the body, is found to help people with Crohn’s disease when fistulas and obstructions in the intestines are present. When tube feeding of the liquid formula is administered to children at bedtime, it improves their nutritional status, resulting in better growth. These liquid diets may be given besides surgery or to help postpone the surgery. In some cases, when Crohn’s disease has resulted in severe malabsorption and nutritional deficiencies, intravenous administration of nutrient solutions may be necessary.

Surgery: It may become necessary at some stage or other in almost all the people suffering from Crohn’s disease. When the drug therapy to heal the fistulas and abscesses in the gastrointestinal tract does not work, surgery may be the only option. Obstructions in the intestines, caused due to scar tissue formation resulting from Crohn’s disease, often necessitate surgical removal of the affected area. Even though the removal of diseased portions may alleviate symptoms, it is not a permanent cure, as the disease may affect new areas, especially those adjacent to the removed area. Though drugs administered following the surgery may help in reducing recurrence, half of those who have undergone a surgery usually require another one. Due to this reason, surgery is considered as a last resort, when all possible drug therapies prove to be ineffective. However, people who have had surgical removal of the diseased portions of their intestines often experience a dramatic improvement in their condition.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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