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Irritable bowel syndrome

Definition

Irritable bowel syndrome (IBS) refers to a disorder of the lower intestinal tract. It involves abdominal pain and abnormal bowel movements. Emotional stress often makes the symptoms worse.

It is not the same as inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis.

Alternative Names

Nervous indigestion; Spastic colon; Intestinal neurosis; Functional colitis; Irritable colon; Mucous colitis; Laxative colitis; IBS

Causes

IBS involves a combination of abdominal pain and constipation, diarrhea, or an alternating pattern of these problems.

There are many possible causes. For example, there may be a problem with muscle movement in the intestine or a lower tolerance for stretching and movement of the intestine. There is no problem with the structure of the intestine.

It is not clear why patients develop IBS, but in some instances, it occurs after an intestinal infection. This is called postinfectious IBS. There may also be other triggers.

IBS can occur at any age, but it often begins in adolescence or early adulthood. It is more common in women. The condition is the most common intestinal complaint for which patients are referred to a gastroenterologist.

Symptoms

Symptoms range from mild to severe. Most people have mild symptoms. IBS symptoms may be worse in patients who also have stress or mood disorders, such as anxiety and depression. However, it is important to understand that these conditions do not cause IBS.

Symptoms may include:

• Abdominal distention
• Abdominal fullness, gas, bloating
• Abdominal pain that:
  • Comes and goes
  • Is reduced or goes away after a bowel movement
  • Occurs after meals
• Chronic and frequent constipation, usually accompanied by pain
• Chronic and frequent diarrhea, usually accompanied by pain
• Emotional distress
• Depression
• Loss of appetite

Exams and Tests

Most of the time, your doctor can diagnose IBS with few or no tests. Tests usually reveal no problems. Some experts recommend a lactose-free diet for 2 weeks to evaluate for possible lactase deficiency.

Some patients may need an endoscopy, especially if symptoms begin later in life. Younger patients with persistent diarrhea may need this test to look for inflammatory bowel diseases that can cause similiar symptoms, such as Crohn's disease or ulcerative colitis. You may need additional tests if you have blood in your stool, weight loss, signs of anemia, or you have recently traveled.

Patients over age 50 should be screened for colon cancer.

Treatment

The goal of treatment is to relieve symptoms.

Lifestyle changes can be helpful in some cases of IBS. For example, regular exercise and improved sleep habits may reduce anxiety and help relieve bowel symptoms.

Dietary changes can be helpful. However, no specific diet can be recommended for IBS in general, because the condition differs from one person to another. Increasing dietary fiber and avoiding foods and drinks that stimulate the intestines (such as caffeine) may help.

Other possible treatments may include:

• Counseling in cases of severe anxiety or depression
• Antidiarrheal medications for those whose main symptom is diarrhea
• Low-dose antidepressants to help relieve intestinal pain
• Medications to stimulate bowel movements for those with constipation

Outlook (Prognosis)

Irritable bowel syndrome may be a lifelong condition, but symptoms can often be improved or relieved through treatment.

When to Contact a Medical Professional

Call your health care provider if you have symptoms of irritable bowel syndrome or if you notice a persistent change in your bowel habits.

References

Talley NJ. Functional gastrointestinal disorders: irritable bowel syndrome, dyspepsia, and noncardiac chest pain. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 139.

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