Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional bowel disorder characterized by altered bowel habits associated with chronic abdominal bloating or pain. IBS is different from IBD (Inflammatory bowel disease). About 1 in 6 people in the U.S. have some symptoms of IBS. Females are more likely to have IBS than males. Based on the bowel habits, IBS can be classified as: 1. Diarrhea-predominant (IBS-D); 2. Constipation-predominant (IBS-C); 3. IBS with mixed diarrhea and constipation(IBS-M); 4. IBS with alternating diarrhea and constipation(IBS-A). IBS is used to be a diagnosis of exclusion, which means patients with IBS have alternated bowel habits and pain, but no organic pathology can be found. Now, most experts think IBS is a GI disorder related to post bacterial infection, psychological, neurophysiological alterations, etc.

Causes and Risk Factors:

Common ones are:

  • Younger age
  • Female gender
  • Family history of IBS
  • Certain bacterial infection
  • Anxiety or depression
  • Stress

Symptoms and Signs

Common ones are:

  • Altered bowel habits
  • Diarrhea. Diarrhea mostly occurs at daytime, rarely at night.
  • Constipation
  • Diarrhea alternates with constipation
  • Abdominal pain. Pain is characteristically relieved after a bowel movement.
  • Bloating
  • Mucus in stool

Symptoms that are not support of IBS:

  • Rectal bleeding
  • Fatty diarrhea
  • Fever
  • Weight loss
  • Diarrhea happens at night
  • Old person
  • Happen suddenly

Diagnosis and Treatment

Diagnosis is based on a history and physical examination. The Rome III criteria for the diagnosis of IBS require that patients have had recurrent abdominal pain or discomfort at least 3 days per month during the previous 3 months that is associated with 2 or more of the following:

  • Relieved by defecation
  • Onset associated with a change in stool frequency
  • Onset associated with a change in stool form or appearance

Meanwhile, one or more of the following tests are necessary to rule out other illnesses that are similar to IBS:

After the diagnosis is confirmed, treatment is focused on the relief of symptoms, assurance, psychological counseling and cognitive behavior therapy, etc.


  1. PubMed Health.
  2. Wikipedia.
  3. Mayo clinic online health information.
  4. Sleisenger and Fordtran's Gastrointestinal and Liver Disease- by Mark Feldman MD, et al.
  5. The Little Black Book of Gastroenterology-by David W. Hay.
  6. Principles of Clinical Gastroenterology by Tadataka Yamada, et al.