Irritable Bowel Syndrome

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Basics

Description

  • A gastrointestinal disorder characterized by
    • Chronic and/or recurrent abdominal pain or discomfort, bloating and distension, and alteration in bowel habits in the absence of an organic cause.
  • May be characterized as diarrhea-predominant or constipation-predominant; may alternate between symptoms
  • Synonym(s): spastic colon; irritable colon

Epidemiology

Irritable bowel syndrome (IBS) accounts for 30–50% of visits to gastroenterologists:

  • Second only to upper respiratory infection as cause of lost workdays
Prevalence

Pooled estimate of 11% IBS prevalence internationally; ranges from South Asia (7%) to South America (21%); prevalence in North America is 12%.

  • Predominant age: 20 to 39 years
  • If age >50 years, consider other diagnoses.
  • In the United States, female > male (2:1)
  • More common in low socioeconomic communities

Etiology and Pathophysiology

  • The etiology is unknown; associated with abnormalities of intestinal motility and enhanced sensitivity to visceral stimuli
  • The trigger may be luminal or environmental.
  • Evidence for the role of small intestinal bacterial overgrowth (SIBO) in IBS and association with antibiotic therapy is controversial; older age and female gender are predictors of SIBO in IBS patients.
  • The role of food sensitivity, genetic, and psychosocial causes are also under active investigation.
  • Four bowel patterns in the Rome IV classification:
  • IBS-D (diarrhea predominant); IBS-C (constipation predominant); IBS-M (mixed diarrhea and constipation; IBS-U (unclassified-symptoms cannot be categorized into one of the three subtypes)
  • The utility of subtyping has been questioned. Many patients change categories/subtypes over time.

Genetics
Unknown. IBS tracks in some families. Twin studies do not, however, show a clear genetic component.

Risk Factors

  • Other family members with similar gastrointestinal (GI) disorder
  • History of childhood sexual abuse
  • Sexual/domestic abuse (primarily in women)
  • Depression
  • Gastrointestinal infection

Pediatric Considerations
No risk to mother or fetus

General Prevention

See “Diet.”

Commonly Associated Conditions

  • Chronic migraine
  • Fibromyalgia
  • Chronic fatigue syndrome
  • Sleep disorders
  • Psychiatric disorders: major depression, anxiety, somatoform disorders, and posttraumatic stress
  • Chronic pelvic pain
  • Temporomandibular joint dysfunction

-- To view the remaining sections of this topic, please or --

Basics

Description

  • A gastrointestinal disorder characterized by
    • Chronic and/or recurrent abdominal pain or discomfort, bloating and distension, and alteration in bowel habits in the absence of an organic cause.
  • May be characterized as diarrhea-predominant or constipation-predominant; may alternate between symptoms
  • Synonym(s): spastic colon; irritable colon

Epidemiology

Irritable bowel syndrome (IBS) accounts for 30–50% of visits to gastroenterologists:

  • Second only to upper respiratory infection as cause of lost workdays
Prevalence

Pooled estimate of 11% IBS prevalence internationally; ranges from South Asia (7%) to South America (21%); prevalence in North America is 12%.

  • Predominant age: 20 to 39 years
  • If age >50 years, consider other diagnoses.
  • In the United States, female > male (2:1)
  • More common in low socioeconomic communities

Etiology and Pathophysiology

  • The etiology is unknown; associated with abnormalities of intestinal motility and enhanced sensitivity to visceral stimuli
  • The trigger may be luminal or environmental.
  • Evidence for the role of small intestinal bacterial overgrowth (SIBO) in IBS and association with antibiotic therapy is controversial; older age and female gender are predictors of SIBO in IBS patients.
  • The role of food sensitivity, genetic, and psychosocial causes are also under active investigation.
  • Four bowel patterns in the Rome IV classification:
  • IBS-D (diarrhea predominant); IBS-C (constipation predominant); IBS-M (mixed diarrhea and constipation; IBS-U (unclassified-symptoms cannot be categorized into one of the three subtypes)
  • The utility of subtyping has been questioned. Many patients change categories/subtypes over time.

Genetics
Unknown. IBS tracks in some families. Twin studies do not, however, show a clear genetic component.

Risk Factors

  • Other family members with similar gastrointestinal (GI) disorder
  • History of childhood sexual abuse
  • Sexual/domestic abuse (primarily in women)
  • Depression
  • Gastrointestinal infection

Pediatric Considerations
No risk to mother or fetus

General Prevention

See “Diet.”

Commonly Associated Conditions

  • Chronic migraine
  • Fibromyalgia
  • Chronic fatigue syndrome
  • Sleep disorders
  • Psychiatric disorders: major depression, anxiety, somatoform disorders, and posttraumatic stress
  • Chronic pelvic pain
  • Temporomandibular joint dysfunction

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